New utility of electrophilic trifluoromethylthiolation reagents for the synthesis of a variety of triflones

Abstract

The synthesis of various triflones has been achieved using electrophilic trifluoromethylthiolation reagents as building blocks, and not as reagents. Trifluoromethanesulfonyl hypervalent iodonium ylide 1a and its diazo-analogue 1b are well-known reagents for electrophilic trifluoromethylthiolation of nucleophiles under copper catalysis. In this paper, we disclose another facet of these reagents as synthetic building blocks of triflones via intramolecular rearrangements. The diazo-compound 1b was converted into amide-, ester- and enol-triflones via the Wolff rearrangement followed by a nucleophilic reaction with aryl- and alkylamines, amino acids, alcohols, and silyl enol ether in heated conditions. On the other hand, the ylide reagent 1a was converted into vinyl triflone via an intramolecular I-O-rearrangement under heat. More interestingly, both 1a and 1b reacted with acetonitrile to give an oxazole-triflone under copper catalysis.