Regio- and stereoselectivity of the reactions of pyridinium and picolinium salts and ylids with nitriles containing a nucleofugic group

The reaction of pyridinium, 2-picolinium, and 3-picolinium ylids with tetracyanoethylene, ethoxymethylenemalononitrile, and (dimethylthio)methyl-enecyanamide in the presence of organic bases proceeds regio- and stereo-selectively to give substituted pyridinium 1,4-ylids, 2-(2-propen-1-ylidene)-1,2-dihydropyridines, and 5-(1-pyridino)pyrimidin-4-olates, respectively. The reaction of 1-phenacylpyridinium bromide and tetracyanoethylene leads to 1-phenacylpyridinium tricyanoethenolate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 939–942 April, 1990.