A highly convergent, enantioselective total synthesis of the potent antitumor agent apoptolidin A, has been completed. The key transformations include highly selective glycosylations to attach the C27 disaccharide and the C9 6′-deoxy-l-glucose, a cross metathesis to incorporate the C1-C10 trienoate unit, and a Yamaguchi macrolactonization to complete the macrocycle. Twelve stereocenters in the polypropionate segments and sugar units were established through diastereoselective chlorotitanium enolate aldol reactions
