Insect Antifeedants from <i>Croton </i><i>j</i><i>atrophoides</i>:  Structures of Zumketol, Zumsenin, and Zumsenol

Abstract

Three new A-seco limonoids, zumketol (1), zumsenin (2), and zumsenol (3), were isolated from a methanol extract of Croton jatrophoides by bioassay-guided fractionation, and their structures were determined by NMR analysis. The alpha-ketol 1 may be biosynthesized via the intramolecular acyloin condensation of a dicarboxylate intermediate.