Reaction of Pyridinium t-Butoxycarbonylmethylide with Trifluoroacetonitrile

Article abstract of DOI:10.1016/S0022-1139(00)81234-8

Pyridinium t-butoxycarbonylmethylide (I), generated by treatment of N-(t-butoxycarbonymethyl)pyridinium perchlorate with sodium hydride in acetonitrile, reacts with trifluoroacetonitrile to give 3-(t-butoxycarbonyl)-2-(trifluoromethyl)-imidazo<1,2-a>pyridine (II), pyridinium 4,5-dihydro-4-oxo-2,6-bis(trifluoromethyl)pyrimidin-5-ylide (III), and N-<2-amino-1-(t-butoxycarbonyl)-3,3,3-trifluoroprop-1-enyl>pyridinium perchlorate (IV).Formation of the last two products, plus the fact that when treated with sodium hydride the perchlorate (IV) yields the imidazopyridine (II), provides powerful evidence in support of a stepwise mechanism for the 1,3-dipolar cycloaddition involved in formation of the imidazopyridine nucleus in (II).