Phragmalin-type limonoid orthoesters from the twigs of Swietenia macrophylla.

Eleven new phragmalin-type limonoids, swietenitins N-X (1-11), together with a known one, epoxyfebrinin B (12), were isolated from the twigs of Swietenia macrophylla. The structures of the new compounds were established on the basis of spectroscopic methods, and that of compound 1 was confirmed by single-crystal X-ray diffraction. The stereochemistry of epoxyfebrinin B (12) was fully assigned in this study.