Stereoselective radical-mediated cyclization of norephedrine derived o-bromobenzamides: Enantioselective synthesis of 4-substituted 1,2,3,4-tetrahydroisoquinolines
作者:Laura Belvisi、Cesare Gennari、Giovanni Poli、Carlo Scolastico、Barbara Salom
DOI:10.1016/s0957-4166(00)82347-2
日期:1993.2
Radical-mediated cyclization of norephedrine derived o-bromobenzamide 5 was found to be fairly stereoselective (85:15)favouring diastereoisomer trans-6. Tricyclic delta-lactams 6 were transformed in high yield into enantiomerically enriched (R)-1,2,3,4-tetrahydro-2,4-dimethylisoquinoline 8. Transition state modelling with a force field developed ad hoc (see also: Belvisi, L. et al. Tetrahedron 1992, 48, 3945) nicely predicts the stereochemical results.