The ring-opening oxidative amination of methylenecyclopropanes (MCPs) with diazenes catalyzed by py3TiCl2(NR) complexes is reported. This reaction selectively generates branched α-methylene imines as opposed to linear α,β-unsaturated imines, which are difficult to access via other methods. Products can be isolated as the imine or hydrolyzed to the corresponding ketone in good yields. Mechanistic investigation via density functional theory suggests that the regioselectivity of these products results from a Curtin-Hammett kinetic scenario, where reversible β-carbon elimination of a spirocyclic [2 + 2] azatitanacyclobutene intermediate is followed by selectivity-determining β-hydrogen elimination of the resulting metallacycle. Further functionalizations of these branched α-methylene imine products are explored, demonstrating their utility as building blocks. This journal is
Bibliographical noteFunding Information:
Financial support was provided by the University of Minnesota (start-up funds, Wayland Noland Fellowship for AAO), the National Institutes of Health (1R35GM119457, 1R35GM124718) and the Alfred P. Sloan Foundation (Sloan Fellowship for IAT). NMR equipment was supported by the National Institutes of Health (S10OD011952) with matching funds from the University of Minnesota. Computational resources were provided by the Minnesota Supercomputing Institute (MSI) at the University of Minnesota and the National Energy Research Scientic Computing Center (NERSC), a DOE Office of Science User Facility supported by the U.S. Department of Energy under contract no. DE-AC02-05CH11231.