Total synthesis and antibacterial activities of a macrocyclic lactone antibiotic A26771B (1) and all its isomers (2, 3, and 4) are discussed. The starting 8, 9, 10, 12-tetra-O-benzyl-2, 3, 4, 5, 11-pentadeoxy-aldehydo-D-xylo-(E)-6-dcdecenose derived from D-glucose reacted with racemic Wittig reagent,(3-hydroxybutyl) triphenylphosphonium iodide to give 1, 3, 4, 5-tetra- O-benzyl-2, 8, 9, 10, 11, 14, 16-heptadeoxy-DL-glycero-L-xylo-hexadeca-6, 12-dienitol, ...