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 gamma-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 sp(2) 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 sp(2) C-H bonds to provide a class of new sulfonyl fluoride scaffolds for the SuFEx click reaction.