Efficient Preparation of Useful 1,2-Substituted Electron-Deficient Dienes from Sulpholenes and Their Use in Intramolecular Diels-Alder Reactions: A General Approach to Alkaloids

Abstract

A short, efficient sequence is described for the conversion of 3-methoxycarbonyl-3-sulpholene [3-methoxycarbonyl-2,5-dihydrothiophene 1,1-dioxide (3)] into 2,3-disubstituted diene precursors bearing an ester or amide at the 3-position. The trans-1,2,3,4,4a,7,8,8a-octahydroisoquinolines 12 and 13 are prepared selectively from the sulpholenes via intramolecular exo Diels-Alder reactions.