Nickel-Catalyzed Enantioconvergent and Diastereoselective Allenylation of Alkyl Electrophiles: Simultaneous Control of Central and Axial Chirality

Abstract

In recent years, remarkable progress has been described in the development of methods that simultaneously control vicinal stereochemistry, wherein both stereochemical elements are central chirality; in contrast, methods that control central and axial chirality are comparatively rare. Herein we report that a chiral nickel catalyst achieves the enantioconvergent and diastereoselective coupling of racemic secondary alkyl electrophiles with prochiral 1,3-enynes (in the presence of a hydrosilane) to generate chiral tetrasubstituted allenes that bear an adjacent stereogenic center. A carbon–carbon and a carbon–hydrogen bond are formed in this process, which provides good stereoselectivity and is compatible with an array of functional groups.

Silanes as a versatile hydride source for Ni–H catalysis: a promising tool for π-hydro functionalization

“…The intermediate ( 72 ) then coupled with the racemic alkyl halide via oxidative radical addition to furnish the desired allene, which contained a stereo-genic axis and a centre (Scheme 62). 97…”