α-Olefins as Alkenylmetal Equivalents in Catalytic Conjugate Addition Reactions

摘要

First documented over a century ago, conjugate additions are among the most utilized organic reactions. In carbon-carbon bond-forming variants, the nucleophile is typically organo-metallic. Earlier technology employed enolate, organo-lithium, Grignard, or organocopper reagents; more recently, organozinc and organoboron compounds have enhanced this transformation significantly. Despite increased functional group tolerance, an organometallic or an organometalloid compound is nonetheless required in these powerful methods. Herein we describe a novel conjugate addition reaction in which a simple, unactivated alkene (ethylene, an α-olefin, or styrene) takes the place of the organometal reagent [Eq. (1)]. Thus, although an alkene is not an alkenylmetal reagent per se, it functions as one in this carbon-carbon bond-forming process.