King of the ring: S‐(trifluoromethyl)benzo[b]thiophenium salts 1, as analogues of Yagupolskii–Umemoto type reagents, were synthesized by novel triflicacidcatalyzedintramolecularcyclization of ortho‐ethynylaryltrifluoromethylsulfanes 2. 1 j is especially useful for the electrophilic trifluoromethylation of β‐ketoesters and dicyanoalkylidenes.
The intra- vs intermolecular transfer-fluoromethylation of aryl fluoromethylthio compounds is proposed. Finely designed ArSCF3 (la) nicely releases its trifluoromethyl (CF3) group intermolecularly under rhodium catalysis, whereas a difluoromethylated analogue, ArSCF2H compound lb shows intramolecular reaction.
Fluorinated Johnson Reagent for Transfer-Trifluoromethylation to Carbon Nucleophiles