(−)-N-[(Cyclopropyl) methyl]-3,4-dimethoxy-5-methylmorphinan-6-one,an opioid agonist with preference for kappa opioid receptors

N-Allyl- and N-(Cyclopropyl)methyl]-3,4-dimethoxy-5-methylmorphinan-6-one ( 9 and 10, resp.) were synthesized from 5-methyldih drothebainone ( 1 ). This essential intermediate was prepared from the baine via 5-methylthebaine (5) employing a novel route. The Pharmacological studies showed 9 and 10 to be potent opioid agonists. Compound 10 was found to have preference for kappa rather than mu opioid receptors.