Copper(I)-Catalyzed Addition of Grignard Reagents to in Situ-Derived N-Sulfonyl Azoalkenes: An Umpolung Alkylation Procedure Applicable to the Formation of Up to Three Contiguous Quaternary Centers

摘要

Ketone α-alkylation is fundamental to organic synthesis. Notwithstanding the structural limitations of the electrophile, it is most often achieved by the addition of an alkyl halide to a preformed enolate/azaenolate (Scheme la). Transition metals have been investigated recently for catalytic ketone a-alkylation using a variety of enolate species or precursors.