“…Condensation of 37 with triphenylphosphine and subsequent aza-Wittig-type reaction with either carbon disulfide or methyl, phenyl, or 2,3,4,6-tetra- O -acetyl-β- d -glucopyranosyl isothiocyanate led to the isothiocyanate 38 or carbodiimide derivatives 42 − 44 , respectively. Nucleophilic addition of methylamine, aniline, and 2,3,4,6-tetra- O -acetyl-β- d -glucopyranosylamine to 38 yielded the thiourea adducts 39 − 41 , respectively, whereas acid-catalyzed addition of water to the heteroallene group of 42 − 44 afforded the corresponding oxocompounds 45 − 47 (Scheme 5). …”
A practical synthesis of polyhydroxylated 6-oxa-nor-tropanes incorporating the essential structural features of calystegine B(2) from 5-deoxy-5-thioureido and 5-ureido-L-idofuranose precursors is presented. The methodology relies on the ability of pseudoamide-type nitrogen atoms (thiourea, urea, and carbamate) to undergo nucleophilic addition to the masked aldehyde group of the monosaccharide. The generated hemiaminal functionality may further undergo in situ intramolecular glycosidation to give the bicyclic aminoacetal compounds, the whole process being favored by the anomeric effect. A series of derivatives bearing different substituents at nitrogen has been prepared and screened against several glycosidases in comparison with xylonojirimycin-type piperidine analogues. Interestingly, strong and highly specific inhibition of bovine liver beta-glucosidase was observed for 6-oxacalystegine B(2) analogues incorporating aromatic pseudoaglyconic groups. On the basis of these data, a 1-azasugar inhibition mode is proposed for this family of glycomimetics.
“…Condensation of 37 with triphenylphosphine and subsequent aza-Wittig-type reaction with either carbon disulfide or methyl, phenyl, or 2,3,4,6-tetra- O -acetyl-β- d -glucopyranosyl isothiocyanate led to the isothiocyanate 38 or carbodiimide derivatives 42 − 44 , respectively. Nucleophilic addition of methylamine, aniline, and 2,3,4,6-tetra- O -acetyl-β- d -glucopyranosylamine to 38 yielded the thiourea adducts 39 − 41 , respectively, whereas acid-catalyzed addition of water to the heteroallene group of 42 − 44 afforded the corresponding oxocompounds 45 − 47 (Scheme 5). …”
A practical synthesis of polyhydroxylated 6-oxa-nor-tropanes incorporating the essential structural features of calystegine B(2) from 5-deoxy-5-thioureido and 5-ureido-L-idofuranose precursors is presented. The methodology relies on the ability of pseudoamide-type nitrogen atoms (thiourea, urea, and carbamate) to undergo nucleophilic addition to the masked aldehyde group of the monosaccharide. The generated hemiaminal functionality may further undergo in situ intramolecular glycosidation to give the bicyclic aminoacetal compounds, the whole process being favored by the anomeric effect. A series of derivatives bearing different substituents at nitrogen has been prepared and screened against several glycosidases in comparison with xylonojirimycin-type piperidine analogues. Interestingly, strong and highly specific inhibition of bovine liver beta-glucosidase was observed for 6-oxacalystegine B(2) analogues incorporating aromatic pseudoaglyconic groups. On the basis of these data, a 1-azasugar inhibition mode is proposed for this family of glycomimetics.
“…When per O-acetylated b-D-glucopyranosylamine and glucosamine hydrobromides 29,30 (Table 1, entries 7 and 8, respectively) were used, an equivalent of Et 3 N was added to the reaction mixture.…”
“…Initial Approach to the Synthesis of Glucopyranosyl Isocyanates. Our initial plan for the synthesis of the glucopyranosyl isocyanates relied upon the reaction of glucopyranosylamines with phosgen equivalent (COX 2 ), because a similar reaction of the glucopyranosylamines with thiophosgene for the preparation of the glucopyranosyl isothiocyanates has been well studied . In addition, we planned to prepare both the α- and β- d -glucopyranosylamines by reducing the α- and β- d -glucopyranosyl azides.…”
A new, one-pot, two-stage procedure for the preparation of the alpha- and beta-D-glucopyranosyl ureas has been developed. Oxidation of glucopyranosyl isocyanides provides glucopyranosyl isocyanates, which can be trapped in situ with amines to afford good yields of glucopyranosyl ureas. Application of this method establishes the successful synthesis of the hitherto unknown N,N'-di-alpha,alpha- and alpha,beta-D-glucopyranosyl ureas.
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