Triconoids A–D, Four Limonoids Possess Two Rearranged Carbon Skeletons from Trichilia connaroides

Four limonoids, triconoids
A–C (1–3) possessing a new
rearranged mexicanolide skeleton and triconoid
D (4) furnishing a new rearranged 1,2-seco-phragmalin
skeleton, were isolated from the Nepalese plant Trichilia
connaroides. Two rearranged limonoid skeletons sharing
an F ring of methyl 5-oxotetrahydrofuran-2-carboxylate were postulated
to be formed biosynthetically via a very unique chemical cascade.
Their structures were fully accomplished by spectroscopic data, single-crystal
X-ray diffraction, and electrostatic circular dichroism analysis.