NEW N-SUBSTITUTED AMMONIUM SALTS OF (2-ETHOXY-2-OXOETHYL)ARYL-PHOSPHINIC ACIDS
Earlier, we obtained the ammonium salts of phosphoryl acetic acids by the reaction of phenyl and (4-chlorophenyl) phosphinic acids with glycine and α-alanine esters. Studying the neurotropic activity of these salts showed the presence of psychotropic activity in various behavioral models, including affecting learning processes and memory, as well as antidepressant and anxiolytic properties. To extend the series of the salts of phosphoryl acetic acids, containing an amino acid fragment, and to study the effect of the substituent in the aromatic ring on neurotropic activity, new representatives of phosphoryl-carboxylic acids have been synthesized: (2-ethoxy-2-oxoethyl) aryl-phosphinic acids containing methyl or methoxy group in the para position of the aromatic nucleus. As the initial reagent, the relevant aryl-dichloro-phosphines were used, the hydrolysis of which led to forming aryl-phosphinic acids. The latter ones were introduced into the reaction with ethyl bromoacetate through the stage of forming di(trimethylsilyl) esters, and (2-ethoxy-2-oxoethyl) aryl-phosphinic acids were isolated after deprotecting the silyl groups. The acids synthesized reacted with amino acid esters and yielded the crystalline N-substituted ammonium salts of (2-ethoxy-2-oxoethyl) aryl-phosphinic acids. Glycine ethyl ester and L-α-alanine methyl ester acted as the cationic component of the salts, and (2-ethoxy-2-oxoethyl) 4-methyl and 4-methoxyphenylphosphinic acids acted as the anionic component. Free amino acid esters were isolated from the corresponding hydrochlorides using ammonia as an acceptor of hydrogen chloride. Structures of all isolated compounds were studied using 1H, 31P NMR and IR spectroscopy, the composition was confirmed by elemental analysis.