Silylated pyrrolidones via diastereoselective Pd-catalysed intramolecular allylic alkylations

A new palladium-catalysed allylic alkylation affording silylated 3-vinyl-py rrolidones has been developed. The method relies upon the interaction betwe en a stabilised acetamide enolate anion and a silicon-containing nitrogen-t ethered eta (3)-allyl-palladium moiety. Two variants have been studied, inv olving location of the silicon atom on either olefinic carbon atom of the c yclisation precursor. In both cases 5-exo-trig ring closure was the only cy clisation process observed. These results contrast with related beta -ketoe ster cyclisations, were competitive 7-endo-trig is observed. (C) 2001 Elsev ier Science Ltd. All rights reserved.