title: Synthesis and testing of 2-deoxy-2,2-dihaloglycosides as mechanism-based inhibitors of alpha-glycosidases.
abstract: The synthesis of a series of 2-deoxy-2,2-dihaloglycosyl halides as potential alpha-glycosidase inactivators has been achieved via the halogenation of protected 2-fluoroglycal precursors. Direct chlorination of per-O-acetylated 2-fluoro-d-glucal and 2-fluoromaltal followed by basic deprotection yielded the corresponding 2-chloro-2-deoxy-2-fluoroglycosyl chlorides. Reaction of the per-O-acetylated 2-fluoroglycals with acetyl hypofluorite or Selectfluor yielded the 2-deoxy-2,2-difluoroglycosyl derivatives, which were converted to their alpha-chlorides using thionyl chloride and deprotected under basic conditions. Trinitrophenyl glycosides of the 2-deoxy-2,2-difluoro mono- and disaccharides were synthesized by arylation of the hemiacetals with picryl fluoride, then deprotected with HCl in methanol. All three monosaccharide derivatives caused active site-directed, time-dependent inactivation of yeast alpha-glucosidase via the trapping of covalent glycosyl-enzyme intermediates, and kinetic parameters for inactivation by each compound were determined. Surprisingly neither of the 2-deoxy-2,2-dihalomaltosyl chlorides caused time-dependent inactivation of human pancreatic alpha-amylase, despite the fact that the trinitrophenyl 2-deoxy-2,2-difluoromaltoside functioned in that mode. The trinitrophenyl glycosides appear to be approximately 1000-fold more reactive than the corresponding chlorides in the enzyme active sites.
authors.affiliation: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Ran
authors.initials: R
authors.lastname: Zhang
authors.forename: John D
authors.initials: JD
authors.lastname: McCarter
authors.forename: Curtis
authors.initials: C
authors.lastname: Braun
authors.forename: Wai
authors.initials: W
authors.lastname: Yeung
authors.forename: Gary D
authors.initials: GD
authors.lastname: Brayer
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Withers
mesh_terms: D017606:Chlorine Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D017611:Fluorine Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry; D010179:Pancreas / Q000187:drug effects / Q000201:enzymology; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology
chemical_list: D017606:Chlorine Compounds; D004791:Enzyme Inhibitors; D017611:Fluorine Compounds; D006027:Glycosides; D006026:Glycoside Hydrolases; D010100:Oxygen