Synthesis and Reactivity of Trifluoromethylthiophosphonium Salts^†

Abstract

Comprehensive SummaryThis article described an unprecedented synthesis of trifluoromethylthiophosphonium salts from allyl trifluoromethyl sulfoxide and phosphines in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) through Mislow‐Evans‐type rearrangement. The resulting trifluoromethylthiophosphonium salts were firstly isolated and fully characterized. These fluoroalkylphosphonium salts, as exemplified by trifluoromethylthio triphenylphosphonium salt (6a), exhibited unique and versatile reaction with nucleophiles and deoxygenative trifluoromethylthiolation reaction of carboxylic acids. Furthermore, the photoredox catalytic tunable radical hydrotrifluoromethylation and hydrotrifluoromethythiolation of unactivated alkenes with 6a was successfully developed.

Umpolung trifluoromethylthiolation of alcohols

“…As we suspected, the use of Lewis acid decreased the yield for alcohols (see ESI, Table S1,† entry 9) as well as water. The proposed trifluoromethylthiophosphonium intermediate, which was recently isolated and fully characterized by Qing's group, 14 is of prime importance. To our delight, the target product ( 2a ) was isolated in 85% yield under the optimized reaction conditions (Table 1, entry 1).…”