Iridium-catalyzed, intermolecular hydroamination of unactivated alkenes with indoles
Christo S Sevov1, Jianrong Steve Zhou, John F Hartwig
1Division of Chemical Sciences, Lawrence Berkeley National Laboratory, Department of Chemistry, University of California , Berkeley, California 94720.
Abstract:
The addition of an N-H bond to an olefin is the most direct route for the synthesis of alkylamines. Currently, intermolecular hydroamination is limited to reactions of a narrow range of reagents containing N-H bonds or activated alkenes, and all the examples of additions to unactivated alkenes require large excesses of alkene. We report intermolecular hydroamination reactions of indoles with unactivated olefins. The reactions occur with as few as 1.5 equiv of olefin to form N-alkylindoles exclusively and in good yield. Characterizations of the catalyst resting state, kinetic data, labeling studies, and computational data imply that the addition occurs by olefin insertion into the Ir-N bond of an N-indolyl complex and that this insertion reaction is faster than insertion of olefin into the Ir-C bond of the isomeric C-2-indolyl complex.
More Related Videos
Related Concept Videos
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:36Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
03:08Hydroboration-Oxidation of Alkenes
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
02:40Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.