Diaryldiazoketones as Effective Carbene Sources for Highly Selective Rh(II)-Catalyzed Intermolecular C-H Functionalization

A novel donor/acceptor carbene intermediate has been developed using diaryldiazoketones as carbene precursors. In the presence of the chiral dirhodium catalyst, Rh-2(S-TPPTTL)(4), diaryldiazoketones undergo highly regio-, stereo-, and diastereoselective C-H functionalization of activated and unactivated secondary and tertiary C-H bonds. Computational studies revealed that the arylketo group behaves differently than the carboxylate acceptor group because the orientation of the arylketo group predetermines which face of the carbene will be attacked.