Elsevier, Tetrahedron Letters, 29(43), p. 5131-5134
DOI: 10.1016/s0040-4039(02)00981-4
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A novel labdane diterpene alkaloid, vitexlactam A (1) was isolated as a prism from the n-hexane extract of the fruits of Vitex agnus-castus through normal and reverse phase column chromatography. Its structure was elucidated to be 6β-acetoxy-9α-hydroxy-13(14)-labden-16,15-amide, based on chemical and spectral evidences including 1D and 2D NMR spectra. The structure was confirmed by X-ray crystallographic analysis. Compound 1 is the first naturally occurring labdane diterpenoid containing an α,β-unsaturated γ-lactam moiety.