Nucleophilic Conjugate 1,5-Addition of Gilman Reagents to (E)-Hex-2-en-4-ynedioates: An Access to β(γ')-Substituted Muconates

An unusual nucleophilic conjugate addition of organocuprates to enynedioates resulted in chemo- and regioselective formation of β( γ')-addition products, rather than α(δ')-addition products, in moderate to good yields. This addition pattern is different from that with organophosphanes or alkyl amines, and presents a short and efficient method for the preparation of various β(γ')-alkyl- or -aryl-substituted muconates compared with other synthetic approaches.