Construction of Quaternary Stereogenic Carbon Centers through Copper-Catalyzed Enantioselective Allylic Cross-Coupling with Alkylboranes

A combination of an in situ generated chiral CuI/DTBM‐MeO‐BIPHEP catalyst system and EtOK enabled the enantioselective SN2′‐type allylic cross‐coupling between alkylborane reagents and γ,γ‐disubstituted primary allyl chlorides with enantiocontrol at a useful level. The reaction generates a stereogenic quaternary carbon center having three sp3‐alkyl groups and a vinyl group. This protocol allowed the use of terminal alkenes as nucleophile precursors, thus representing a formal reductive allylic cross‐coupling of terminal alkenes. A reaction pathway involving addition/elimination of a neutral alkylcopper(I) species with the allyl chloride substrate is proposed. The SN2′‐type: A combination of a chiral CuI/L* catalyst system and EtOK enabled the enantioselective SN2′‐type allylic cross‐coupling between alkylboranes and γ,γ‐disubstituted primary allyl chlorides. The reaction generates quaternary carbon stereogenic centers bearing three sp3‐alkyl groups and a vinyl group. A reaction pathway involving addition/elimination of a neutral alkylcopper(I) species is proposed.