Creation of quaternary stereocenters by the addition of allyltributyltin to chiral cyclic N-acyliminium ions

5,5-Disubstituted pyrrolidinones and 5-substituted pyrrolidinones were obta ined with moderate to good diastereoisomeric excess through the cis additio n of allyltributyltin and triethylsilane, respectively, to the 4-OTBS group in the N-acyliminium ion prepared from the corresponding 5-hydroxy lactams . Cyclization of an N-allyl-5-propargyl pyrrolidinone and N-allyl-5-allyl-5 -substituted pyrrolidinones using Grubbs' catalyst led to the preparation o f a dehydropyrre lizinone and dehydroindolizinones containing a quaternary stereocenter. (C) 2000 Elsevier Science Ltd. All rights reserved.