New Umemoto’s Reagent II for Trifluoromethylation

The trifluoromethyl group has unique properties such as high electronegativity, metabolic stability and lipophilicity. The installment of a trifluoromethyl group is one of the significant functionalizations and is utilized for development in various fields, like pharmaceuticals, agricultural chemicals and material science. S-(Perfluoroalkyl)dibenzothiophenium salt 1, which has been developed by Umemoto et al., is useful as an electrophilic trifluoromethylating reagent. 1 is applicable for many reactions under basic conditions such as trifluoromethylation of β-ketoesters at the α-position, direct trifluoromethylation of indoles at the 2-position, and hydroxytrifluoromethylation of styrene derivatives using photoredox catalysts.¹⁾