in accordance with the present invention , there are provided methods of modulating the activity of acetylcholine receptors . as employed herein , the phrase “ modulating the activity of acetylcholine receptors ” refers to a variety of therapeutic applications , such as the treatment of alzheimer &# 39 ; s disease and other disorders involving memory loss and / or dementia ( including aids dementia ); cognitive dysfunction ( including disorders of attention , focus and concentration ), disorders of extrapyramidal motor function such as parkinson &# 39 ; s disease , progressive supramuscular palsy , huntington &# 39 ; s disease , gilles de la tourette syndrome and tardive dyskinesia ; mood and emotional disorders such as depression , panic , anxiety and psychosis ; substance abuse including withdrawal syndromes and substitution therapy ; neuroendocrine disorders and dysregulation of food intake , including bulemia and anorexia ; disorders of nociception and control of pain ; neuroprotection ; autonomic disorders including dysfunction of gastrointestinal motility and function such as inflammatory bowel disease , irritable bowel syndrome , diarrhea , constipation , gastric acid secretion and ulcers ; pheochromocytoma ; cardiovascular dysfunction including hypertension and cardiac arrhythmias , comedication in surgical procedures , and the like . the compounds of the present invention are especially useful for the treatment of alzheimer &# 39 ; s disease as well as other types of dementia ( including dementia associated with aids ), parkinson &# 39 ; s disease , cognitive dysfunction ( including disorders of attention , focus and concentration ), attention deficit syndrome , affective disorders , and for the control of pain . thus modulation of the activity of acetylcholine receptors present on or within the cells of a patient suffering from any of the above - described indications will impart a therapeutic effect . invention methods comprise contacting cell - associated acetylcholine receptors with a concentration of a compound of formula z sufficient to modulate the activity of said acetylcholine receptors , compounds having formula z being defined as follows : or enantiomers , diastereomeric isomers or mixtures of any two or more thereof , or pharmaceutically acceptable salts thereof , a and b are independently selected from — n — or — c —, with the proviso that one of a and b is — n —; each of r 1 , r 2 , r 3 , r 4 and r 5 are independently selected from hydrogen , halogen , cyano , cyanomethyl , nitro , alkyl , substituted alkyl , cycloalkyl , substituted cycloalkyl , alkenyl , substituted alkenyl , alkynyl , substituted alkynyl , aryl , substituted aryl , alkylaryl , substituted alkylaryl , arylalkyl , substituted arylalkyl , heterocyclic , substituted heterocyclic , trifluoromethyl , pentafluoroethyl , — or a , — o — c ( o )— r a , — o — c ( o )— n ( r a ) 2 , — sr a , — nhc ( o ) r a or — nhso 2 r a , wherein r a is selected from h , lower alkyl , substituted lower alkyl , aryl or substituted aryl , or — nr b r b , wherein each r b is independently selected from hydrogen or lower alkyl , such that when a is — n —, r 1 is absent and when b is — n —, r 3 is absent ; d is optionally present ; and when d is present , d is selected from lower alkylene , substituted lower alkylene , cycloalkylene , substituted cycloalkylene , lower alkenylene , substituted lower alkenylene , or lower alkynylene ; e is optionally present ; and when e is present , e is selected from — o —, — c ( o )—, — c ( o )— nr c —, — c ( o )— o —, — o — c ( o )— nr c —, — s —, — s ( o )—, — s ( o )— nr c —, — s ( o ) 2 —, — s ( o ) 2 — nr c — or — s ( o )═ nh , wherein r c is selected from hydrogen , lower alkyl or substituted lower alkyl ; g is optionally present ; and when g is present , g is selected from lower alkylene , substituted lower alkylene , lower alkenylene , substituted lower alkenylene or lower alkynylene ; r e and r f are independently selected from hydrogen , lower alkyl , lower alkenyl , lower alkynyl , lower cycloalkyl and cycloalkyl , or r e and r f combine to form a 3 - 7 membered ring ( with 4 - 6 membered rings being presently preferred ), or one or both r * can cooperate with one another or with r d to form further ring ( s ) or when r * does not cooperate to form a ring , r * is hydrogen , x is optionally present , and when present is selected from — o —, — ch 2 o —, — s —, — ch 2 s —, — s ( o )—, — ch 2 s ( o )—, — s ( o ) 2 —, — ch 2 s ( o ) 2 — or — ch 2 n —, and r d is selected from hydrogen , lower alkyl or lower cycloalkyl , or r d is absent when the nitrogen atom to which it is attached participates in the formation of a double bond , with the proviso that when a is — n —, b is — c —, one of r 2 , r 3 or r 5 is cl , d is absent , e is — s — or — o —, and g is alkylene containing 2 - 4 carbon atoms and j is j ′; or when a is — n —, b is — c —, d is absent , g is absent or alkylene containing 1 - 4 carbon atoms , and j is j ″, and j ″ is monocyclic , tropanyl or quinuclidyl , then said modulation does not embrace the control of pain . bicyclic derivatives of the above - described nitrogen - containing cyclic moieties include a wide variety of azabicyclic moieties , as described in greater detail herein below . as employed herein , the phrase “ an effective amount ”, when used in reference to compounds of the invention , refers to doses of compound sufficient to provide circulating concentrations high enough to impart a beneficial effect on the recipient thereof . such levels typically fall in the range of about 0 . 001 up to 100 mg / kg / day ; with levels in the range of about 0 . 05 up to 10 mg / kg / day being preferred . as employed herein , “ lower alkyl ” refers to straight or branched chain alkyl radicals having in the range of about 1 up to 4 carbon atoms ; “ alkyl ” refers to straight or branched chain alkyl radicals having in the range of about 1 up to 12 carbon atoms ; “ substituted alkyl ” refers to alkyl radicals further bearing one or more substituents such as hydroxy , alkoxy ( of a lower alkyl group ), mercapto ( of a lower alkyl group ), aryl , heterocyclic , halogen , trifluoromethyl , pentafluoroethyl , cyano , cyanomethyl , nitro , amino , carboxyl , carbamate , sulfonyl , sulfonamide , and the like ; “ lower alkylene ” refers to straight or branched chain alkylene radicals ( i . e ., divalent alkyl moieties , e . g ., methylene ) having in the range of about 1 up to 4 carbon atoms ; “ alkylene ” refers to straight or branched chain alkylene radicals having in the range of about 1 up to 12 carbon atoms ; and “ substituted alkylene ” refers to alkylene radicals further bearing one or more substituents as set forth above ; “ lower cycloalkyl ” refers to cyclic radicals containing 3 or 4 carbon atoms , “ substituted lower cycloalkyl ” refers to lower cycloalkyl radicals further bearing one or more substituents as set forth above , “ cycloalkyl ” refers to cyclic ring - containing radicals containing in the range of about 3 up to 8 carbon atoms , and “ substituted cycloalkyl ” refers to cycloalkyl radicals further bearing one or more substituents as set forth above ; “ cycloalkylene ” refers to cyclic ring - containing divalent radicals containing in the range of about 3 up to 8 carbon atoms ( e . g . cyclohexylene ), and “ substituted cycloalkylene ” refers to cycloalkylene radicals further bearing one or more substituents as set forth above ; “ lower alkenyl ” refers to straight or branched chain hydrocarbyl radicals having at least one carbon - carbon double bond , and having in the range of about 2 up to 4 carbon atoms , and “ substituted lower alkenyl ” refers to alkenyl radicals further bearing one or more substituents as set forth above ; “ alkenyl ” refers to straight or branched chain hydrocarbyl radicals having at least one carbon - carbon double bond , and having in the range of about 2 up to 12 carbon atoms ( with radicals having in the range of about 2 to 6 carbon atoms presently preferred ), and “ substituted lower alkenyl ” refers to alkenyl radicals further bearing one or more substituents as set forth above ; “ lower alkenylene ” refers to straight or branched chain alkenylene radicals ( i . e ., divalent alkenyl moieties , e . g ., ethylidene ) having at least one carbon - carbon double bond , and having in the range of about 2 up to 4 carbon atoms , and “ substituted lower alkenylene ” refers to divalent alkenyl radicals further bearing one or more substituents as set forth above ; “ alkenylene ” refers to straight or branched chain divalent alkenyl moieties having at least one carbon - carbon double bond , and having in the range of about 2 up to 12 carbon atoms ( with divalent alkenyl moieties having in the range of about 2 to 6 carbon atoms presently preferred ), and “ substituted lower alkenylene ” refers to divalent alkenyl radicals further bearing one or more substituents as set forth above ; “ lower alkynyl ” refers to straight or branched chain hydrocarbyl radicals having at least one carbon - carbon triple bond , and having in the range of about 2 up to 4 carbon atoms , and “ substituted lower alkynyl ” refers to alkynyl radicals further bearing one or more substituents as set forth above ; “ alkynyl ” refers to straight or branched chain hydrocarbyl radicals having at least one carbon - carbon triple bond , and having in the range of about 2 up to 12 carbon atoms ( with radicals having in the range of about 2 up to 6 carbon atoms presently being preferred ), and “ substituted alkynyl ” refers to alkynyl radicals further bearing one or more substituents as set forth above ; “ lower alkynylene ” refers to straight or branched chain alkynylene radicals ( i . e ., divalent alkynyl moieties , e . g ., ethynylidene ) having at least one carbon - carbon triple bond , and having in the range of about 2 up to 4 carbon atoms , and “ substituted lower alkynylene ” refers to divalent alkynyl radicals further bearing one or more substituents as set forth above ; “ alkynylene ” refers to straight or branched chain divalent alkynyl moieties having at least one carbon - carbon triple bond , and having in the range of about 2 up to 12 carbon atoms ( with divalent alkynyl moieties having in the range of about 2 to 6 carbon atoms presently being preferred ), and “ substituted alkynylene ” refers to divalent alkynyl radicals further bearing one or more substituents as set forth above ; “ aryl ” refers to aromatic radicals having in the range of 6 up to 14 carbon atoms and “ substituted aryl ” refers to aryl radicals further bearing one or more substituents as set forth above ; “ alkylaryl ” refers to alkyl - substituted aryl radicals and “ substituted alkylaryl ” refers to alkylaryl radicals further bearing one or more substituents as set forth above ; “ arylalkyl ” refers to aryl - substituted alkyl radicals and “ substituted arylalkyl ” refers to arylalkyl radicals further bearing one or more substituents as set forth above ; “ arylalkenyl ” refers to aryl - substituted alkenyl radicals and “ substituted arylalkenyl ” refers to arylalkynyl radicals further bearing one or more substituents as set forth above ; “ arylalkynyl ” refers to aryl - substituted alkynyl radicals and “ substituted arylalkynyl ” refers to arylalkynyl radicals further bearing one or more substituents as set forth above ; “ heterocyclic ” refers to cyclic ( i . e ., ring - containing ) radicals containing one or more heteroatoms ( e . g ., n , o , s ) as part of the ring structure , and having in the range of 3 up to 14 carbon atoms and “ substituted heterocyclic ” refers to heterocyclic radicals further bearing one or more substituents as set forth above ; “ azabicyclic moieties ” refers to fully saturated bicyclic species bearing a nitrogen atom at one of the ring positions , or such moieties may contain one or more sites of unsaturation . examples of azabicyclic moieties contemplated for use in the practice of the present invention include azabicycloalkanes such as 7 - azabicyclo [ 2 . 2 . 1 ] heptane , n - methyl 7 - azabicyclo [ 2 . 2 . 1 ] heptane , 8 - azabicyclo [ 3 . 2 . 1 ] octane , n - methyl 8 - azabicyclo [ 3 . 2 . 1 ] octane , 1 - azabicyclo [ 2 . 2 . 2 ] octane , n - methyl 1 - azabicyclo [ 2 . 2 . 2 ] octane , 9 - azabicyclo [ 4 . 2 . 1 ] nonane , n - methyl 9 - azabicyclo [ 4 . 2 . 1 ]- nonane , and the like ; azabicycloalkenes such as 9 - methyl - 9 - azabicyclo [ 4 . 2 . 1 ] non - 2 - ene , and the like . the stereochemistry of azabicyclic moieties includes both endo - and exo - isomers ; in accordance with the present invention there are also provided compounds of formula z as defined hereinabove , excluding compounds wherein : a is — n —, b is — c —, one of r 2 , r 3 or r 5 is cl , d is absent , e is — s — or — o —, g is alkylene containing 2 - 4 carbon atoms and j is j ′, or a is — n —, b is — c —, d is absent , g is absent or alkylene containing 1 - 4 carbon atoms , j is j ″, and j ″ is monocyclic , tropanyl or quinuclidyl . in accordance with the present invention , a and b are independently selected from — n — and — c — with the proviso that one of a and b is — n —. each of r 1 through r 5 are independently selected from hydrogen , halogen , cyano , cyanomethyl , nitro , alkyl , substituted alkyl , cycloalkyl , substituted cycloalkyl , alkenyl , substituted alkenyl , alkynyl , substituted alkynyl , aryl , substituted aryl , alkylaryl , substituted alkylaryl , arylalkyl , substituted arylalkyl , heterocyclic , substituted heterocyclic , perfluoro alkyl ( such as , for example , trifluoromethyl , pentafluoroethyl , and the like ), — or a , — o — c ( o )— r a , — o — c ( o )— n ( r a ) 2 , — sr a , — nhc ( o ) r a or — nhso 2 r a , wherein r a is selected from h , lower alkyl , substituted lower alkyl , aryl or substituted aryl , or — nr b r b , wherein each r b is independently selected from hydrogen and lower alkyl . preferred compounds are those in which r 1 through r 5 are each selected from hydrogen , halogen , alkyl , substituted e alkyl ( including perfluoroalkyl ), alkynyl , substituted alkynyl , — or a or — sr a , wherein r a is selected from h , lower alkyl or aryl , or — nr b r b , wherein each r b is independently selected from hydrogen or lower alkyl . more preferably each of r 1 through r 5 are independently selected from hydrogen , lower alkyl , halogen , hydroxyl , hydroxymethyl , alkoxy , amino , and the like . in accordance with the present invention , d , when present , is selected from straight chain lower alkylene and substituted lower alkylene moieties , or cycloalkylene and substituted cycloalkylene , or lower alkenylene and substituted alkenylene moieties , or lower alkynylene moieties . it is presently preferred that d not be present , or when present , it is preferred that for d be a lower alkylene chain containing 1 to 3 carbon atoms in the backbone thereof . in particularly preferred compounds of the present invention d is absent or methylene . further in accordance with the present invention , e is selected from — o —, — c ( o )—, — c ( o ) o —, — s —, — s ( o )—, — s ( o ) 2 — or — c ( o ) nr c —, wherein r c is selected from hydrogen , lower alkyl or substituted lower alkyl . preferably e is selected from — o —, — s —, — c ( o ) o — or — s ( o ) 2 —. it is presently especially preferred that e is selected from — s — or — o —. still further in accordance with the present invention , g is selected from straight chain lower alkylene and substituted lower alkylene moieties ( preferably having up to 3 atoms in the backbone thereof ), or lower alkenylene moieties ( preferably having about 3 atoms in the backbone thereof ), or substituted lower alkenylene moieties and lower alkynylene moieties ( preferably having about 3 atoms in the backbone thereof ). presently preferred moieties for g are lower alkylene , of 1 to 3 carbon atoms . yet still further in accordance with the present invention , j is a dialkylamino group having the structure ( j ′): r e and r f are independently selected from hydrogen , lower alkyl , lower alkenyl , lower alkynyl , lower cycloalkyl and cycloalkyl , or r e and r f combine to form a 3 - 7 membered ring ( with 4 - 6 membered rings being presently preferred ), or one or both r * can cooperate with one another or with r d to form further ring ( s ), x is optionally present , and when present is selected from — o —, — ch 2 o —, — s —, — ch 2 s —, — s ( o )—, — ch 2 s ( o )—, — s ( o ) 2 —, — ch 2 s ( o ) 2 — or — ch 2 n —, and r d is selected from hydrogen , lower alkyl or lower cycloalkyl , or r d is absent when the nitrogen atom to which it is attached participates in the formation of a double bond . thus , for example , j can be a dialkylamino moiety , an aziridino moiety , azetidino moiety , tetrahydrooxazolo moiety , tetrahydrothiazolo moiety , pyrrolidino moiety , piperidino moiety , morpholino moiety , thiomorpholino moiety , piperazino moiety , an azabicyclic moiety , and the like . presently preferred compounds include those wherein j is an azetidino moiety , pyrrolidino moiety , 1 - methylpyrrolidino moiety , piperidine moiety ; 1 - methylpiperidine moiety , an azabicyclic moiety ( e . g ., 7 - azabicyclo [ 2 . 2 . 1 ] heptane , 8 - azabicyclo [ 3 . 2 . 1 ] octane , 1 - azabicyclo [ 2 . 2 . 2 ] octane , 9 - azabicyclo [ 4 . 2 . 1 ] nonane , 9 - methyl - 9 - azabicyclo [ 4 . 2 . 1 ] non - 2 - ene ), and the like . preferred compounds of the present invention include those wherein a and b are independently selected from — n — and — c — with the proviso that one of a and b is — n —, d is lower alkylene or absent ; e is as previously defined ; g is lower alkylene or lower alkenylene , and j forms a 4 -, 5 - or 6 - membered heterocyclic ring or is an azabiocyclic moiety . particularly preferred compounds of the present invention include those wherein a and b are as defined above , d is methylene or absent , e is — s — or — o —; g is methylene or ethylene ; and j is pyrrolidino , 1 - methylpyrrolidino , piperidino , 1 - methylpiperidino or an azabicyclic moiety . additional preferred compounds of the present invention include those wherein e is — c ( o ) o —; d is lower alkylene ; g is lower alkylene ; and j is pyrrolidino , 1 - methylpyrrolidino , piperidino , 1 - methylpiperidino or an azabicyclic moiety . additional preferred compounds of the invention include those wherein e is — s —; d is not present ; g is methylene or ethylene ; j is pyrrolidino , 1 - methylpyrrolidino , piperidino , 1 - methylpiperidino or an azabicyclic moiety . additional preferred compounds of the invention include those wherein e is — o —; d is methylene or not present ; g is methylene ; j is pyrrolidino , 1 - methylpyrrolidino , piperidino , 1 - methylpiperidino or an azabicyclic moiety . additional preferred compounds of the invention include those wherein e is — s —; d is methylene or not present ; g is methylene ; and at least one of r 1 , r 2 , r 3 , r 4 or r 5 is not hydrogen . additional preferred compounds of the invention include those wherein e is — s —; neither d nor g are present ; j is pyrrolidino , piperidino or azabicyclic moiety ; as well as compounds wherein e is — s —; d is not present ; g is methylene ; and j is an azabicyclic moiety . additional preferred compounds of the invention include those wherein e is — s —; d is not present ; g is —( ch 2 ) n —, wherein n = 1 - 6 , e . g ., methylene , ethylene , propylene , butylene , and the like ; and j is dialkylamino ( e . g ., dimethylamino ), pyrrolidino , piperidino , or an azabicyclic moiety . invention compounds have affinity for acetylcholine receptors . as employed herein , the term “ acetylcholine receptor ” refers to both nicotinic and muscarinic acetylcholine receptors . affinity of invention compounds for such receptors can be demonstrated in a variety of ways , e . g ., via competitive radioligand binding experiments in which the test compounds displace isotopically labeled ligands ( such as nicotine , cytisine , methylcarbamylcholine , quinuclidinyl benzilate , and the like ) from binding sites in mammalian cerebral membranes ( see , e . g ., example 35 ). furthermore , the binding of compounds to acetylcholine receptors can be evaluated as a functional response ( see , e . g ., example 37 ). for example , the activity of invention compounds can be evaluated employing functional assays based on recombinant neuronal acetylcholine receptor expression systems ( see , for example , williams et al ., drug news & amp ; perspectives 7 : 205 - 223 ( 1994 )). test compounds can also be evaluated for their ability to modulate the release of neurotransmitters ( e . g ., dopamine , norepinephrine , and the like ) from rat brain slices ( e . g ., striatum , hippocampus , and the like ). see , e . g ., example 36 . moreover , test compounds can also be evaluated by way of behavioral studies employing animal models of various cns , autonomic and cardiovascular disorders ( see , for example , d &# 39 ; amour and smith , j . pharmacol . exp . ther . 72 : 74 - 79 ( 1941 ) and iwamoto , j . pharmacol . exp . ther . 251 : 412 - 421 ( 1989 ) for animal models of pain ; klockgether and turski , ann . neurol . 28 : 539 - 546 ( 1990 ), colpaert , f ., neuropharmacology 26 : 1431 - 1440 ( 1987 ), ungerstedt and arbuthknott , brain res . 24 : 485 - 493 ( 1970 ), von voigtlander and moore , neuropharmacology 12 : 451 - 462 ( 1973 ), ungerstedt et al ., adv . neurol . 3 : 257 - 279 ( 1973 ), albanese et al ., neuroscience 55 : 823 - 832 ( 1993 ), janson et al ., clin . investig . 70 : 232 - 238 ( 1992 ), sundstrom et al ., brain res . 528 : 181 - 188 ( 1990 ), sershen et al ., pharmacol . biochem . behav . 28 : 299 - 303 ( 1987 ) for animal models of parkinson &# 39 ; s disease ; williams et al ., gastroenterology 94 : 611 - 621 ( 1988 ), miyata et al ., j . pharmacol . exp . ther . 261 : 297 - 303 ( 1992 ), yamada et al ., jpn . j . pharmacol . 58 ( suppl . ): 131 ( 1992 ) for animal models of irritable bowel syndrome ; coyle et al ., neurobehav . toxicol . tetatol . 5 : 617 - 624 ( 1983 ), schartz et al ., science 219 : 316 - 318 ( 1983 ) for animal models of huntington &# 39 ; s disease ; clow et al ., euro . j . pharmacol . 57 : 365 - 375 ( 1979 ), christensen et al ., psychoparmacol . 48 : 1 - 6 ( 1976 ), rupniak et al ., psychopharmacol . 79 : 226 - 230 ( 1983 ), waddington et al ., science 220 : 530 - 532 ( 1983 ) for animal models of tardive dyskinesia ; emerich et al ., pharmacol . biochem . behav . 38 : 875 - 880 ( 1991 ) for animal models of gilles de la tourette &# 39 ; s syndrome ; brioni et al ., eur . j . pharmacol . 238 : 1 - 8 ( 1993 ), pellow et al ., j . neurosci . meth . 14 : 149 ( 1985 ) for animal models of anxiety ; and estrella et al ., br . j . pharmacol 93 : 759 - 768 ( 1988 ) for the rat phrenic nerve model which indicates whether a compound has muscle effects that may be useful in treating neuromuscular disorders ). those of skill in the art recognize that invention compounds may contain one or more chiral centers , and thus can exist as racemic mixtures . for many applications , it is preferred to carry out stereoselective syntheses and / or to subject the reaction product to appropriate purification steps so as to produce substantially optically pure materials . suitable stereoselective synthetic procedures for producing optically pure materials are well known in the art , as are procedures for purifying racemic mixtures into optically pure fractions . in the following reaction schemes , each of a , b , d , e , g and j are as defined above . when any one or more of the r - group substituents ( i . e ., r 1 , r 2 , r 3 , r 4 or r 5 ) are — oh or — sh , it will be readily apparent to those of skill in the art that this functional group . may require the use of “ protecting groups ” ( e . g ., t - butyldimethylsilyl ( t - bdms ), benzyl ( b n ) or tetrahydrophenyl ( thp ), and the like ) during the coupling reaction to “ block ” the reactivity of the r group . similarly , when the r - group is — nh 2 , protecting groups ( e . g ., 9 - fluoromethylcarbonyl ( fmoc ), butoxycarbonyl ( boc ), benzoyloxycarbonyl ( cbz ), and the like ) may be required . furthermore , when j = pyrrolidine , an additional protecting step may be required . for such purpose , boc , cbz , and the like can be employed . hence , subsequent deprotection will be required prior to analysis . a variety of methods can be employed for the preparation of compounds having the general formula z . for example , an example scheme for the production of compounds wherein e represents a sulfur linking moiety are shown in reaction schemes i and ii . all variables used in the schemes presented herein are as defined above , and n ′ and n ″ each fall within the range of 1 - 3 . in reaction scheme i the sulfhydryl derivatives , ( compounds i ) are commercially available ( e . g ., 2 - mercaptopyridine , 4 - mercaptopyridine , aldrich chemical co ., 2 - pyridinemethanethiol , pyrazine specialties inc .) or may readily be prepared by those skilled in the art by selecting the appropriate d moiety ( e . g ., 2 - pyridinemethanethiol , 2 - pyridineethanethiol , barnes , j . h . et al ., eur . j . med . chem . 23 : 211 ( 1988 )). alternatively , the sodium or lithium salt of i can be used to produce compounds of general formula iva or ivb . in this case no base is needed and the reaction can be conducted in a solvent such as methanol or ethanol . reaction times required for this coupling procedure can vary widely and fall in the range of 10 minutes up to about 24 hours . preferred reaction times fall in the range of about one hour . this reaction can be carried out over a wide range of temperatures . temperatures in the range of room temperature are presently preferred . in reaction scheme i , the sulfur compounds ( compounds i ) are effectively contacted with halides or their equivalents , especially chloride or mesylate derivatives ( compounds iia or iib ), optionally bearing g . compounds iia or iib are commercially available ( e . g ., 2 -( 2 - chloroethyl )- 1 - methylpyrrolidine , aldrich chemical co .) or may be prepared from starting materials well - known to those skilled in the art ( see e . g ., wrobel and hejchman , synthesis 5 : 452 ( 1987 ) or gautier et al ., ann . pharm . fr . 30 : 715 ( 1972 )) or , alternatively , the mesylate derivative or the chloro derivative may also be prepared from the corresponding alcohol ( compound iiia or iiib ), according , respectively , to fürst and koller , helv . chim . acta 30 : 1454 ( 1947 ) and tabushi , i ., tetrahedron lett . 293 ( 1970 ). the alcohol derivatives are commercially available ( e . g ., tropinone , aldrich chemical co . ), may be prepared ( e . g ., endo - 7 - methyl - 7 - azabicyclo [ 2 . 2 . 1 ] heptane - 2 - ol , pfister , j . r . et al ., j . pharm . sci . 74 : 108 ( 1985 ); endo - 7 - azabicyclo [ 2 . 2 . 1 ] heptane - 2 - ol , fletcher , j ., j . org . chem . 59 : 1771 ( 1994 ); exo or endo - 9 - methyl - 9 - azabicyclo [ 4 . 2 . 1 ] nonane , campell , h . f . et al ., can . pol . j . chem . 53 : 27 ( 1979 ) or can be obtained by reduction of the corresponding ester using methods well - known to those skilled in the art ( e . g ., 6 - carboxylic acid - 8 - methyl - 8 - azabicyclo [ 3 . 2 . 1 ] octane - methylester , gonzalez at al ., j . am . chem . 117 : 3405 ( 1995 )). similarly , chloro , mesylate or tosylate derivatives of dialkylamines can be used instead of compounds of formula iia or iib . this coupling reaction is promoted by suitable base , such as , for example potassium hydroxide , sodium hydride , sodium ethoxide , potassium carbonate , 1 , 8 - diazatribyclo [ 5 . 4 . 0 ] undec - 7 - ene ( dbu ), and the like . presently preferred base for use in the practice of the present invention is potassium carbonate or sodium hydride . the above - described reaction is typically carried out in a solvent such as methanol , tetrahydrofuran ( thf ), dimethylformamide ( dmf ), and the like . presently preferred solvent for use in the practice of the present invention is dmf or a 50 / 50 mixture of thf and dmf . typically the coupling reaction can be carried out over a wide range of temperatures . temperatures in the range of room temperature to 80 ° c . are presently preferred . reaction times required to effect the desired coupling reaction can vary widely , typically falling in the range of 10 minutes up to about 24 hours . preferred reaction times fall in the range of about 30 minutes to 12 hours . the resulting thioether derivative may be purified and analyzed by techniques well known to those skilled in the art . alternatively , compounds of formula iva or ivb may be prepared following the reaction described in reaction scheme ii . in reaction scheme ii , compound of formula v ( wherein d is selected from methylene or ethylene unit and y ′ is halogen , a mesylate or a tosylate group ) are commercially available or may be readily prepared from starting materials well - known to those skilled in the art . compounds via or vib can be prepared according to reaction scheme iii from the corresponding compound of general formula iia or iib . when y ″ is hydrogen , the coupling reaction is promoted by suitable base , such as , for example potassium hydroxide , sodium hydride , sodium ethoxide , potassium carbonate , 1 , 8 - diazabicyclo [ 5 . 4 . 0 ] undec - 7 - ene ( dbu ), and the like . presently preferred base for use in the practice of the present invention is potassium carbonate or sodium hydride . the above - described reaction is typically carried out in a solvent such as methanol , thf , dmf , and the like . presently preferred solvent for use in the practice of the present invention is dmf or a 50 / 50 mixture of thf and dmf . when y ″ is a sodium or lithium cation , the coupling reaction is conducted directly after the hydrolysis of the thioacetate ( scheme iii ) in the same solvent ( methanol ) in a one pot reaction by addition of one equivalent of compound of general formula v . a method for the preparation of compounds of general formula via or vib is depicted in scheme iii . in step a of reaction scheme iii , compound of general formula iia or iib is contacted with potassium thioacetate , via a nucleophilic substitution well known to those skilled in the art in order to obtain the thioacetate of general formula viia or viib . in step b of the reaction scheme iii , the resulting thioesters ( compound viia or viib ) are hydrolyzed using procedures well know to those of skill in the art , such as litium hydroxide in methanol , sodium methoxide in methanol and the like , to provide the desired thiol derivative of general formula via or vib . exemplary methods for the preparation of compounds having the general formula z , as described hereinabove , wherein e represents a sulfoxide linking moiety (— s ( o )—) or a sulfone linking moiety (— s ( o ) 2 —), are shown in reaction scheme iv . in step a , the resulting thioether derivatives produced , for example , as described in reaction scheme i or ii ( compounds iva or ivb ), may be oxidized to their corresponding sulfoxides ( compounds viiia or viiib ) using about one to about five equivalents of a suitable oxidant , such as , for example , hydrogen peroxide or a hydrogen peroxide derivative such as tert - butyl hydroperoxide , peracids ( such as 3 - chloroperbenzoic acid ), halogen oxide derivatives ( such as sodium metaperiodate ), n - halogenated derivatives ( such as n - bromo or n - chlorosuccidimide ), and the like ( for a review see madesclaire , m ., tetrahedron 42 : 5459 ( 1985 )). presently preferred oxidant for use in the practice of the present invention is about three equivalents of hydrogen peroxide . the above - described reaction is typically carried out in a solvent such as methylene chloride , acetic acid , dioxane , ethanol , methanol , and the like . presently preferred solvent for use in the practice of the present invention is acetic acid . typically the reaction can be carried out over a wide range of temperatures , typically falling in the range of about − 78 ° c . up to reflux . temperatures in the range of about 22 ° c . are presently preferred . reaction times required to effect the desired oxidation reaction can vary widely , typically falling in the range of 10 minutes up to about 24 hours . preferred reaction times fall in the range of about 30 minutes to one hour . the resulting sulfoxides ( compound viiia or viiib ) may be purified and analyzed by techniques well known to those skilled in the art . alternatively , in step b of reaction scheme iv , the thioether derivatives ( compounds iva or ivb ) may be oxidized to their corresponding sulfones ( compounds ixa or ixb ) using procedures similar to those described above for preparing sulfoxides , but employing elevated levels of oxidant and / or elevated reaction temperatures . in the present invention , hydrogen peroxide in acetic acid under reflux is the preferred condition ( r . gaul et al ., j . org . chem . 26 : 5103 ( 1961 )). the resulting sulfones ( compounds ixa or ixb ) are purified and analyzed by techniques well known to those skilled in the art . exemplary methods for the preparation of compounds having the general formula z , as described hereinabove , wherein e is represents an ester linking moiety ( i . e ., — c ( o ) o —), are shown in reaction schemes v and vi . in reaction scheme v , compounds of formula x , wherein d is absent or selected from methylene or ethylene , are commercially available and are well known to those skilled in the art . those compounds not currently available may readily be prepared from starting materials well - known to those skilled in the art . in reaction scheme v , the aryl acid chlorides of formula x are effectively contacted with the primary alcohol compounds of formula iiia or iiib , optionally bearing g , and a base such as dimethylaminopyridine ( dmap ) under anhydrous conditions in an aprotic solvent , such as , for example , methylene chloride ( ch 2 cl 2 ), tetrahydrofuran ( thf ), diethyl ether , benzene , toluene , and the like . compounds of formula iiia or iiib are described in scheme i . similarly , hydroxy derivatives of dialkylamines can be used instead of compounds of formula iiia or iiib . the reaction mixtures are stirred for 1 to 16 hr , with 4 hours preferred , at reaction temperatures within the range of − 78 ° c . up to reflux , with ambient temperatures presently preferred . the resulting esters ( formula xia or xib ) are typically purified and analyzed by techniques well known to those of skill in the art . further , compounds of formula xia or xib may be prepared from aryl carboxylic acid derivatives according to reaction scheme vi . carboxylic acid derivatives xii employed in reaction scheme vi are commercially available or may readily be prepared from well - known starting materials . compounds of formula xii are coupled with compounds of formula iiia or iiib in the presence of triethylamine ( tea ), 1 -( 3 - dimethylaminopropyl )- 3 - ethylcarbodiimide ( edc ) in an aprotic solvent such as methylene chloride ( ch 2 cl 2 ) or chloroform and the like . similarly , hydroxy derivatives of dialkylamines can be used instead of compounds of formula iiia or iiib . the reaction mixtures are stirred for 8 to 16 hr , with 12 hr preferred , at reaction temperatures within the range of − 78 ° c . to reflux , with ambient temperatures presently preferred , to afford compounds xia or xib . the resulting esters are typically purified and analyzed by techniques well known to those of skill in the art . exemplary methods for the preparation of compounds having the general formula z , as described hereinabove , wherein d is present or absent and g is a lower alkenylene , are shown in reaction scheme vii . as illustrated in reaction scheme vii , thio derivatives i ( see scheme i ) are reacted with diethyl chloromethylphosphonate . the reaction is promoted by a suitable base , such as , for example potassium carbonate , sodium hydroxide , sodium ethoxide , sodium hydride and the like in a suitable solvant such as , methanol , ethanol , dmf . presently preferred base for use in the practice of the present invention is potassium carbonate in dimethylformamide ( dmf ). typically this reaction may be carried out over a wide range of temperature . temperatures in the range of 0 ° c . to room temperature are presently preferred . reaction time required to effect the desired reaction can vary widely , typically falling in the range of 10 minutes up to about 24 hours . in the second step compound xiii reacts with the aldehyde or the ketone xiva or xivb under wittig - horner olefination conditions , well - known to those skilled in the art , to form the olefin xva or xvb . compounds xiva or xivb are commercially available ( e . g ., 8 - methyl - 8 - azabicyclo [ 3 . 2 . 1 ] octane - 3 - one , aldrich chemical co . ), may be prepared from starting materials well - know to those skilled in the art ( e . g ., 9 - methyl - 9 - azabicyclo [ 4 . 2 . 1 ] nonane - 2 - one ; wiseman , j . et al ., j . org . chem . 2485 : 13 ( 1985 ); 8 - methyl - 8 - azabicyclo [ 3 . 2 . 1 ] octane - 6 - one , aaron , h . s . et al ., j . heterocycl . chem . 423 : 5 ( 1968 )) or may be prepared according to scheme viii . a method for the preparation of compounds of formula xiv is depicted in scheme viii . in step a of reaction scheme viii , aldehyde xvi is contacted with triethyl phosphonoacetate xvii , via a wittig - horner reaction well known to those skilled in the art in order to obtain the unsaturated ester ( compound xviii ). in step b of reaction scheme viii the resulting unsaturated ester ( compound xviii ) may be reduced to the corresponding saturated ester ( compound xix ) using procedures well known to those skilled in the art , such as catalytic hydrogenation using a pressure of hydrogen , a catalyst such as pto 2 and a solvent such as acetic acid , ethanol , methanol , and the like . in step c of reaction scheme viii the saturated ester ( compound xix ) is contacted with n - methoxy - n - methylamine in the presence of trimethylaluminium in an aprotic solvent such as benzene in order to form the corresponding weinreb amide ( compound xx ) ( levin et al ., synt . com . 12 : 989 ( 1982 )). alternatively the ester ( compound xix ) can be transformed to the corresponding acyl chloride and transformed to the weinred amide using condition well known to those skilled in the art ( weinred et al . tetrahedron lett 22 : 3815 ( 19871 )). in step d of reaction scheme viii compound xx may be reduced to the aldehyde ( compound xxi ) using procedures well know to those skilled in the art , such as lithium aluminium hydride in ether or tetrahydrofuran ( thf ). similarly , aldehyde derivatives of dialkylamines or azabicycloalkanes can be synthesized using the same type of methodology . exemplary methods for the preparation of compounds having the general formula z , as described hereinabove , wherein e is not present , are shown in reaction scheme ix . as illustrated in reaction scheme ix , halogenated derivatives ( compounds xxii ), are reacted with diethyl phosphite in an aprotic solvent such as benzene , toluene , acetonitrile , tetrahydrofuran and the like in the presence of a base such as , sodium hydride , butyl lithium , forming the corresponding wittig - horner reagent ( compounds xxiii ). typically this reaction may be carried out over a wide range of temperatures . temperatures in the range of about 0 ° c . are presently preferred . reaction times required to effect the desired coupling reaction can vary widely , typically falling in the range of 10 minutes up to about 24 hours . preferred reaction times fall in the range of 1 hour . the resulting compounds may be purified and analyzed by techniques well known to those skilled in the art . in step b of reaction scheme ix , the wittig - horner reagent ( compounds xxiii ) are alternatively contacted with an appropriate aldehyde or ketone ( compounds xiva or xivb ; see scheme vii ), via a wittig - horner reaction well - known to those skilled in the art to afford compounds xxiva or xxivb . in step c of reaction scheme xiv , the resulting alkenylene - linker derivatives ( compounds xxiva or xxivb ) may be reduced to their corresponding saturated alkylene derivatives ( compounds xxva or xxvb ) using procedures well known to those of skill in the art , such as exposure to hydrogen using a pd / c catalyst . similiary derivatives of dialkylamines can be synthesized using the same type of methodology . exemplary methods for the preparation of compounds having the general formula z , as described hereinabove , wherein e is represents an oxygen linking moiety are shown in reaction scheme x . in reaction scheme x hydroxypyridine derivatives ( compound xxvi ) are commercially available ( e . g ., 2 - hydroxypyridine , 4 - hydroxypyridine , aldrich chemical co .). compounds of formula iiia and iiib are described in scheme i . mitsunobu &# 39 ; s conditions can be used to obtain the desired compound . this reaction is promoted by diethyl azodicarboxylate or diisopropyl azodicarboxylate in the presence of a phosphine such as triphenylphosphine , tributylphosphine and the like . presently diethyl azodicarboxylate and triphenylphosphine are preferred . the above - described reaction is typically carried out in an aprotic solvent such as tetrahydrofuran ( thf ), ether , benzene , toluene , acetonitrile and the like . presently preferred solvent for the use in the practice of the present invention is tetrahydrofuran ( thf ). typically the reaction can be carried out over a wide range of temperatures , usually in the range of about − 78 ° c ., up to reflux . temperatures in the range of 22 ° c ., are presently preferred . the resulting ether ( compounds xxviia and xviib ) may be purified and analyzed by techniques well known to those skilled in the art . in accordance with another embodiment of the present invention , there are provided pharmaceutical compositions comprising substituted pyridine compounds as described above , in combination with pharmaceutically acceptable carriers . optionally , invention compounds can be converted into non - toxic acid addition salts , depending on the substituents thereon . thus , the above - described compounds ( optionally in combination with pharmaceutically acceptable carriers ) can be used in the manufacture of a medicament for modulating the activity of acetylcholine receptors . pharmaceutically acceptable carriers contemplated for use in the practice of the present invention include carriers suitable for oral , intravenous , subcutaneous , transcutaneous , intramuscular , intracutaneous , inhalation , and the like administration . administration in the form of creams , lotions , tablets , dispersible powders , granules , syrups , elixirs , sterile aqueous or non - aqueous solutions , suspensions or emulsions , patches , and the like , is contemplated . also contemplated is single dose administration , sustained release administration ( e . g ., employing time release formulations , metered delivery , repetitive administration , continuous delivery , and the like ), administration in combination with other active ingredients , and the like . for the preparation of oral liquids , suitable carriers include emulsions , solutions , suspensions , syrups , and the like , optionally containing additives such as wetting agents , emulsifying and suspending agents , sweetening , flavoring and perfuming agents , and the like . for the preparation of fluids for parenteral administration , suitable carriers include sterile aqueous or non - aqueous solutions , suspensions , or emulsions . examples of non - aqueous solvents or vehicles are propylene glycol , polyethylene glycol , vegetable oils , such as olive oil and corn oil , gelatin , and injectable organic esters such as ethyl oleate . such dosage forms may also contain adjuvants such as preserving , wetting , emulsifying , and dispersing agents . they may be sterilized , for example , by filtration through a bacteria - retaining filter , by incorporating sterilizing agents into the compositions , by irradiating the compositions , or by heating the compositions . they can also be manufactured in the form of sterile water , or some other sterile injectable medium immediately before use . invention compounds can optionally be converted into non - toxic acid addition salts . such salts are generally prepared by reacting the compounds of this invention with a suitable organic or inorganic acid . representative salts include the hydrochloride , hydrobromide , sulfate , bisulfate , methanesulfonate , acetate , oxalate , valerate , oleate , laurate , borate , benzoate , lactate , phosphate , tosylate , citrate , maleate , fumarate , succinate , tartrate , napsylate , and the like . such salts can readily be prepared employing methods well known in the art . the invention will now be described in greater detail with reference to the following non - limiting examples . all references cited herein are hereby incorporated by reference . synthesis of invention thioether compounds iva or ivb synthetic scheme i or scheme ii into a two neck flask fitted with a condenser , a thermometer and flushed with argon was placed compound of general formula ii and compound of general formula i ( scheme i ) or compound of general formula vi and compound of general formula v ( scheme ii ), potassium carbonate ( 3 eq ) and dry dimethylformamide ( 3 ml / mmol ). the reaction mixture was either stirred at room temperature overnight or heated at 70 ° c . for 30 min . the mixture was filtered through celite to remove excess potassium carbonate , hydrolyzed ( 5 ml / mmol ) and extracted three times with ethyl acetate ( 4 ml / mmol ). the organic layer were combined , washed with brine ( 3 × 5 ml / mmol ), dried ( mgso 4 ) and concentrated under vacuum ( 15 mm hg ) to give an oil . the crude material was purified via chromatography on silica using a gradient of chloroform and methanol as eluant . the pure compound of general formula iv was converted to the hcl salt . into a three neck flask fitted with a condenser , an addition funnel , a thermometer and flushed with argon was placed sodium hydride ( 1 . 1 eq ) and thf ( 1 . 5 ml / mmol ). the thiol derivative of general formula i ( scheme i ) or general formula vi ( scheme ii ) ( 1 eq ) previously dissolved in thf ( 0 . 5 ml / mmol ) was added dropwise at 0 ° c . after the addition was completed the reaction mixture was allowed to stir at this temperature for 15 min and compound of general formula ii ( scheme i ) or general formula v ( scheme ii ) ( 1 eq ) previously dissolved in dry dmf ( 2 ml / mmol ) was added dropwise . the mixture was allowed to warm up to room temperature , heated at 70 ° c . for 1 . 5 hours , cooled to room temperature and stirred overnight . after hydrolysis with water ( 5 ml / mmol ) and extraction three times with etoac ( 5 ml / mmol ), the organic layers were combined , washed with brine ( 3 × 5 ml / mmol ), dried ( mgso4 ) and concentrated under vacuum ( 15 mm hg ) to give an oil . the crude material was purified via chromatography on silica using a gradient of chloroform and methanol as eluant . the resulting pure compound of general formula iv was converted to the hcl salt . the sodium or lithium salt of compound of general formula i ( scheme i ) or general formula vi ( scheme ii ) ( obtained by hydrolysis with a normal aqueous solution of lioh ( 30 min to 1 hour ; 1 eq ) of the corresponding thioacetate ( see method d )) and one equivalent of compound of general formula ii ( scheme i ) or general formula v ( scheme ii ) were mixed together in methanol ( 2 ml / mmol ). the reaction mixture was stirred at room temperature and monitored by tlc until completion . the solvent was removed under vacuum . water was added to the residue and the mixture was extracted three times with etoac ( 4 ml / mmol ). the organic layers were combined , washed with brine ( 5 ml / mmol ), dried ( mgso 4 ) and concentrated under vacuum ( 15 mm hg ) to give an oil . the crude material was purified via chromatography on silica using a gradient of chloroform and methanol as eluant . the resulting pure compound of general formula iv was converted to the hcl salt . into a two neck flask fitted with a condenser , a thermometer and flushed with argon was placed the halide or mesylate derivative of general formula ii ( 1 eq ) or general formula v , potassium thioacetate ( 1 . 2 eq ), dry dimethylformamide ( dmf ) ( 1 . 5 ml / mmol ) or dry methylene chloride containing about 10 to 20 % of dmf and a base such as potassium carbonate ( 3 eq ) or diisopropylethyl amine ( 1 . 5 eq ). the reaction mixture was stirred at room temperature and monitored by tlc until completion . in general the reaction is complete after 2 to 3 hours ( some compounds require 30 min at 70 ° c .) the mixture was hydrolyzed and extracted three times with ethyl acetate ( 4 ml / mmol ). the organic layers were combined , washed with brine ( 3 × 5 ml / mmol ), dried ( mgso 4 ) and concentrated under reduced pressure ( 15 mm hg ). the resulting oil was purified via flash chromatography on silica using a gradient of choroform and methanol to provide the desired thioacetate . the resulting thioacetate is hydrolyzed using sodium hydroxide ( 1 . 1 eq ) or lithium hydroxide ( 1 . 1 eq ) in methanol ( 1 . 5 ml / mmole ). in general the reaction is complete in 30 min . the solvent is removed under vacuum ( 15 mm hg ) and water was added . the ph is adjusted to 6 - 7 by addition of hcl ( 1n ) and the aqueous solution is extracted three times with etoac ( 4 ml / mmol ). the organic layers are combined , washed with brine ( 5 ml / mmol ), dried ( mgso 4 ) and concentrated under vacuum ( 15 mm hg ) to produce the desired thiol - derivative in high yield . 2 -( 2 - chloroethyl )- 1 - methylpyrrolidine ( 4 . 99 g , 27 . 0 mmol ), 4 - mercaptopyridine ( 3 . 0 g ; 27 . 0 mmol ), potassium carbonate ( 11 . 19 g , 80 . 96 mmol ) and dmf ( 80 ml ) were combined and stirred at room temperature for 2 days , yielding 2 . 96 g ( 13 . 3 mmol , 49 %) of the desired compound which was converted to the hydrochloride salt . 1 h nmr ( 300 mhz , cd 3 od ) δ 8 . 56 ( d , j = 7 hz , 2h ), 7 . 96 ( d , j = 7 hz , 2h ), 3 . 72 ( m , 1h ), 3 . 58 ( m , 1h ), 3 . 41 ( m , 2h ), 3 . 20 ( m , 2h ), 22 . 96 ( s , 3h ), 2 . 48 ( m , 1h ), 2 . 14 ( m , 3h ), 1 . 93 ( m , 1h ); 13 c ( 75 . 5 mhz , cd 3 od ) δ 165 . 9 , 140 . 9 , 123 . 8 , 69 . 3 , 57 . 5 , 40 . 2 , 30 . 6 , 30 . 2 , 28 . 8 , 22 . 7 ; mp 186 . 5 - 187 . 5 ° c . ; c h n analysis c 12 h 18 n 2 s . 2 . 5hcl . 2 -( 2 - chloroethyl )- 1 - methylpyrrolidine ( 6 . 64 g , 45 . 0 mmol ), 2 - mercaptopyridine ( 5 . 0 g ; 45 . 0 mmol ), sodium hydride ( 1 . 62 g , 67 . 47 mmol ) gave to 7 . 03 g ( 31 . 6 mmol , 85 %) of the desired compound which was converted to the hydrochloride salt . 1 h nmr ( 300 mhz , cd 3 od ) δ 8 . 72 ( d , j = 7 hz , 1h ), 8 . 49 ( t , j = 7 hz , 1h ), 8 . 13 ( d , j = 7 hz , 1h ), 7 . 18 ( t , j = 7 hz , 1h ), 3 . 8 ( m , 1h ), 3 . 6 ( m , 2h ), 3 . 25 ( m , 1h ), 3 . 03 ( s , 3h ), 2 . 55 ( m , 1h ), 2 . 2 ( m , 3h ), 2 . 0 ( m , 1h ); 13 c nmr ( 75 . 5 mhz , cd 3 od ) δ 157 . 9 , 146 . 4 , 144 . 3 , 126 . 8 , 123 . 9 , 69 . 2 , 57 . 5 , 40 . 1 , 30 . 9 , 30 . 6 , 29 . 6 , 22 . 7 ; mp 165 - 167 ° c . into a 500 ml round - bottomed flask equipped with a magnetic stirring bar was placed ( 4 - pyridyl ) methanethiol from the previous synthesis ( 62 mmol ) and thf ( 120 ml ). the resulting solution was cooled to 0 ° c . in an ice bath . sodium hydride ( 5 . 0 g of a 60 % dispersion in mineral oil , 125 mmol ) was added to the cold solution which resulted in vigorous gas evolution . after 15 minutes gas evolution had subsided and a yellow suspension had formed . 2 -( 2 - chloroethyl )- 1 - methylpyrrolidine hydrochloride ( 8 . 7 g , 47 mmol ) in dmf ( 100 ml ) was added via a cannula to the reaction mixture at 0 ° c . the flask and cannula were then rinsed with additional dmf ( 20 ml ) to insure complete transfer . after stirring the mixture for 45 minutes at 0 ° c ., tetrabutylammonium iodide ( 688 mg ) was added . the ice bath was then removed and the reaction was allowed to warm to 25 ° c . after 6 hours at 25 ° c . the reaction was quenched by the addition of glacial acetic acid ( 8 . 0 ml , 140 mmol ) and water ( 100 ml ) and the mixture was concentrated in vacuo . to the resulting brown solution was added saturated aqueous sodium bicarbonate solution ( 100 ml ) and ethyl acetate ( 300 ml ) and the layers were separated . the aqueous phase was extracted with ethyl acetate ( 4 × 100 ml ) and the combined organic extracts were washed with water ( 100 ml ), brine ( 100 ml ), and dried over sodium sulfate . the drying agent was removed by filtration and the filtrate was concentrated in vacuo to afford 15 . 87 g of a biphasic brown oil . the crude product was chromatographed on silica gel eluting with chloroform : methanol ( gradient elution at 15 : 1 , 10 : 1 , 7 : 1 , 5 : 1 , and 3 : 1 ). fractions from the column containing pure product were concentrated to afford a dark oil ( 2 . 02 g , 14 %). the pure fractions could be further purified by kügelrohr distillation ( 200 ° c ., 0 . 5 torr ) to afford a clear liquid that was analytically pure . 1 h nmr ( 300 mhz , cd 3 od ) δ 8 . 60 ( m , 2h ), 7 . 43 ( m , 2h ), 3 . 77 ( s , 2h ), 3 . 01 ( m , 1h ), 2 . 54 - 2 . 32 ( m , 2h ), 2 . 26 ( s , 3h ), 2 . 16 ( m , 2h ), 2 . 02 - 1 . 85 ( m , 2h ), 1 . 72 ( m , 2h ), 1 . 51 - 1 . 27 ( m , 2h ); 13 c nmr ( 75 . 5 mhz , cd 3 od ) δ 151 . 3 , 150 . 1 , 125 . 8 , 66 . 7 , 57 . 9 , 40 . 6 , 35 . 8 , 34 . 1 , 31 . 3 , 29 . 5 , 22 . 5 ; lrms ( ei ) m / e 236 ( c 13 h 20 n 2 s , m + ). prepared by a procedure analogous to that described for 2 -[ 2 -( 4 - pyridyl ) methanethioethyl ]- 1 - methylpyrrolidine ( see example 7 ) but with the appropriate starting material to provide the 2 - isomer . yellow oil , ( 3 . 03 g , 75 %). 1 h nmr ( 300 mhz , cdcl 3 ) δ 8 . 53 ( m , 1h ), 7 . 65 ( ddd , j = 2 , 8 , 8 hz , 1h ), 7 . 37 ( d , j = 8 hz , 1h ), 7 . 16 ( m , 1h ), 3 . 85 ( s , 2h ), 3 . 03 ( m , 1h ), 2 . 62 - 2 . 39 ( m , 2h ), 2 . 27 ( s , 3h ), 2 . 16 - 2 . 03 ( m , 2h ), 1 . 97 - 1 . 81 ( m , 2h ), 1 . 79 - 1 . 58 ( m , 2h ), 1 . 57 - 1 . 33 ( m , 2h ) ; 13 c nmr ( 75 . 5 mhz , cdcl 3 ) δ 158 . 8 , 149 . 3 , 136 . 7 , 123 . 0 , 121 . 9 , 65 . 2 , 57 . 2 , 40 . 4 , 38 . 4 , 33 . 4 , 30 . 3 , 28 . 7 , 21 . 8 . 1 -( 2 - chloropropyl )- piperidine hydrochloride ( 2 . 51 g , 12 . 66 mmol ), 4 - mercaptopyridine ( 1 . 55 g , 13 . 94 mmol ), potassium carbonate ( 5 . 25 g , 38 . 0 mmol ) and dmf ( 40 ml ) were combined and stirred at room temperature for 24 hours , yielding 1 . 72 g ( 7 . 27 mmol , 57 %) of the desired compound which was converted to . the hydrochloride salt . 1 h nmr ( 300 mhz , cd 3 od ) δ 7 . 90 ( d , j = 7 hz , 2h ), 7 . 21 ( d , j = 7 hz , 2h ), 3 . 46 ( m , 2h ), 3 . 19 - 3 . 28 ( m , 4h ), 2 . 89 ( m , 2h ), 2 . 20 ( m , 2h ), 1 . 74 - 1 . 88 ( m , 6h ); 13 c nmr ( 75 . 5 mhz , cd 3 od ) δ 166 . 3 , 141 . 1 , 124 . 3 , 124 . 1 , 56 . 9 , 54 . 8 , 29 . 3 , 24 . 7 , 24 . 3 , 23 . 1 ; lrms ( ei ) m / e 236 ( m + ); mp 91 - 92 ° c . prepared according to the general procedure c ( see example 3 ) with 1 -( 2 - chloroethyl )- piperidine hydrochloride ( 1 . 2 g , 6 . 5 mmol ), 4 - pyrididemethane thioacetate ( 1 . 1 g , 6 . 58 mmol ), lioh ( 1n , 6 . 60 mmol ) and meoh ( 50 ml ), yielding 0 . 96 g ( 4 . 06 mmol , 62 %) of the desired compound . 1 h nmr ( 300 mhz , cdcl 3 ) δ 8 . 54 ( d , j = 7 hz , 2h ), 7 . 29 ( d , j = 7 hz , 2h ), 3 . 69 ( s , 2h ), 2 . 42 - 2 . 68 ( m , 6h ), 1 . 41 - 1 . 71 ( m , 6h ) ; lrms ( ei ) m / e 236 ( m + ). prepared according to the general procedure c ( see example 3 ) with 1 -( 2 - chloropropyl )- piperidine hydrochloride ( 1 . 5 g , 7 . 5 mmol ), 4 - pyrididemethane thioacetate ( 1 . 05 g , 6 . 33 mmol ), lioh ( 1n , 7 . 0 mmol ) and meoh ( 40 ml ), yielding 0 . 61 g ( 2 . 44 mmol , 38 . 5 %) of the desired compound . 1 h nmr ( 300 mhz , cdcl 3 ) δ 8 . 54 ( d , j = 7 hz , 2h ), 7 . 25 ( d , j = 7 hz , 2h ), 3 . 66 ( s , 2h ), 2 . 30 - 2 . 45 ( m , 8h ), 1 . 41 - 1 . 76 ( m , 8h ); lrms ( ei ) m / e 250 ( m + ). mesylate derivative of tropinol ( 6 . 16 g , 28 . 1 mmol ), 2 - mercaptopyridine ( 3 . 2 g , 28 . 6 mmol ), sodium hydride ( 1 . 7 g , 68 . 0 mmol ) were combined , producing 2 . 75 g ( 11 . 76 mmol , 42 %) of the desired compound which was converted to the hydrochloride salt . 1 h nmr ( 300 mhz , cd 3 od ) δ 8 . 45 ( m , 1h ), 7 . 66 ( t , j = 7 hz , 1h ), 7 . 27 ( d , j = 7 hz , 1h ), 7 . 13 ( t , j = 7 hz , 1h ), 4 . 3 ( m , 1h ), 3 . 96 ( s , 2h ), 2 . 83 ( s , 3h ), 2 . 05 - 2 . 38 ( m , 8h ); lrms ( ei ) m / e 234 ( m + ); mp 201 - 205 ° c . endo - 3 - thio - 8 - methyl - 8 - azabicyclo [ 3 . 2 . 1 ] octane ( 0 . 35 g , 2 . 2 mmol ), 2 - picolyl chloride hydrochloride ( 0 . 42 g , 2 . 6 mmol ), sodium hydride ( 0 . 12 g , 5 mmol ) were combined , producing 0 . 19 g ( 0 . 77 mmol , 35 %) of the desired compound which was converted to the hydrochloride salt . 1 h nmr ( 300 mhz , cd 3 od ) δ 8 . 6 ( m , 1h ), 8 . 5 ( m , 1h ), 7 . 9 ( m , 1h ), 7 . 6 ( m , 1h ), 4 . 4 ( m , 2h ), 3 . 8 ( m , 2h ), 2 . 6 ( s 3h ), 1 . 8 - 2 . 2 ( m , 8h ); lrms ( ei ) m / e 248 ( m + ); mp 204 - 206 ° c . to a flask containing n - benzyl - 3 - hydroxypyridinium bromide ( 50 g , 226 mmol ), methylacrylate ( 203 ml , 2 . 26 mol ) and triethylamine ( 63 ml , 452 mmol ) were added 2 spatulas of hydroquinone . the yellow suspension was then stirred at 70 ° c . for 20 h . the reaction mixture was allowed to cool to 25 ° c . and the solids were removed by filtration . the filtrate was concentrated in vacuo and dried to afford a brown oil ( 60 g , 98 %). 1 h nmr ( 300 mhz , cdcl 3 ): δ 7 . 28 ( m , 5h ), 6 . 98 ( q , j = 5 . 1 hz , 1h ), 6 . 13 ( t , j = 10 hz , 1h ), 3 . 78 ( m , 8h ), 2 . 43 ( m , 3h ). a parr bottle was charged with endo -, exo - methyl 2 - oxo - 8 -( phenylmethyl )- 8 - azabicyclo [ 3 . 2 . 1 ] oct - 3 - ene - 6 - carboxylate ( 27 . 1 g , 100 mmol ), 10 % pd — c ( 2 g ), boc anhydride ( 32 . 7 g , 150 mmol ) and methanol ( 180 ml ). the mixture was hydrogenated under h 2 ( g ) at 30 psi for 5 h after which time the reaction was complete as indicated by t . l . c . the reaction mixture was filtered through celite and concentrated in vacuo to afford ca . 30 g of an orange oil . this was dissolved in small volume of toluene and purifed by chromatography on silica gel using etoac : hexane ( 6 : 1 to 1 : 1 ) as eluant to afford the endo isomer ( 7 . 43 g ) as a yellow liquid , and then the exo isomer ( 9 . 81 g ) as colorless solid . some mixed fractions were also isolated ( 6 . 54 g ); total yield : 84 %. 1 h nmr ( 300 mhz , cdcl 3 ): δ endo : 4 . 59 ( m , 1h ), 4 . 34 ( m , 1h ), 3 . 78 ( s , 3h ), 3 . 37 ( m , 1h ), 2 . 41 ( m , 5h ), 1 . 83 ( m , 1h ), 1 . 45 ( s , 10h ); exo : 4 . 56 ( m , 2h ), 3 . 74 ( s , 3h ), 2 . 96 ( dd , j = 5 . 4 hz , 1h ), 2 . 36 ( m , 4h ), 1 . 92 ( m , 2h ), 1 . 44 ( s , 10h ). to a solution of endo - methyl 2 - oxo - 8 -( tertbutyloxycarbonyl )- 8 - azabicyclo [ 3 . 2 . 1 ] octane - 6 - carboxylate ( 4 . 51 g , 15 . 9 mmol ) in acetic acid ( 80 ml ) was added p - toluenesulfonhydrazide ( 5 . 93 g , 31 . 8 mmol ) and the yellow solution was stirred at 25 ° c . for 18 h . water ( 80 ml ) was added and the solution was stirred at 25 ° c . for 30 min . to afford a colorless precipitate . the solid was isolated by filtration , diluted with methanol - toluene , concentrated and dried in vacuo to afford the tosylhydrazone of the endo ester as a colorless solid ( 6 . 00 g , 83 %). 1 h nmr ( 300 mhz , cdcl 3 ): δ 7 . 84 ( m , 2h ), 7 . 25 ( m , 6h ), 4 . 52 ( m , 2h ), 3 . 75 ( s , 3h ), 3 . 24 ( m , 1h ), 2 . 30 ( m , 11h ), 1 . 31 ( s , 9h ). to a solution of the endo tosylhydrazone derivative ( 3 g , 6 . 6 mmol ) in methanol ( 60 ml ) was added a solution of zinc chloride ( 630 mg , 4 . 63 mmol ) and sodium cyanoborohydride ( 584 mg , 9 . 3 mmol ) in methanol ( 30 ml ) the reaction mixture was heated under reflux for 3 h and then concentrated in vacuo . ethyl acetate and water were added , the reaction mixture was acidified to ph 1 with hcl ( 1m ) then basified to ph 9 with solid potassium carbonate . the combined organic extracts were washed with a saturated solution of sodium potassium tartrate , then brine , dried over magnesium sulfate , filtered and concentrated to afford a yellow oil ( 1 . 8 g ). the crude material was purified by chromatography on silica gel using etoac : hexane ( 6 : 1 ) as eluant to afford the endo ester as a colorless oil ( 1 . 00 g , 57 %) which solidified after 18 h . 1 h nmr ( 300 mhz , cd 3 od ): δ 4 . 28 ( m , 1h ), 4 . 17 ( m , 1h ), 3 . 71 ( s , 3h ), 3 . 27 ( m , 1h ), 2 . 20 ( m , 2h ), 1 . 64 ( m , 6h ), 1 . 47 ( s , 9h ); 13 c nmr ( 75 . 5 mhz , cd 3 od ): δ 173 . 7 , 154 . 7 , 81 . 0 , 57 . 5 - 56 . 7 ( rot ), 55 . 5 - 54 . 6 ( rot ), 47 . 3 - 46 . 8 ( rot ), 31 . 8 - 31 . 1 ( rot ), 30 . 8 - 30 . 1 ( rot ), 28 . 6 , 28 . 4 - 27 . 8 ( rot ), 17 . 5 . anal . calcd . for c 14 h 23 o 4 n : c , 62 . 43 ; h , 8 . 61 ; n , 5 . 20 %. found : c , 62 . 35 , h , 8 . 57 , n , 5 . 25 %. lrms 269 ( m + ). a suspension of lithium aluminum hydride ( 4 . 53 g , 120 mmol ) in dry thf ( 80 ml ) was stirred for 10 min at 25 ° c . then cooled to 0 ° c . endo - methyl 8 -( tertbutyloxycarbonyl )- 8 - azabicyclo [ 3 . 2 . 1 ] octane - 6 - carboxylate ( 6 . 41 g , 23 . 8 mmol ) was added and the solution was allowed to warm to ambient temperature then stirred at 25 ° c . for 24 h . the reaction was quenched by adding water ( 4 . 5 ml ), then 15 % aq . naoh ( 4 . 5 ml ), then water ( 9 ml ). the resulting precipitate was removed by filtration and the fitrate concentrated in vacuo to afford an oil ( 6 . 1 g ). this material was purified by chromatography on silica gel using etoac : hexane ( 4 : 1 to 1 : 1 ) as eluant to afford the endo alkanol as a colorless oil ( 5 . 16 g , 90 %) which solidified after 18 h . 1 h nmr ( 300 mhz , cd 3 od ): δ 4 . 15 ( m , 1h ), 4 . 04 ( m , 1h ), 3 . 70 ( m , 2h ), 2 . 45 ( m , 1h ), 2 . 17 ( m , 1h ), 1 . 73 ( m , 3h ), 1 . 46 ( s , 9h ), 1 . 42 ( m , 4h ); 13 c nmr ( 75 . 5 mhz , cd 3 od ): δ 155 . 0 , 80 . 6 , 62 . 1 , 56 . 9 - 56 . 0 ( rot ), 55 . 3 - 54 . 3 ( rot ), 45 . 3 - 44 . 9 ( rot ), 31 . 7 - 30 . 9 ( rot ), 29 . 0 , 26 . 7 , 26 . 1 , 18 . 2 ; anal . calcd . for c 13 h 23 o 3 n : c , 64 . 70 ; h , 9 . 61 ; n , 5 . 80 %. found : c , 64 . 60 , h , 9 . 55 , n , 5 . 83 %. lrms 241 ( m + ). in a flask containing endo - 6 -( hydroxymethylene )- 8 -( tertbutyloxycarbonyl )- 8 - azabicyclo [ 3 . 2 . 1 ] octane ( 4 g , 16 . 6 mmol ) in methylene chloride ( 400 ml ) was added triethylamine ( 3 . 7 ml , 26 . 5 mmol ), toluenesulfonyl chloride ( 5 . 04 g , 26 . 5mmol ) and n , n - dimethylaminopyridine ( 500 mg ). the solution was stirred at 25 ° c . for 22 h before the reaction mixture was concentrated and water ( 100 ml ) was added . the solution was extracted with ethyl acetate ( 3 × 150 ml ), the organic phase washed with water ( 50 ml ), then brine ( 50 ml ), dried over magnesium sulfate , filtered and concentrated in vacuo . the crude product was chromatographed on silica gel with etoac : hexane ( 6 : 1 to 3 : 1 ) as eluant to afford the endo toluenesulfonyl ester as a colorless solid ( 5 . 89 g , 89 %). 1 h nmr ( 300 mhz , cd 3 od ): δ 7 . 81 ( d , j = 8 hz , 2h ), 7 . 46 ( d , j = 8 hz , 2h ), 4 . 14 ( m , 3h ), 3 . 95 ( bs , 1h ), 2 . 52 ( bs , 1h ), 2 . 45 ( s , 3h ), 2 . 10 ( m , 1h ), 1 . 50 ( m , 7h ), 1 . 47 ( s , 9h ); 13 c nmr ( 75 . 5 mhz , cd 3 od ): δ 154 . 8 , 146 . 7 , 134 . 2 , 131 . 2 , 129 . 1 , 80 . 9 , 70 . 7 , 56 . 6 - 55 . 7 ( rot ), 55 . 2 - 54 . 3 ( rot ), 41 . 7 - 41 . 2 ( rot ), 31 . 1 - 30 . 4 ( rot ), 28 . 7 , 26 . 5 - 25 . 8 ( rot ), 21 . 6 , 17 . 8 ; anal . calcd . for c 20 h 29 o 5 ns : c , 60 . 74 ; h , 7 . 39 ; n , 3 . 54 %. found : c , 60 . 67 , h , 7 . 37 , n , 3 . 59 %. 2 - mercaptopyridine ( 551 mg , 4 . 95 mmol ) was added to a slurry of nah ( 198 mg of a 60 % dispersion in oil , 4 . 95 mmol ) in dry thf ( 10 ml ) under ar ( g ). the suspension was stirred at 25 ° c . for 10 min . before the endo - 6 -( toluenesufonyloxymethylene )- 8 -( tertbutyloxycarbonyl )- 8 - azabicyclo [ 3 . 2 . 1 ] octane ( 1 g , 2 . 5 mmol ) in dmf ( 6 ml ) was added . the resulting clear , yellow solution was stirred at 70 ° c . for 18 h . the reaction was allowed to cool to 25 ° c . and water ( 10 ml ) was added . the solution was extracted with ethyl acetate ( 3 × 20 ml ), the combined organic phase was washed with water ( 3 × 10 ml ), brine ( 2 × 10 ml ), dried over magnesium sulfate , filtered and concentrated in vacuo to afford a yellow oil ( 1 . 1 g ). the crude product was chromatographed on silica gel with etoac : hexane ( 8 : 1 ) as eluant to afford the boc - protected endo 2 - thiopyridine as a colorless oil ( 740 mg , 88 %). 1 h nmr ( 300 mhz , cdcl 3 ): δ 8 . 42 ( m , 1h ), 7 . 47 ( m , 1h ), 7 . 16 ( m , 1h ), 6 . 98 ( m , 1h ), 4 . 11 ( m , 2h ), 3 . 47 ( m , 1h ), 3 . 24 ( dd , j = 8 . 4 , 1h ), 1 . 72 ( m , 6h ), 1 . 46 ( m , 11h ); 13 c nmr ( 75 . 5 mhz , cd 3 od ): δ 159 . 7 , 154 . 5 , 149 . 9 , 137 . 3 , 123 . 0 , 120 . 4 , 80 . 3 , 57 . 3 - 56 . 3 ( rot ), 55 . 1 - 54 . 2 ( rot ), 41 . 7 - 41 . 2 ( rot ), 34 . 1 - 33 . 5 ( rot ), 31 . 0 - 30 . 3 ( rot ), 30 . 2 , 26 . 2 - 25 . 6 ( rot ), 17 . 7 . the boc - protected endo - 2 - thiopyridine ( 710 mg , 2 . 12 mmol ) was dissolved in methylene chloride ( 15 ml ) and hcl in dioxane ( 9 . 6 ml , 38 mmol ) was added . the solution was stirred at 25 ° c . for 40 min and then concentrated in vacuo to afford a yellow foam ( 440 mg ) . this material was purified by chromatography on silica gel with chcl 3 : meoh ( 10 : 1 to2 : 1 ) as eluant to afford a yellow sticky solid ( 635 mg ). 1 h nmr ( 300 mhz , cd 3 od ): δ 8 . 56 ( m , 1h ), 8 . 07 ( m , 1h ), 7 . 76 ( m , 1h ), 7 . 48 ( m , 1h ), 4 . 05 ( m , 1h ), 3 . 95 ( bs , 1h ), 3 . 60 ( m , 2h ), 2 . 87 ( m , 2h ), 2 . 47 ( m , 2h ), 1 . 99 ( m , 4h ), 1 . 75 ( m , 3h ); 13 c nmr ( 75 . 5 mhz , cd 3 od ): δ 158 . 3 , 146 . 9 , 143 . 1 , 125 . 8 , 122 . 9 , 58 . 5 , 56 . 8 , 40 . 0 , 32 . 2 , 30 . 7 , 29 . 3 , 24 . 7 , 16 . 8 ; lrms 234 ( m + ). prepared according to the procedure described for the endo isomer ( see example 16 ) with the appropriate exo isomer starting material . crude yield 19 . 43 g , 94 %, carried on to the next step without further purification . prepared according to the procedure described for the endo isomer ( see example 17 ) using the appropriate exo isomer starting material . yield : 5 . 14 g , 45 % over two steps from the ketone . 1 h nmr ( mixture of rotamers ) ( 300 mhz , cdcl 3 ) δ 4 . 50 - 4 . 19 ( m , 2h ), 3 . 69 ( s , 3h ), 2 . 84 ( dd , j = 5 , 9 hz , 1h ), 2 . 51 - 2 . 27 . ( m , 1h ), 1 . 90 - 1 . 39 ( m , with embedded s at 1 . 46 , 16h ); lrms ( ei ) m / e 269 ( c 14 h 23 no 4 , m + ). prepared according to the procedure described for the endo isomer ( see example 18 ) using the appropriate exo isomer starting material . colorless solid , yield : 2 . 79 g , 100 %. 1 h nmr ( mixture of rotamers ) ( 300 mhz , cdcl 3 ) δ 4 . 26 ( m , 0 . 5h ), 4 . 16 ( m , 0 . 5h ), 4 . 06 ( br s , 0 . 5h ), 3 . 98 ( br s , 0 . 5h ), 3 . 52 - 3 . 34 ( m , 2h ), 2 . 28 - 2 . 14 ( m , 1h ), 1 . 95 ( m , 0 . 25h ), 1 . 86 - 1 . 37 ( m with embedded s at 1 . 47 , 17h ); 13 c nmr ( mixture of rotamers ) ( 75 . 5 mhz , cdcl 3 ) δ 154 . 2 , 154 . 0 , 79 . 3 , 79 . 1 , 65 . 7 , 65 . 3 , 56 . 6 , 55 . 7 , 54 . 5 , 53 . 6 , 53 . 4 , 50 . 4 , 44 . 2 , 43 . 5 , 31 . 4 , 31 . 0 , 30 . 6 , 30 . 4 , 29 . 8 , 28 . 4 , 17 . 1 , 17 . 0 ; lrms ( ei ) m / e 241 ( c 13 h 23 no 3 , m + ). prepared according to the procedure described for the endo isomer ( see example 19 ) using the appropriate exo isomer starting material . yield : 4 . 0 g , 90 %. 1 h nmr ( mixture of rotamers ) ( 300 mhz , cdcl 3 ) δ 7 . 79 ( d , j = 8 hz , 2h ), 7 . 35 ( d , j = 8 hz , 2h ), 4 . 19 ( m , 0 . 5h ), 4 . 08 ( m , 0 . 5h ), 3 . 94 - 3 . 66 ( m , 3h ), 2 . 47 - 2 . 32 ( m with embedded br s at 2 . 45 , 4h ), 1 . 87 - 1 . 52 ( m , 5h ), 1 . 49 - 1 . 32 ( m , 12h ). prepared according to the procedure described for the endo isomer ( see example 20 ) using the appropriate exo isomer starting material . yield : 751 mg , 86 %. 1 h nmr ( mixture of rotamers ) ( 300 mhz , cdcl 3 ) δ 8 . 41 ( m , 1h ), 7 . 47 ( m , 1h ), 7 . 16 ( m , 1h ), 6 . 98 ( m , 1h ), 4 . 31 ( m , 0 . 5h ), 4 . 17 ( m , 0 . 5h ), 4 . 08 ( br s , 0 . 5h ), 4 . 02 ( m , 0 . 5h ), 3 . 23 - 3 . 06 ( m , 2h ), 2 . 41 - 2 . 30 ( m , 1h ), 2 . 02 - 1 . 35 ( m with embedded s at1 . 48 & amp ; 1 . 45 , 17h ). prepared according to the procedure described for the endo isomer ( see example 21 ) using the appropriate exo isomer starting material . yield : 528 mg , 78 %. 1 h nmr ( 300 mhz cd 3 od ) δ 8 . 65 ( d , j = 6 hz , 1h ), 8 . 39 ( app t , j = 7 hz , 1h ), 8 . 08 ( d , j = 8 hz , 1h ), 7 . 74 ( app t , j = 7 hz , 1h ), 4 . 11 ( br d , j = 6 hz , 1h ), 4 . 01 ( br s , 1h ), 3 . 68 - 3 . 49 ( m , 2h ), 2 . 75 - 2 . 63 ( br s , 1h ), 2 . 37 ( m , 1h ), 2 . 08 - 1 . 62 ( m , 7h ); 13 c nmr ( 75 . 5 mhz , cd 3 od ) δ 157 . 6 , 146 . 6 , 144 . 1 , 127 . 0 , 124 . 0 , 61 . 3 , 58 . 0 , 40 . 4 , 37 . 3 , 34 . 6 , 29 . 4 , 28 . 9 , 16 . 5 ; lrms ( ei ) m / e 234 ( c 13 h 18 n 2 s , free base m + ). prepared following the general procedure b ( see example 7 ) using endo - 6 -( toluenesufonyloxymethylene )- 8 -( tertbutyloxycarbonyl )- 8 - azabicyclo [ 3 . 2 . 1 ] octane and ( 4 - pyridyl ) methanethiol to provide the product as a pale yellow oil ( 687mg , 80 %). 1 h nmr ( 300 mhz , cd 3 od ) δ 8 . 46 ( d , j = 6 . 0 , 2h ), 7 . 44 ( d , j = 5 . 8 , 2h ), 4 . 12 ( m , 1h ), 3 . 93 ( m , 1h ), 3 . 80 ( s , 2h ), 2 . 61 ( m , 2h ), 2 . 41 ( m , 1h ), 2 . 25 ( m , 1h ), 1 . 69 ( m , 3h ), 1 . 54 ( m , 2h ), 1 . 45 ( s , 9h ), 1 . 33 ( m , 2h ). prepared by a procedure analogous to that described previously ( see preparation of endo - 6 -( 2 - pyridinethiomethylene )- 8 - h - 8 - azabicyclo [ 3 . 2 . 1 ] octane hydrochloride ; see example 21 ) with endo - 6 -[( 4 - pyridyl ) methanethiomethylene ]- 8 -( tertbutyloxycarbonyl )- 8 - azabicyclo [ 3 . 2 . 1 ] octane as the starting material . the product dihydrochloride salt was isolated as a yellow solid ( 540 mg ). mp : & gt ; 205 ° c . ; 1 h nmr ( 300 mhz , cd 3 od ) δ 8 . 87 ( d , j = 6 . 5 hz , 2h ), 8 . 13 ( d , j = 6 . 5 hz , 2h ), 4 . 13 ( s , 2h ), 4 . 01 ( m , 1h ), 3 . 85 ( m , 1h ), 2 . 80 ( m , 2h ), 2 . 67 ( m , 1h ), 2 . 41 ( m , 1h ), 1 . 9 ( m , 3h ), 1 . 67 ( m , 4h ). prepared by a procedure analogous to that described ( see example 7 ) for the preparation of the endo - 6 -[( 4 - pyridyl ) methanethiomethylene ]- 8 -( tertbutyloxycarbonyl )- 8 - azabicyclo [ 3 . 2 . 1 ] octane with the exo analog and ( 4 - pyridyl ) methanethiol providing the desired product as a clear oil ( 500 mg , 53 %). 1 h nmr ( 300 mhz , cd 3 od ): δ 8 . 46 ( m , 2h ) , 7 . 43 ( m , 2h ), 4 . 14 ( m , 1h ), 3 . 96 ( m , 1h ), 3 . 77 ( s , 2h ), 2 . 38 ( m , 2h ), 2 . 18 ( m , 1h ), 1 . 91 ( m , 1h ), 1 . 59 ( m , 7h ), 1 . 44 ( d , 9h ). prepared by a procedure analogous to that described previously ( see example 21 ) preparation of endo - 6 -( 2 - pyridinethiomethylene )- 8 - h - 8 - azabicyclo [ 3 . 2 . 1 ] octane hydrochloride ) with exo - 6 -[( 4 - pyridyl ) methanethiomethylene ]- 8 -( tertbutyloxycarbonyl )- 8 - azabicyclo [ 3 . 2 . 1 ] octane as the starting material . the product dihydrochloride salt was isolated as a yellow solid ( 700 mg ). mp 140 ° c . ; 1 h nmr ( 300 mhz , cd 3 od ): δ h 8 . 82 ( d , j = 6 . 5 hz , 2h ), 8 . 16 ( d , j = 6 . 5 hz , 2h ), 4 . 12 ( s , 1h ), 4 . 02 ( m , 1h ), 3 . 65 ( m , 1h ), 2 . 70 ( m , 2h ), 2 . 52 ( m , 1h ), 2 . 27 ( dd , j = 13 , 8 , 1h ), 1 . 79 ( m , 7h ). into a three neck flask fitted with a condenser , an addition funnel , a thermometer and flushed with argon was placed the hydroxypyridine derivative of general formula xxvi ( 1 . 5 eq ), the alcohol derivative of general formula iii ( 1 . 0 eq ) triphenylphosphine ( 1 eq ) and dry tetrahydrofuran ( 1 . 2 ml / mmol ). the mixture was cooled to 0 ° c . and diethyl azodicarboxylate ( dead ) ( 1 . 0 eq ) was added dropwise . the reaction was allowed to warm to room temperature and stirred overnight . after hydrolysis the mixture was extracted three times with etoac ( 2 ml / mmole ). the organic layers were combined , washed with water and extracted with hcl ( 1 . 0 n . 3 × 50 ml ). the aqueous layers were combined , basified to ph = 11 with sodium hydroxide ( 5 n ) and extracted with etoac ( 3 × 50 ml ). the organic layers were combined , washed with naoh ( 1n , 50 ml ), brine ( 50 ml ), dried ( mgso 4 ) and concentrated under vacuum ( 15 mm hg ) to give an oil . the crude material was purified via chromatography on silica using a gradient of chloroform and methanol as eluant . the pure compound of general formula xxvii was converted to the hcl salt . 2 -( 2 - chloroethyl )- l - methylpyrrolidine ( 3 . 17 g , 24 . 54 mmol ), 2 - hydroxypyridine ( 5 . 0 g , 45 . 0 mmol ), triphenylphosphine ( 6 . 44 g , 24 . 54 mmol ), diethyl azodicarboxylate ( 3 . 86 ml , 24 . 54 mmol ) and tetrahydrofuran ( 40 ml ) were combined , producing 2 . 0 g ( 9 . 69 mmol , 40 %) of the desired compound which was converted to the hydrochloride salt . 1 h nmr ( 300 mhz , cd 3 od ) δ 7 . 98 ( d , j = 7 hz , 1h ), 7 . 54 ( t , j = 7 hz , 1h ), 6 . 81 ( t , j = 7 hz , 1h ), 6 . 67 ( d , j = 7 hz , 1h ), 4 . 26 ( m , 2h ), 3 . 4 ( m , 2h ), 3 . 05 ( m , 1h ), 2 . 78 ( s , 3h ), 2 . 28 ( m , 2h ), 1 . 7 - 2 . 01 ( m , 5h ); lrms ( ei ) m / e 207 ( m + ). 2 -( 2 - chloroethyl )- 1 - methylpyrrolidine ( 3 . 17 g , 24 . 54 mmol ), 4 - hydroxypyridine ( 3 . 5 g , 36 . 8 mmol ), triphenylphosphine ( 6 . 44 g , 24 . 54 mmol ), diethyl azodicarboxylate ( 3 . 86 ml , 24 . 54 mmol ) and tetrahydrofuran ( 40 ml ) were combined , producing 0 . 29 g ( 1 . 40 mmol , 6 %) of the desired compound which was converted to the hydrochloride salt . 1 h nmr ( 300 mhz , cd 3 od ) δ 8 . 70 ( d , j = 7 hz , 2h ), 7 . 61 ( d , j = 7 hz , 2h ), 4 . 56 ( m , 2h ), 3 . 73 ( m , 1h ), 3 . 60 ( m , 1h ), 3 . 21 ( m , 1h ), 2 . 99 ( s , 3h ), 2 . 61 ( m , 1h ), 2 . 45 ( m , 1h ), 2 . 09 - 2 . 26 ( m , 3h ), 1 . 93 ( m , 1h ); 13 c ( 75 . 5 mhz , cd 3 od ) δ 172 . 9 , 144 . 4 , 114 . 7 , 69 . 1 , 68 . 1 , 57 . 5 , 40 . 1 , 31 . 0 , 30 . 7 , 22 . 7 ; lrms ( ei ) m / e 207 ( m + ); mp 173 - 174 ° c . 3 h - nicotine binding to rat cerebral membranes can be performed according to modifications of the method of flyn and mash ( j . neurochem . 47 : 1948 ( 1986 )). for example , 3 h - nicotine ( 80 ci / mmol ; new england nuclear corporation , boston , mass .) can be used as the ligand for nicotinic acetylcholine receptor binding assays . an exemplary binding assay can be performed as follows . decapitate male sprague - dawley rats ( 250 - 400 gm ) and remove the brains and dissect the cerebral cortex on ice . synaptic membranes can be prepared by homogenizing the cortical tissue in 20 volumes of ice - cold modified tris buffer ( 50 mm tris ph 7 . 4 , 120 mm nacl , 5 mm kcl , 2 mm edta , 1 mm pmsf ) with a polytron ( 20 sec at setting 5 - 6 ) followed by centrifugation ( 15 min at 25 , 000 × g ) at 4 ° c . rehomogenize the resultant pellet and centrifuge twice . resuspend the final pellet in ice - cold assay buffer ( 50 mm tris ph 7 . 4 , 120 mm nacl , 5 mm kcl , 2 mm cacl 2 , 1 mm mgcl 2 ) at a concentration of membrane equivalent to 1 gm wet weight cortex per 10 ml buffer . after protein determination dilute the final membrane preparation with buffer to 3 mg protein / ml . this membrane preparation can be used in either the fresh state or frozen (− 70 ° c .) then thawed . the binding assay can be performed manually using 96 - well plates , or using a biomek automated work station ( beckman instrument co .) . dilute 3 h - nicotine in assay buffer to give a final concentration of 1 . 9 nm . program the biomek automated work station to automatically transfer 750 μl of assay buffer with 3 h - nicotine , 230 μl of membrane preparation and 20 μl of solution containing the compound of interest in assay buffer , dmso , ethanol : dmso ( 1 : 1 ) or appropriate vehicle to the 96 - well plate . add atropine to the incubation buffer at a final concentration of 3 μm to block binding to muscarinic acetylcholine receptor sites . maintain the plates on ice for 60 min and separate the tissue - bound radioactivity from the free by rapid filtration in a brandel harvester onto gf / c filters presoaked in 0 . 5 % polyethyleneimine for at least 2 hr . wash the filters with 4 × 2 ml of ice - cold assay buffer and transfer the filters to vials to which 4 ml of scintillation cocktail has been added . measure the radioactivity in a ls - 6500 beckman liquid scintillation counter in an auto - dpm mode . data can be analyzed by log - logit transformation or non - linear regression analysis ( e . g ., employing graphpad prism , available from graphpad software , san diego , calif .) to give ic 50 values . non - specific binding can be defined by 10 μm cytisine . measurement of 3 h - dopamine ( 3 h - da ) release from rat striatal slices can be performed according to the method of sacaan et al ., ( j . pharmacol . comp . ther 224 : 224 - 230 ( 1995 )). for example , the striata or olfactory tubercles can be dissected from male sprague - dawley rats ( 250 - 300 g ) quickly on a cold glass surface . chop the tissue to a thickness of 300 μm with a mcilwain tissue chopper . after chopping again at right angles disperse the tissue and incubate for 10 min . at 37 ° c . in oxygenated kreb &# 39 ; s buffer . 3 h - dopamine ( 40 ci / mmol , nen - dupont , boston , mass .) can be added ( 50 nm ) and the tissue incubated for 30 min . in kreb &# 39 ; s buffer containing 10 μm pargyline and 0 . 5 mm ascorbic acid . transfer aliquots of the minced tissue to chambers of a brandel superfusion system and support the tissue on whatman gf / b filter discs . superfuse the tissue with buffer at a constant flow rate of 0 . 3 ml / min by means of a brandel peristaltic pump . collect the perfusate in plastic scintillation vials in 3 - min fractions , and estimate the radioactivity by scintillation spectrophotometry . discard the superfusate for the first 120 min . collect two baseline fractions then switch the superfusion buffer to fresh buffer with or without compound of interest . at the end of the experiment remove the filter and the tissue and estimate the radiolabeled neurotransmitter content after extraction into scintillation fluid . the fractional efflux of radiolabeled neurotransmitter is estimated as the amount of radioactivity in the perfusate fraction relative to the total amount in the tissue . functional assays for acetylcholine receptors are described in u . s . pat . no . 5 , 369 , 028 , issued nov . 29 , 1994 ( also published as wo91 / 15602 ), as well as published pct application nos . wo94 / 20617 ( see especially example 4 . 3a ) and wo96 / 41876 ( see especially example 6e , the disclosures of which are hereby incorporated by reference herein . the results of functional assays as per the above - referenced publications with several invention compounds are summarized in table i . it can readily be seen from inspection of the data in the table that a wide variety of compounds which fall within the scope of the present invention are effective modulators of calcium flux . while the invention has been described in detail with reference to certain preferred embodiments thereof , it will be understood that modifications and variations are within the spirit and scope of that which is described and claimed .
in accordance with the present invention , a novel class of substituted pyridine compounds that promote the release of ligands involved in neurotransmission have been discovered . in a particular aspect compounds of the present invention are capable of modulating acetylcholine receptors . the compounds of the present invention are capable of modulating acetylcholine receptors . invention compounds may act as agonists , partial agonists , antagonists or allosteric modulators of acetylcholine receptors . therapeutic indications for compounds with activity at acetylcholine receptors include diseases of the central nervous system such as alzheimer &# 39 ; s disease and other diseases involving memory loss and / or dementia ; cognitive dysfunction , disorders of extrapyramidal motor function such as parkinson &# 39 ; s disease , progressive supramuscular palsy , huntington &# 39 ; s disease , gilles de la tourette syndrome and tardive dyskinesia ; mood and emotional disorders such as depression , anxiety and psychosis ; substance abuse including withdrawal symptoms and substitution therapy ; neurocrine disorders and dysregulation of food intake , including bulimia and anorexia ; disorders or nociception and control of pain ; autonomic disorders including dysfunction of gastrointestinal motility and function such as inflammatory bowel disease , irritable bowel syndrome , diarrhea , constipation , gastric acid secretion and ulcers ; pheochromocytoma , cardiovascular dysfunction including hypertension and cardiac arrhythmias , as well as co - medication uses in surgical applications .