PALLADIUM-CATALYZED COUPLING REACTIONS OF ARYL TRIFLATES OR HALIDES WITH KETENE TRIMETHYLSILYL ACETALS - A NEW ROUTE TO ALKYL 2-ARYLALKANOATES

Palladium complexes with phosphines, in the presence of lithium acetate, catalyze the coupling reaction of aryl triflates and ketene trimethylsilyl acetals to yield alkyl 2-arylalkanoates, 1,1'-bis(diphenylphosphino)ferrocene gives the best results. Aryl halides may also be used, provided that a stoichiometric amount of thallium acetate is present. Added acetate anions act both as palladium-bonded groups in the ArPdL2OAc reactive intermediates and as nucleophiles promoting the Si-O bond breaking of the silyl enolate moiety. The reaction represents a novel method for the preparation of alkyl 2-arylalkanoates which, after hydrolysis, afford the corresponding 2-arylalkanoic acids, well known as antiinflammatory and antipyretic drugs.