STUDIES ON THE BIOMIMETIC SYNTHESIS OF YUEHCHUKENE——A NOVEL ANTI-IMPLANTATION BIS-INDOLE ALKALOID

Yuehchukene (Ⅵ), isolated from the roots of Murraya paniculata (named in China as Jiu-Li-Xiang), is a novel bisindole alkaloid with anti-implantation and thus anti-early pregnancy activities in rats. In this paper, the title compound (Ⅵ) was synthesized from indole through the following steps: formylation to give indole-3-carboxaldehyde(Ⅰ), then condensation with acetone, toluenesulfonylation of the nitrogen atom, Witting reaction, deprotection of the protecting group to give 3-isoprenylindole(Ⅴ) and intermolecular Diels-Alder cyclization successively. The overall yield was 7.5%. The spectral data (IR, ¹HNMR, UV and MS spectrum) and physical constants of the synthetic yuehchukene were identical with the natural product. The synthetic sample was administered to rats at 2 mg and 4 mg/kg. It was found to be 100% and 50% active for preventing implantation and terminating early pregnancy respectively. Meanwhile, two by-products, trimer and tetramer of Ⅴ, were obtained.