Ti-Catalyzed Ring-Opening Oxidative Amination Of Methylenecyclopropanes With Diazenes

The ring-opening oxidative amination of methylenecyclopropanes (MCPs) with diazenes catalyzed by py(3)TiCl(2)(NR) complexes is reported. This reaction selectively generates branched alpha-methylene imines as opposed to linear alpha,beta-unsaturated imines, which are difficult to accessviaother methods. Products can be isolated as the imine or hydrolyzed to the corresponding ketone in good yields. Mechanistic investigationviadensity functional theory suggests that the regioselectivity of these products results from a Curtin-Hammett kinetic scenario, where reversible beta-carbon elimination of a spirocyclic [2 + 2] azatitanacyclobutene intermediate is followed by selectivity-determining beta-hydrogen elimination of the resulting metallacycle. Further functionalizations of these branched alpha-methylene imine products are explored, demonstrating their utility as building blocks.