Copper-Catalyzed Asymmetric Radical 1,2-Carboalkynylation of Alkenes with Alkyl Halides and Terminal Alkynes

A copper-catalyzed
intermolecular three-component asymmetric radical
1,2-carboalkynylation of alkenes has been developed, providing straightforward
access to diverse chiral alkynes from readily available alkyl halides
and terminal alkynes. The utilization of a cinchona alkaloid-derived
multidentate N,N,P-ligand is crucial for the efficient radical generation
from mildly oxidative precursors by copper and the effective inhibition
of the undesired Glaser coupling side reaction. The substrate scope
is broad, covering (hetero)­aryl-, alkynyl-, and aminocarbonyl-substituted
alkenes, (hetero)­aryl and alkyl as well as silyl alkynes, and tertiary
to primary alkyl radical precursors with excellent functional group
compatibility. Facile transformations of the obtained chiral alkynes
have also been demonstrated, highlighting the excellent complementarity
of this protocol to direct 1,2-dicarbofunctionalization reactions
with C­(sp2/sp3)-based reagents.