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摘要

A potent, selective opioid receptor agonist or antagonist exhibiting properties useful for a long-acting analgesic or opiate abuse treatment agent or appetite suppressant having general formula (I), wherein R is methyl, cyclopropylmethyl or allyl, and R1 is an unsubstituted or substituted aryl, aralkyl, heteroaryl, heteroaralkyl or a cycloalkyl group with or without a heteroatom like S, O, N; and the pharmaceutically acceptable salts thereof.