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[摘要]：The ethylene glycol ketal I (R6aR6b = OCH2CH2O, R7 = H, R8R14 = bond) of neopinone was prepd. in a one-pot procedure by the reaction of thebaine (R6a = OMe, R6bR7 = bond, R8R14 = bond) with ethylene glycol in the presence of p-toluenesulfonic acid. The ketal was also an intermediate in the conversion of thebaine to hydrocodone I (R6aR6b = O, R7 = R8 = R14 = H) with ethylene glycol and Pd(OAc)2, followed by hydrogenation. Addnl., a one-pot procedure for the conversion of thebaine to hydrocodone was achieved by employing palladium catalysis in aq. medium. Palladium serves a dual purpose in this transformation, first for the activation of the dienol ether of thebaine and second as a hydrogenation catalyst. This procedure was found to be comparable to the two-step protocol which employs diimide redn. of thebaine followed by acid-catalyzed hydrolysis of the resulting 8,14-dihydrothebaine to hydrocodone. Exptl. and spectral data are provided for all compds. |
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