Facile transformation of 1-methoxynaphthalenes to octahydrophenanthrenes. Application to the total synthesis of (±)-sempervirol methyl ether, (±)-sugiol methyl ether, (±)-nimbiol methyl ether, and (±)-nimbidiol dimethyl ether

Article abstract of DOI:10.1016/S0040-4039(00)76731-1

An efficient general method has been developed for the synthesis of the tricyclic aromatic ketones 4, 12, 13 and 14 from the 1-methoxynaphthalenes 8, 9, 10 and 11 respectively. The transformations of the ketones 4, 12, 13 and 14 into the diterpene ethers (±)-sempervirol methyl ether (7), (±)-sugiol methyl ether (15), (±)-nimbiol methyl ether (16), and (±)-nimbidiol dimethyl ether (17) have been successfully accomplished involving reductive methylation in liquid ammonia as the key reaction.