Asymmetric Allylic Alkylation Catalyzed by Palladium-Sparteine Complexes

Article abstract of DOI:10.1016/S0957-4166(00)86122-4

The cationic complex 3-C3H5)(sparteine)>PF6 (6) was found to be a suitable catalyst precursor for the asymmetric alkylation of allylic acetates with Na as the nucleophile.This constitutes one of the first and still rare examples of a phosphine-free system for this type of Pd-catalyzed reaction.Using 5 mol percent of 6, alkylation products were obtained in up to 90 percent isolated yield and 85 percent enantiomeric excess.The alkylation reaction was shown to occur with overall retention of configuration, indicating an analogous mechanism to the one previouslyproposed for phosphine-containing catalysts.The reactivity of allylic acetates is strongly dependent upon the nature of the substituents, open-chain aliphatic substrates being unreactive.