Regioselectivity in the reaction of azinium salts and ylides with tetracyanoethylene
摘要:
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 stereoselective 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.