Rhodium(III)-catalyzed Oxidative Coupling of N-Methoxybenzamides and Ethenesulfonyl fluoride: a C–H Bond Activation Strategy for the Preparation of 2-Aryl ethenesulfonyl fluorides and Sulfonyl fluoride Substituted γ-Lactams

A method for the synthesis of 2-aryl ethenesulfonyl fluorides and sulfonyl fluoride substituted γ-lactams was developed through a rhodium(III)-catalyzed oxidative coupling of N-methoxybenzamides and ethenesulfonyl fluoride (ESF) in moderate to excellent yields. This protocol featured an exclusive E-stereo selectivity and a monoselective ortho activation of sp2 C–H bonds of the phenyl rings. This research revealed that the much less reactive Heck coupling partner ethenesulfonyl fluoride (ESF) possesses the feasibility for coupling with sp2 C–H bonds to provide a class of new sulfonyl fluoride scaffolds for the SuFEx click reaction.