Reactions of pyridinium t-butoxycarbonylmethylide with perfluoropropene and some fluoroaromatics

Abstract

▪ Perfluorotoluene, pentafluoropyridine, 3-chlorotetrafluoropyridine, and 3,5-dichlorotrifluoropyridine react with pyridinium t-butoxycarbonylmethylide (I) in acetonitrile at 0 – 20 °C to yield, via nucleophilic displacement of a 4-F substituent in each case, the new pyridinium methylides (II)–(V), respectively. Treatment of perfluoropropene with (I) gives 1-(t-butoxycarbonyl)-2-fluoro-3-(trifluoromethyl)- pyrrolo[1,2- a ]pyridine (VI) and 1,3-bis(t-butoxycarbonyl)-2- (1,2,2,2-tetrafluoroethyl)pyrrolo[1,2- a ]pyridine (VII), formation of the latter (minor) product providing evidence that the former arises via a stepwise dipolar cycloaddition. ▪