Iridium-Catalyzed Regiodivergent and Enantioselective Hydroalkynylation of Unactivated 1,1-Disubstituted Alkenes.

Abstract

Catalytic enantioselective functionalization of unactivated 1,1-disubstituted alkenes is challenging due to the difficulty to discriminate the enantiotopic faces. Enantioselective hydrofunctionalization of unactivated 1,1-disubstituted alkenes with tunable Markovnikov and anti-Markovnikov selectivity remains elusive. We report here an amide-directed, regiodivergent and enantioselective hydroalkynylation of unactivated alkenes. The regioselectivity can be readily tuned by the choice of a proper ligand. Catalytic alkynylations occurred with tunable Markovnikov and anti-Markovnikov selectivity to afford products containing acyclic tertiary or quaternary stereocenters β to an amide. Combining a sequence of alkene isomerization and regioselective hydroalkynylation, we further realized an iridium-catalyzed formal asymmetric conjugated alkynylation of β,β-disubstituted α,β-unsaturated amides. Computational studies suggest that the regioselectivity is dictated by the ligand structures.