SYNTHESIS OF 3-SUBSTITUTED TETRAHYDROISOQUINOLINES BY ACID-CATALYZED CYCLIZATION OF P-TOLUENESULFONAMIDES OF N-BENZYL AMINOACETALDEHYDE DERIVATIVES

The acid-catalyzed cyclization of p-toluenesulfonamides of N-benzyl am inoacetaldehyde, or their acetalic counterparts, usually yields 1,2-di hydroisoquinolines. However, cyclization of intermediates bearing a su bstituent or to the carbonyl group affords 3-substituted 2-p-toluenesu lfonyl tetrahydroisoquinolin-4-ol derivatives, capable of further tran sformation into the related 1,2,3,4-tetrahydroisoquinolines.