Asymmetric Vicinal and Remote Hydroamination of Olefins via Rhodium Hydride Relay Catalysis: Powering Olefin as an Endogenous Hydride Donor

Metal hydrides are reactive intermediates in numerous catalytic processes. In numerous 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, hydride relay catalysis based on an endogenous hydride source is described for hydroamination of unactivated olefins 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 hydroamination of a second olefin. Depending on the chain length of the alkyl group of the olefin, - or -amino amides were obtained in excellent regio- and enantioselectivity via direct and remote (migratory) hydroamination, respectively. The coupling system features 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 the enantiodetermining steps of this catalytic system.