An intermediate in the synthesis of Epothilones. Epothilones are polyketide natural products that inhibit cancer cells by a mechanism similar to paclitaxel, and also are effective against paclitaxel-resistant tumours. Epothilone D is in phase I clinical testing of in patients with advanced solid tumours. Epothilone D is a cytotoxic macrolide that stabilises malignant cells’ microtubules and arrests mitosis, a characteristic it shares with other epothilones. They bind to the same hepatic sites as does paclitaxel (Taxol) in a 1:1 stoichiometric ratio of a, b-tubulin heterodimers.