unique biological activity, make the natural occurring apoptolidin (1) a challenging synthetic target. The retrosynthetic analysis revealed five key building blocks-three for the construction of the macrolide ring B and two prospective pendant saccharide units-which were synthesized in a highly convergent manner and then connected. Apoptolidin's rather labile nature proved particularly challenging in
An effective synthesis of the pentasaccharide hapten from the glycopeptidolipid antigen of Mycobacterium avium serovar 12 in the protected p-nitrophenyl glycoside, using a 3+2 block synthesis strategy, is described. (C) 2602 Elsevier Science Ltd. All rights reserved.