One-pot synthesis of the naturally occurring dimeric carbazole alkaloid murranimbine and its analogue

Murranimbine, a naturally occurring dimeric carbazole alkaloid, isolated from the root bark of Murraya euchrestfolia was synthesized in one step by the application of Lewis acid (BF3–Et2O) on its monomer girinimbine. A new dimer of koenidine was also synthesized following the same procedure. Structures of these dimeric carbazole alkaloids were determined by detailed spectral analysis.