Enantioselective Intermolecular C-H Functionalization of Primary Benzylic C-H Bonds Using ((Aryl)(diazo)methyl)phosphonates.

Catalyst-controlled C-H functionalization using donor/acceptor carbenes has been shown to be an efficient process capable of high levels of site control and stereocontrol. This study demonstrated that the scope of the donor/acceptor carbene C-H functionalization can be extended to systems where the acceptor group is a phosphonate. When using the optimized dirhodium catalyst, Rh ₂ ( S-di -(4-Br)TPPTTL) ₄ , ((aryl)(diazo)methyl)phosphonates undergo highly enantioselective (84-99% ee) and site-selective (>30:1 r.r.) benzylic C-H functionalization. The phosphonate group is much more sterically demanding than the previously studied carboxylate ester group, leading to much higher selectivity for a primary site versus more sterically crowded positions. The effectiveness of this methodology has been demonstrated by the late-stage primary C-H functionalization of estrone, adapalene, ( S )-naproxen, clofibrate, and gemfibrozil derivatives.
Competing Interests: The authors declare the following competing financial interest(s): H.M.L.D. is a named inventor on a patent entitled, Dirhodium Catalyst Compositions and Synthetic Processes Related Thereto (US 8,974,428, issued March 10, 2015). The other authors have no competing financial interests.
(© 2023 The Authors. Published by American Chemical Society.)