Rhodium-Catalyzed Asymmetric Hydroselenation of 1-Alkynylindoles for Atroposelective Synthesis of Vinyl Selenoethers

Catalytic asymmetric hydrofunctionalization of pi-bonds has been extensively studied, but the asymmetric hydrofunctionalization of alkynes that affords atropoisometric products remains heavily underexplored. We herein report [Rh(COD)OAc]2/Mg(NTf2)2-catayzed highly atroposelective hydroselenation of two classes of 1-alkynylindoles using selenophenols, where the Mg(II) salt both activates the Rh catalyst and provides a key NTf2 anion essential for the catalytic activity and enantioselectivity, affording C-N axially chiral trisubstituted olefins that bear a relatively low racemization barrier (Delta G double dagger similar to 27 kcal/mol). The catalytic system features high activity, mild reaction conditions, good functional group tolerance, and high regio-, (E)-, and enantioselectivity. The selenoether moiety in the product framework can be readily functionalized to give synthetically useful products.