A Lewis acid BF3•Et2O-mediated intramolecular cycloaddition reaction of mahanimbine (1) is described. Three cycloadducts, bicyclomahanimbine (2), cyclomahanimbine (3) and murrayazolinine (4) were obtained. The structural characterization of these compounds was determined by 1D and 2D NMR experiments. These compounds showed no cytotoxic activity against human MRC-5 cells (IC50 > 60 μg/mL). Compound 3 showed the highest inhibition cytotoxic effects against HeLa and HL-60 cancer cells with IC50 values of 10.0 and 28.7 μg/mL, respectively. This strategy opens a new approach for the synthesis of biologically significant cyclic monoterpenoid pyrano[3,2-a]carbazole alkaloids.

描述了路易斯酸BF3•Et2O介导的马尼宾滨（1）的分子内环加成反应。获得了三个环加合物，即双环马哈宁滨（2），环马哈宁滨（3）和莫拉唑啉（4）。这些化合物的结构表征通过1D和2D NMR实验确定。这些化合物对人MRC-5细胞无细胞毒活性（IC50> 60μg/ mL）。化合物3对HeLa和HL-60癌细胞的抑制作用最高，IC50值分别为10.0和28.7μg/ mL。该策略为生物学上重要的环状单萜吡喃并[3,2-a]咔唑生物碱的合成开辟了新途径。