A novel and efficient synthesis of naturally occurring 1-methoxycarbazoles glycozolicine, mukolidine, and mukoline is developed by applying a regioselective Diels-Alder reaction of a 4,5-dimethyleneoxazolidin-2-one with acrolein. The cycloadduct is transformed to the corresponding functionalized diarylamine. The key palladium-catalyzed cyclization/deformylation cascade reaction of the latter leads to glycozolicine in high overall yield. Oxidation of the C6 methyl group provides the 6-formylcarbazole mukolidine, which is reduced to the respective natural alcohol mukoline.
通过应用 4,5-二亚甲基
恶唑烷-2-酮与
丙烯醛的区域选择性 Diels-Alder 反应,开发了一种新型高效合成天然 1-甲氧基
咔唑的方法。环加合物转化为相应的官能化二芳基胺。后者在关键的
钯催化下发生环化/脱甲酰化级联反应,从而以较高的总收率制得乙二唑啉。C6 甲基的氧化反应产生了 6-甲酰基
咔唑 mukolidine,再将其还原成相应的天然醇 mukoline。