Stereoselective synthesis of new beta-lactams by cyclocondensation of 1-methoxy-3-(trimethylsilyloxy)-1,3-butadiene with 4-formyl substituted azetidinones

The BF3. OEt2 or LiClO4 catalyzed hetero Diels-Alder reaction of 1-methoxy-3-(trimethylsilyloxy)-1,3-butadiene (Danishefsky's diene) with enantiomerically pure 4-formylazetidin-2-ones affords the corresponding cycloadducts in fair to good yields and in diastereoisomeric ratios of up to 98:2. (C) 1998 Elsevier Science S.A. All rights reserved.