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

The synthesis of various triflones has been achieved using electrophilic trifluoromethylthiolation reagents as building blocks, and not as reagents. Trifluoromethanesulfonyl hypervalent iodonium ylide la and its diazo-analogue lb 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 lb 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 la was converted into vinyl triflone via an intramolecular 1-0-rearrangement under heat. More interestingly, both la and lb reacted with acetonitrile to give an oxazole-triflone under copper catalysis. (C) 2016 Elsevier B.V. All rights reserved.