Total Synthesis of (±)-Niduterpenoid B

Keywords

(±)-niduterpenoid B - Horner–Wadsworth–Emmons reaction - Knoevenagel condensation - Krapcho decarboxylation - Alcaraz reaction - Johnson–Claisen rearrangement - cyclopropanation

Significance

Niduterpenoid B is characterized by a 5 /5 /5 /5 /3 /5 hexacyclic framework featuring 13 contiguous stereocenters, four of which are quaternary. The total synthesis by Tu and co-workers capitalizes on a cascade reaction wherein the tetraquinane scaffold, with its stereocenters, is rapidly assembled. The full core of the molecule is later accessed via a rhodium-mediated cyclopropanation.

Comment

Cyclobutanone A, assembled by [2 + 2] cycloaddition of cyclopentadiene and methoxy(methyl)ketene, was converted into key triene E. Exposure of E to Lewis and Brønsted acid catalysis initiated the Nazarov cyclization/double ring expansion/elimination reaction which, after Krapcho decarboxylation, returned tetraquinane F. The highly strained three-membered ring in J was installed via cyclopropanation of diazo ketone I, which served as synthetic intermediate to complete the synthesis of niduterpenoid B.

Publication History

Article published online:
21 November 2024