STEREOCHEMICAL STUDIES, 145. SATURATED HETEROCYCLES, 152. PREPARATION AND CONFORMATIONAL ANALYSIS OF STEREOISOMERIC 1,6,7,11b-TETRAHYDRO-2HOXAZINOISOQUINOLIN-4-ONE DERIVATIVES

Article abstract of DOI:10.1016/S0040-4020(01)90539-3

Starting from 1--6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline 3a, trifunctional 1,2,3,4-tetrahydroisoquinolines were synthetized.From the N-ethoxycarbonyl derivative of 3a, (r-11b,c-1)-1-hydroxymethyl- (8) and (r-11b,t-1)-1-chloromethyl-9,10-dimethoxy-1,6,7,11b-tetrahydro-2H<1,3>oxazino<4,3-a>isoquinolin-4-one (9) were formed in unexpected reactions.High-resolution NMR revealed that the tetrahydroisoquinoline-fused C-1 epimer oxazinone derivatives 8 and 9 have different conformations in solution.The first X-ray diffraction evidence of the presence of two different conformations of oxazinoisoquinolines 8 and 9 in the solid state is provided.