The acid-catalyzed rearrangement of morphine (1), codeine (3), 3-deoxynormorphine (14) and Ncyclopropylmethyl- 3-deoxynormorphine (11) was investigated with methanesulfonic acid. The yield in the rearrangement reaction was significantly improved using milder reaction conditions, compared to the earlier reported methods. As an evidence for the mechanism of the acid-catalyzed rearrangement of morphinans, the diene intermediate 13 was isolated. A new method, using boron trifluoride etherate was elaborated for the rearrangement of morphinandienes.
Keywords: Morphinans, morphine, codeine, acid-catalyzed rearrangement
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