Skeletal Transformations of Terpenoid Forskolin Employing an Oxidative Rearrangement Strategy.

The skeletal transformations of diterpenoid forskolin were achieved by employing an oxidative rearrangement strategy. A library of 36 forskolin analogues with structural diversity was effectively generated. Computational analysis shows that 12 CTD compounds with unique scaffolds and ring systems were produced during the course of this work.

Alkylide derivatives of diphyllin: synthesis and preliminary anticancer evaluation.

Fourteen diphyllin 4-C-substituted alkylide derivatives were designed and synthesized using a Heck coupling and subsequent hydrogenation reaction. Olefins 3g and 3i exhibited the highest cytotoxicity on breast cancer cell lines MCF-7 with IC50 values of 0.08 and 0.07 µM, and they showed weaker V-ATPase inhibitory potency compared to diphyllin.

Synthesis of intramolecular cross-coupling analogues of forskolin.

A ring distortion strategy was applied to the synthesis of a series of intramolecular cross-coupled analogues of forskolin 1. Treatment with palladium acetate, forskolin underwent an intramolecular cross-coupling reaction to generate a novel cycloalkene ether 2 in 85% yield. Under the same conditions, a series of forskolin ester analogues 4a-4d were prepared from 1-OH ester derivatives of forskolin 3a-3d in 85-93% yields. Treating cycloalkene ether 2 with aryl iodides in the presence of a palladium catalyst afforded Z-isomers arylation products 5a-5e in a stereoselective manner in 70-85% yields.