Aphanalides A–H, ring A-seco limonoids from the fruits of Aphanamixis polystachya

Eight new ring A-seco limonoids, aphanalides A–H (1–8) were isolated from the fruits of Aphanamixis polystachya. Aphanalides A–C (1–3) are the first examples of ring A-seco limonoids with an unusual oxetane ring between C-7 and C-14. The structures of aphanalide A (1) and aphanalide C (3) were confirmed by single-crystal X-ray studies. Their structures including absolute stereochemistry were established on the basis of extensive NMR spectroscopic analysis, by comparison of experimental and calculated electron circular dichroism (ECD) and by X-ray diffraction, representing the first report of assignment of absolute configuration of such type ring A-seco limonoids. The biogenetic origin of aphanalides A–D (1–4) from aphanalides E–H (5–8) was also postulated.