Gelegamines A–E: five new oxindole alkaloids from Gelsemium elegans

Tetrahedron
2009.0

Abstract

Five new oxindole alkaloids, gelegamines A–E (1–5), were isolated from the roots of Gelsemium elegans. Their structures were extensively elucidated on the basis of spectroscopic analysis. Among them, the epoxy ring (C-19/C-20) of gelegamine A (1) was assigned as a-orientation by ROESY experiment and DFT method at B3LYP/6-31g(d) level, and gelegamine B (2) is the first humantenine-type alkaloid with 19-(E) ethylidene configuration. The absolute configurations of gelegamines A–E (1–5) were established on biosynthetic consideration coupled with CD experiments.

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