Synthesis and Conformational Analysis of Stereoisomeric 1- and 2-Methyl-2H,4H-1,6,7,11b-tetrahydro-1,3-oxazinoisoquinolines

Article abstract of DOI:10.1016/S0040-4020(01)81586-6

Starting from diastereomerically pure 1-(β-hydroxyethyl)-1'-methyl- or 2'-methyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolines (3a,b and 5a,b), 4-unsubstituted, 4-p-nitrophenyl- and 4-oxo-1- or 2-methyl-9,10-dimethoxy-2H,4H-1,6,7,11b-tetrahydro-1,3-oxazino<4,3-a>isoquinoline diastereomers (a and b) 6-9, 12 and 13 were prepared.The relative configurations and the predominant conformations were determined by 1H and 13C NMR spectroscopy, use also being made of DR, DEPT, DNOE and 2D-HSC measurements.