Diastereoselectivity in the alkylations of bicyclic piperidinones

The synthesis of substituted [4.3.0] bicyclic lactams derived from 6-oxo-2-hydroxymethylpiperidine is described. The enolate derived from these systems can be alkylated with a range of reactive electrophiles; the diastereoselectivity which can be achieved depends on the substitution pattern of the oxazolidine ring system and the nature of the alkylating reagent, and can vary from 1:1 to as much as 10:1. (C) 1998 Elsevier Science Ltd. All rights reserved.