Electrophilic substitutions of 1-alkenylcyclopropyl esters: Diethylzinc-mediated umpolung of pi-1,1-dimethyleneallyl palladium complexes

1-Ethenylcydopropyl sulfonates underwent regioselective electrophilic gamma -substitution by carbonyl compounds in the presence of palladium(0) (5%) an d of diethylzine (2 equiv), to provide 3-cyclopropylidenepropan-1-ol deriva tives in high yields (74-85%); however, the alpha-substitution which led to 1-ethenylcyclopropylcarbinol derivatives was governed by the trialkylsilyl substituent effect.