Regioselectivity in the reaction of azinium salts and ylides with tetracyanoethylene

The reactions of pyridinium, picolinium, and quinolinium salts and ylides with tetracyanoethylene have been found to be regioselective. Reaction of azinium salts with tetracyanoethylene in aqueous methanol affords azinium tricyanoethylenolates, but pyridinium ylides react differently, with the highly stereo-selective formation of the Z-isomers of 3-aroyl-3-(R-1-pyridinio)-1,1,2-tricyano-2-propen-1-ides, which are 1,4-ylides with maximum charge separation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1431–1439, June, 1991.