The preparation and the cascade reactions of N-butadienyl-N-alkylketene N,O-tert-butyldimethylsilyl acetals

The preparation of N-butadienyl-N-alkylketene N,O-tert-butyldimethylsilyl acetals (11a-d) from readily available starting materials is described. The cascade Diels-Alder reaction followed by acylation of these ketene acetals yields bicyclic and tricyclic products 7, 13a,b and 14c,d with high diastereoselectivity. Copyright (C) 1996 Elsevier Science Ltd