Biosynthetic studies on the α-glucosidase inhibitor acarbose: the chemical synthesis of isotopically labeled 2-epi-5-epi-valiolone analogs Original Research Article

2-epi-5-epi-Valiolone is a cyclization product of the C7 sugar phosphate, sedoheptulose 7-phosphate, involved in the biosynthesis of the aminocyclitol moieties of acarbose, validamycin, and pyralomicin. As part of our investigation into the pathway from 2-epi-5-epi-valiolone to the valienamine moiety of acarbose, we prepared 1-epi-5-epi-(6-2H2)valiolol [(6-2H2)-6], 5-epi-(6-2H2)valiolol [(6-2H2)-17], 1-epi-2-epi-5-epi-(6-2H2)valiolol [(6-2H2)-12] and 2-epi-5-epi-(6-2H2)valiolamine [(6-2H2)-11]. Compounds (6-2H2)-6 and (6-2H2)-17 were synthesized from 2,3,4,6-tetra-O-benzyl-d-glucopyranose in 10 and seven steps, respectively, whereas (6-2H2)-12 and (6-2H2)-11 were synthesized from 2,3,4,6-tetra-O-benzyl-d-mannopyranose in eight and 10 steps, respectively.