Total synthesis of 8,14-dihydromorphinandienone alkaloids

A collective synthesis of 8,14-dihydronorsalutaridine, 8,14-dihydrosalutaridine, norisosinomenine, and isosinomenine is reported. The strategy provides direct access to the correct oxidation level of the products. The combination of an organocatalyst guanidine superbase, a tertiary amine base, and a dehydrating agent was necessary for the successful Henry-Michael-dehydration cascade to form the phenanthrene motif. The required selective aliphatic nitro reduction could only be achieved under heterogeneous transfer-hydrogenation conditions.