Asymmetric Vicinal and Remote Hydroamination of Olefins by Employing a Heck-Reaction-Derived Hydride Source

Metal hydrides are reactive intermediates in numerous catalytic processes. In many catalytic processes, metal hydrides are formed, but their potential reactivity is often wasted by reaction with a base or an oxidant to permit catalyst turnover. In this report, the hydroamination of unactivated olefins is described by coupling a Heck reaction with a hydroamination reaction between aryl boronic acid, olefin, and a nitrene precursor dioxazolone. Initiated by a Heck reaction between the olefin and arylboroic acid, a rhodium hydride intermediate is generated and is retained for the hydroamination of a second equivalent of the olefin. Depending on the chain length of the alkyl group of the olefin, α- or β-amino amides were obtained in excellent regio- and enantioselectivity via direct or remote (migratory) hydroamination, respectively. The coupling system features a broad scope, mild conditions, and excellent enantioselectivity, and it also represents a rare example of asymmetric olefin hydroamination using a chiral rhodium(III) cyclopentadienyl catalyst. Mechanistic studies delineated the turnover-limiting and enantio-determining steps of this catalytic system.