A new synthetic development of the bioactive benzo[c]phenanthridines based on a microwave-assisted electrocyclic reaction of aza 6π-electron system

全合成了非型苯并[c]菲thridine生物碱、去硝基丁、去萘维辛、异癸碱、去切赤藓碱、去血碱和花椒碱，以及苯并[c]菲thridine生物碱、硝基丁、鸟胺、血碱、切赤藓碱和broussonpapyrine。以2-溴苯甲醛与（3,4-二氢-6,7-亚甲二氧基）硼酸蒎醇酯为原料，经Suzuk-Miyaura交叉偶联反应，通过微波辅助电环反应构建了四环11,12-二氢苯并[c]菲咯啶。此外，通过核磁共振光谱分析确定了其确切结构为车车菊碱。

Total syntheses of the nor-type of benzo[c]phenanthridine alkaloids, nornitidine, noravicine, isodecarine, norchelerythrine, norsanguinarine, and zanthoxyline, and benzo[c]phenanthridine alkaloids, nitidine, avicine, sanguinarine, chelerythrine and broussonpapyrine were achieved. The key step was the construction of tetracyclic 11,12-dihydrobenzo[c]phenanthridine using a microwave-assisted electrocyclic reaction of the 2-cycloalkenylbenzaldoxime methyl ether as an aza 6π-electron system, which was derived in two steps from a Suzuk-Miyaura cross-coupling reaction of 2-brombenzaldehyde with (3,4-dihydro-6,7-methylenedioxynaphthyl)boronic acid pinacol ester. In addition, the exact structure of broussonpapyrine was determined to be chelerythrine by NMR spectral analysis.