Metallated enamines have been used to prepare a number of morphine-based analgesics, including efficient entry to the 4a-phenylisoquinolines and morphinans. Stereocontrolled formation of both cis and trans-fused perhydroisoquinolines has been accomplished by either kinetic or thermodynamic protonation of the corresponding octahydroisoquinoline. Reaction of 4a-phenyloctahydroisoquinolinium perchlorates with diazomethane afforded the expected aziridinium perchlorate with a component of direct cyclization to the morphinan structure also observed. Kornbloom oxidation to the α-amino-aldehyde was accomplished on treatment of the aziridinium salts with dimethyl-sulfoxide. The aldehydes were cyclized to the morphinan structure on reaction with boron trifluoride etherate, providing ready access to intermediates used by Gates in his pioneering total synthesis of morphine.</p
