N-Phthalimide as a Site-Protecting and Stereodirecting Group in Rhodium-Catalyzed C-H Functionalization with Donor/Acceptor Carbenes

Abstract

The rhodium-catalyzed enantioselective C-H functionalization of unactivated C-H bonds by means of donor/acceptor carbene-induced C-H insertion was extended to substrates containing nitrogen functionality. The rhodium-stabilized donor/acceptor carbenes were generated by rhodium-catalyzed decomposition of aryldiazoacetates. The phthalimido group was the optimum nitrogen protecting group. C-H functionalization at the most sterically accessible methylene site was achieved using Rh2(S-2-Cl-5-BrTPCP)4as catalyst, whereas Rh2(S-TPPTTL)4was the most effective catalyst for C-H functionalization at tertiary C-H bonds and for the desymmetrization of N-phthalimidocyclohexane.