Selenocyclisations of homoallylic sulfonamides: stereoselective methods for the elaboration of substituted pyrrolidines, pyrrolines and derivatives

摘要

Selenocyclisations of the homoallylic sulfonamides [e.g., 26,28 and 30] using phenylselanyl halides lead exclusively to beta-selanyl-pyrrolidines [e.g., 27,29 and 31] by an overall 5-endo-trig pathway, but with considerable variations in the stereochemical outcome, depending upon the substituents and the precise conditions used. Subsequent oxidative eliminations lead smoothly to the corresponding 3-pyrrolines and thence to poly-hydroxylated pyrrolidines. (c) 2006 Published by Elsevier Ltd.