Michael–Michael Ring-Closure Reactions for a Dihapto-Coordinated Naphthalene Complex of Molybdenum

The complex MoTp­(NO)­(DMAP)­(η2-naphthalene) (1; DMAP = 4-(dimethylamino)­pyridine; Tp = tris­(pyrazolyl)­borate) is demonstrated to undergo Michael–Michael ring-closure (MIMIRC) reactions promoted by trimethylsilyltriflate. The resulting hexahydrophenanthrenes are formed stereoselectively, with isolation of a single dominant isomer. Combining the MIMIRC sequence with an oxidative decomplexation step, the final tricyclics can be synthesized from the naphthalene complex with overall yields between 19 and 50% (for four steps). This reaction sequence is shown to be capable of producing a steroidal core directly from naphthalene, providing access to a biologically relevant carbon framework.