Derivatization of the C12 C13 functional groups of epothilones A, B and C

Epothilone A reacted with hydrohalic acids to C12 C13 halohydrin regioisomers (ratios: 2:1 – 4:1), whereas epothilone B gave under the same conditions the isomerically pure C12 halo C13 hydroxy derivative. With non-nucleophilic Brønstedt acids and with Lewis acids a highly solvent dependent product distribution and some unexpected rearrangement products were observed. Epothilone C bearing a double bond between C12 and C13 was regioselectively dihydroxylated or hydrogenated at that position.