The present invention is directed to processes for the synthesis of morphinans. In particular, a process for cyclizing a β,γ-bicyclic ketone compound to form a nordihydrothebainone product using the Grewe cyclization reaction is improved by forming a reaction mixture comprising a β.γ-bicyclic ketone compound, a cyclizing acid and a water scavenging cyclization additive. In one embodiment, the Grewe transformation occurs in the presence of an acid anhydride as the cyclization additive. Further, the present invention is directed to processes for converting α,β-bicyclic ketone compounds (e.g., by-products of the Grewe cyclization reaction) to β,γ-bicyclic ketone compounds, wherein the β,γ-bicyclic ketone compounds may be recovered to further undergo Grewe cyclization and form the nordihydrothebainone product.
本发明涉及
吗啡类化合物的合成工艺。特别是通过形成一种包含β.γ-双环酮化合物、一种环化酸和一种
水清除环化添加剂的反应混合物,改进了利用格氏环化反应使β,γ-双环酮化合物环化以形成一种去
氢吗啡酮产物的工艺。在一个实施方案中,格氏转化是在酸酐作为环化添加剂存在的情况下进行的。此外,本发明还涉及将 α,β-双环酮化合物(例如,格列卫环化反应的副产物)转化为 β,γ-双环酮化合物的工艺,其中 β,γ-双环酮化合物可回收以进一步进行格列卫环化反应并形成正二氢土荆皮酮产品。