Synthesis of enantiomerically pure (-)-wine lactone based on a palladium-catalyzed enantioselective allylic substitution

The first enantioselective synthesis of enantiomerically pure (-)-wine lact one, (-)-1a, a fragrance constituent of various white wines, and its epimer (+)-1b, was carried out. The key steps are allylic substitution of (+/-)-2 -cyclohexen-1-yl acetate (2) with dimethylmalonate using palladium complexe s of phosphanyldihydrooxazol L1 or of the phosphanylcarboxylic acid L2 as c atalyst, subsequent decarboxylation, iodolactonization and elimination, fur nishing enantiomerically pure bicyclic lactone (+)-7 in 47% overall yield. The diastereoselective introduction of methyl groups by S(N)2'-type substit ution with an organocopper compound and by enolate alkylation gave lactone (-)-1a in 43% overall yield from (+)-7.