Total syntheses of epothilones B and D

A convergent, total synthesis of epothilones B and D is described. The key steps are Normant coupling to establish the desired (Z)-stereochemistry at C12-C13, Wadsworth-Emmons olefination of methyl ketone with the phosphonate ester, diastereoselective aldol condensation of aldehyde with the enolate of keto acid derivatives to form the C6-C7 bond, selective deprotection of acid 52, and macrolactonization.