Heterocyclic mesomeric betaines. Part 4. Reductive cyclization of derivatives of 7-methyl-2-(2′-nitrophenyl)imidazo[l,2-a]pyridine
Abstract
Reductive cyclization of derivatives of 7-methyl-2-(2′- nitrophenyl)imidazo[1,2-a]pyridine (5) with hot triethyl phosphite has been investigated and the following transformations were achieved: (5)→(15), (6)→(16), and (7)→(11). Compound (11) afforded a 2 : 1 adduct (18) when treated with dimethyl acetylenedicarboxylate.