All-Carbon Quaternary Stereogenic Centers by Enantioselective Cu-Catalyzed Conjugate Additions Promoted by a Chiral N-Heterocyclic Carbene


  • We are grateful to the NIH (GM-47480) and the NSF (CHE-0213009) for financial support. We thank Professor A. Alexakis (University of Geneva) for generously sharing unpublished results with us (reference [10]). M.K.B. and C.A.B. are recipients of an ACS Graduate Fellowship in Organic Chemistry (sponsored by Schering-Plough) and a Fulbright Distinguished Scholarship, respectively. The X-ray facility at Boston College is supported by Schering-Plough; Dr. R. J. Staples provided valuable assistance in obtaining X-ray structures.


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Necessity is the mother of invention: When the available catalysts do not cut it, a new one has to be developed. A chiral N-heterocyclic carbene (NHC) is used in the first catalytic asymmetric conjugate addition of alkyl- and arylzinc reagents to γ-keto esters (see scheme).