New approaches to 6-oxoisoaporphine and tetrahydroisoquinoline derivatives

2,3-Dihydro-6-hydroxy-5-methoxy-7H-dibenzo[de,h]quinolin-7-one, 6-hydroxy-5-methoxy-7H-dibenzo[ de,h]quinolin-7-one, and 2-(6,7-dimethoxy-3,4- dihydroisoquinolin-1-yl)benzyl benzoate, easily available by a Bischler - Napieralski cyclization, were used as starting materials to afford 6-oxoisoaporphine and 2,3-dimethoxy-5,6,8,12b-tetrahydroisoindolo[1,2-a] isoquinoline as the main products. However, the catalytic hydrogenation of the benzyl benzoate derivative afforded, under mild conditions, 1,2,3,4-tetrahydro- 6,7-dimethoxy-1-(2-methylphenyl)isoquinoline.