Rh(iii)-catalyzed regioselective intermolecular N-methylene Csp3-H bond carbenoid insertion.

A Rh(iii)-catalyzed regioselective intermolecular carbenoid insertion into the N-methylene Csp3-H bond of acyclic aliphatic amides has been achieved, taking advantage of bidentate-chelation assistance. This methodology has been successfully applied to a broad range of linear and branched-chain N-alkylamides, thus providing a practical method for the assembly of diverse beta-amino esters. Mechanism studies and density functional theory (DFT) calculations revealed that a singlet Fischer type carbene insertion via an outer-sphere pathway was involved in this N-methylene Csp3-H bond carbenoid insertion.