Stereoselective 1,3-dipolar cycloaddition of a nitrile ylide photochemically generated from 2,3-diphenyl-2H-azirine to substituted methylene lactones
The nitrile ylide photochemically generated from
2,3-diphenyl-2H-azirine adds to both isomers of
3-(tosyloxymethylene)tetrahydrofuran-2-one with excellent
regio- and stereoselectivity giving spiroheterocyclic products
in moderate yields. X-Ray structure determination showed
dibutolactone to have the E-configuration. The corresponding
Z-isomer was prepared photochemically.