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 carbeneinduced 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 Rh 2 (S-2-Cl-5-BrTPCP) 4 as catalyst, whereas Rh 2 (S-TPPTTL) 4 was the most effective catalyst for C−H functionalization at tertiary C−H bonds and for the desymmetrization of N-phthalimidocyclohexane.

Catalytic alkane C–H functionalization by carbene insertion into unactivated C(sp3)–H bonds

“…Site-selectivity resulting from different metal catalysts is summarized for acyclic alkanes with various C–H bonds. Notably, many elegant works on C(sp 3 )–H insertion with substrates containing activating groups (aryl, alkenyl or heteroatoms) 34 or directing groups 35 are not covered.…”