Some novel reactions of pyridinium-2-carboxylate betaines

Abstract

Appropriate 2-ethoxycarbonylpyridinium salts are hydrolysed to 1 -aryl-4,6-diphenylpyridinium-2-carboxylate betaines which undergo thermal decarboxylation to afford, in the presence acids, 1 -aryl-2,4-diphenylpyridinium salts. The intermediate ylides are captured by acid chlorides to yield 2-acylpyridinium salts and by CS₂, to give dithio analogues of the starting betaines. With bromine, the carboxylate betaine yields a 2,2′-bipyridyl bisquaternary salt.

1-Benzyl-4,6-diphenylpyridinium-2-carboxylate with benzoyl chloride yields 2-benzoyl-4,6-diphenyrlpyridine and benzyl chloride. Benzaldehydes in place of PhCOCl, also gave 2-acylpyridines.