STRUCTURE AND ABSOLUTE STEREOCHEMISTRY OF 19-EPI-(+)-ECHITOVENILINE A NEW INDOLE ALKALOID OF THE LEAVES OF ALSTONIA VENENATA R.BR.

Article abstract of DOI:10.1016/S0040-4020(01)92058-7

19-Epi-(+)-echitoveniline, a new indole alkaloid of the leaves of Alstonia venenata R.Br., has been shown the possess the structure and absolute stereochemistry represented by 5b on the basis of spectral and chemical evidence.A mechanistic rationale for the dependence of the mode of LAH reduction of the δ-lactone 11 on its configuration at C-19 has been offered.The influence of the C-19 configuration on the chemical shift values of the C-16 carbomethoxy protons in the 19-aroyloxy-(+)-and (-)-vincadifformine alkaloids has been discussed.