Synthesis and biological evaluation of highly potent analogues of epothilones B and D.

A series of new epothilone B and D analogues incorporating fused hetero-aromatic side chains have been prepared. The synthetic strategy is based on olefin 3 as the common intermediate and allows variation of the side-chain structure in a highly convergent and stereoselective manner. Epothilone analogues 1a-d and 2a-d are more potent inhibitors of cancer cell proliferation than the corresponding parent epothilones B or D.