Rhodium-Catalyzed Alkene Difunctionalization with Nitrenes

The Rh-II-catalyzed oxyamination and diamination of alkenes generate 1,2-amino alcohols and 1,2-diamines, respectively, in good to excellent yields and with complete regiocontrol. In the case of diamination, the intramolecular reaction provides an efficient method for the preparation of pyrrolidines, and the intermolecular reaction produces vicinal amines with orthogonal protecting groups. These alkene difunctionalizations proceed by aziridination followed by nucleophilic ring opening induced by an Rh-bound nitrene generated in situ, details of which were uncovered by both experimental and theoretical studies. In particular, DFT calculations show that the nitrogen atom of the putative [Rh](2)=NR metallanitrene intermediate is electrophilic and support an aziridine activation pathway by N center dot center dot center dot N=[Rh](2) bond formation, in addition to the N center dot center dot center dot[Rh](2)=NR coordination mode.