Synthesis of the acyclic precursor of an epothilone D analogue

Condensation of separately obtained C¹–C⁹ and C¹⁰–C²¹ chiral blocks under Yamaguchi conditions affords the corresponding ester, an acyclic precursor of an epothilone D analogue. The reaction is accompanied by the formation of a side product of acylation of the starting alcohol by the Yamaguchi reagent.