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

The complex MoTp(NO)(D )(eta(2)-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.