Facile synthesis of sulfonium ion derivatives of 1,5-anhydro-5-thio- l-fucitol as potential α- l-fucosidase inhibitors

Abstract

Five sulfonium ion derivatives with 1,5-anhydro-5-thio- l-fucitol as a core structure were efficiently synthesized as potential α- l-fucosidase inhibitors. The key unit, the tri- O-benzyl derivative of l-fucitol, was readily synthesized from methyl α- d-mannopyranoside. Alkylation with methyl iodide or 5-methoxycarbonyl-1-pentyl iodide in acetonitrile containing AgBF 4 afforded the corresponding alkylated sulfonium tetrafluoroborates. Alternatively, ring opening of three 1,3-cyclic sulfates in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) containing K 2CO 3 afforded the corresponding zwitterionic sulfonium sulfates.