Ni-catalyzed Reductive Cross-coupling Of Aryl Halides With Unactivated Secondary And Tert-alkyl Halides And Allylic Acetates

Ni-catalyzed reductive approach to the cross-coupling of two electrophilic reagent.The mild, easy-to-handle method allows excellent functional group tolerance, andprovides cross-coupling products in moderate to excellent yields.1. A room-temperature Ni-catalyzed reductive method for the coupling of arylbromides with secondary alkyl bromides has been developed, providingC(sp~2)_C(sp~3) products in good to excellent yields. Slight modification of thisprotocol allows efficient coupling of activated aryl chlorides with cyclohexylbromide and aryl bromides with allylic acetate.2. Ni-catalyzed allylation of electron-rich aryl bromides with a variety ofsubstituted allylic carbonates using zinc as the terminal reductant, affordingE-alkenes regioselectively in good to excellent yields by the addition of arylto the less hindered allylic carbon. The electron-deficient aryl bromides andchlorides are also highly efficient coupling partners.3. A mild Ni-catalyzed reductive arylation of tertiary alkyl bromides with arylhalides has been developed, which delivers tertiary alkyl–aryl products inmoderate to excellent yields. The reaction conditions are tolerant of a widerange of functionalized unactivated alkyl halides and aryl halides withdifferent substitution patterns. The alkyl halides bearing polar substituentsand the electron-deficient aryl bromides are generally more effective.Preliminary examination suggests radical intermediates may be involved.Consequently no transmetallation step is involved in the catalytic process.