Effect of Multinuclear Copper/Aluminum Complexes in Highly Asymmetric Conjugate Addition of Trimethylaluminum to Acyclic Enones

摘要

Over the past few decades, the asymmetric conjugate addition of organometallic reagents to activated olefins has become one of the most powerful approaches to chiral molecules, especially for installation of a small alkyl group on a chiral carbon atom. Although there have been various reports on the asymmetric conjugate addition of organometallic reagents to cyclic enones for the creation of an all-carbon substituted chiral quaternary stereogenic center, the use of acyclic enones still presents a formidable challenge. The steric congestion around a β,β-disubstituted olefin prevents 1,4-addition, but favors 1,2-addition, and the chiral catalyst hardly recognizes the enantioface because of the similarity of substituents on an olefinic carbon atom (Figure 1).