New Method for the Classification of Nucleophiles in the Palladium-Catalyzed Substitution of Allylic Acetates

Article abstract of DOI:10.1021/jo00386a004

Palladium-catalyzed reactions of nucleophiles were carried out on cyclopent-2-enyl acetate (1), 3a,4,5,6,7,7a-hexahydro-(1α,3aα,4α,7α,7aα)-4,7-methano-1H-inden-1-yl acetate (3b), and 3a,4,5,6,7,7a-hexahydro-(1β,3aα,4α,7α,7aα)-4,7-methano-1H-inden-1-yl acetate (5b) to give indications on the mechanism of the reaction and the mode of attack of the nucleophiles.The lack of reactivity of 3b confirmed that a trans relationship between the approaching Pd(O) complex and the departing acetate is required in the η³-allyl-forming step.Examination of the reactivity of the nucleophiles with 5b compared to 1 allowed a decision as to whether the primary attack of the intermediate (η³-allyl)palladium complex by the nucleophile is directed to η³-allylic ligand (Nu₁ nucleophiles: sodium dimethyl malonate, sodium cyclopentadienide, lithium thioxodiphenylphosphide, morpholide) or to the metal (Nu₂ nucleophiles: phenylzinc chloride, sodium indenide, ammonium formate).