Synthesis of (+)-Moluccensin G and (+)-Krishnolide F

Keywords

(+)-moluccensin G - (+)-krishnolide - Liebeskind–Srogl coupling - interrupted photochemical Nazarov reaction - benzoin condensation/acyl migration - Riley oxidation - acyloin rearrangement

Significance

Ding, Xuan, and co-workers present the total synthesis of the phragmalin-type limonoid ( + )-moluccensin G and the khayanolide-type limonoid ( + )-krishnolide F alongside two other natural products. Inspired by the proposed biosynthesis, the authors achieve interconversion between the skeletons of the two limonoid classes through acyloin rearrangement.

Comment

Dienone C was accessed through Liebeskind–Srogl coupling between stannane A and thioester B. Subsequent photochemical interrupted Nazarov reaction gave rise to pentacycle D. After elimination, desaturation and acetal deprotection, aldehyde E was obtained. Treatment with triazolium salt F and sodium acetate triggered a benzoin condensation/acyl transfer cascade.