Conversion of Iodocyclopropanes into Cyclopropylzinc Chlordes and Pd(0)-Catalyzed Cross-Coupling of the Latter Derivatives with Alkenyl Iodides and Iodobenzene: Stereospecific Syntheses of 1,2-Bisalkenylcyclopropanes and 1-Alkenyl-2-phenylcyclopropanes

摘要

A method for the preparation of functionalized cyclopropylzinc chlorides,which involves treatment of substituted 2-alkenyl-1-iodocyclopropanes with BuLi followed by transmetalation of the resultant cyclopropyllithium with zinc chloride,is described.Palladium(0)-catalyzed cross-coupling of the cyclopropylzinc chloride derivatives with alkenyl iodides or iodobenzene provides highly substituted 1,2-bisalkenylcyclopropanes or 1-alkenyl-2-phenylcyclopropanes.In two of the cases studied,the initially formed cis-1,2-bisalkenylcyclopropanes 27,29 underwent partial Cope rearrangement under the cross-coupling conditions to afford the corresponding 1,4-cycloheptadienes 28 and 30,respectively.