New Approaches to 6‐Oxoisoaporphine and Tetrahydroisoquinoline Derivatives

2,3‐Dihydro‐6‐hydroxy‐5‐methoxy‐7 H ‐dibenzo[ de , h ]quinolin‐7‐one, 6‐hydroxy‐5‐methoxy‐7 H ‐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.