Palladium-catalysed vinylic substitution of aryl/vinyl iodides and triflates with alpha-methylene-gamma-butyrolactone - An application to the synthesis of 3-alkyl-gamma-butyrolactones through combined palladium-catalysed coupling/hydrogenation reactions

The palladium-catalysed arylation/vinylation of alpha -methylene-gamma -but yrolactone (1) proceeds in good yield, mainly to give stereodefined aryl/vi nyl-substituted alpha -alkylidene-gamma -butyrolactones 4. In addition, the palladium-catalysed arylation of alpha -methylene-gamma -butyrolactone (1) may be directed towards the synthesis of 3-benzylfuran-2(5H)-ones 3 when t he starting aryl iodides contain groups with electron-withdrawing conjugati ve properties. The combined palladium-catalysed coupling/hydrogenation reac tions represent a new, simple route to functionalised 3-alkyl-gamma -butyro lactones 5, giving prominence to the possibility of stereocontrol in the fo rmation of the new stereocentres.