Derivatives of 4-Amino-4-deoxy-D-glucose^1a

Synthesis of Urea‐Tethered Disaccharides in Water

“…[15] The synthesis of 4-aminohexopyranose 21 began with Lewis acid catalyzed glycosylation of p-methoxyphenol with pentaacetyl-d-galactose 31 under thermodynamically controlled conditions (SnCl 4 , CH 2 Cl 2 , room temperature, 27 h) to furnish p-methoxyphenyl-a-galactoside 32 in 66 % yield after recrystallization (Scheme 10). [17] Nucleophilic S N 2 displacement of mesylate 35 with sodium azide in DMF proceeded smoothly (140 8C, 3.5 h) to afford the azide 36 in 77 % yield. [17] Nucleophilic S N 2 displacement of mesylate 35 with sodium azide in DMF proceeded smoothly (140 8C, 3.5 h) to afford the azide 36 in 77 % yield.…”

Syntheses of cellotriose and cellotetraose analogues as transition state mimics for mechanistic studies of cellulases

“…Triflates 26a and 26b were readily prepared from methyl a-and b-D-galactopyranosides, respectively. 31,32 Aqueous sodium hydroxide removed all esters of 27 to give sulfur-substituted analogues 3a and 3b after ion exchange column chromatography (Dowex 50 W, H + form). Cellotetraose derivative 4 was obtained via coupling between 20 and 24 followed by similar deprotection as mentioned above.…”

Sugar enolones: synthesis, reactions of preparative interest, and γ-pyrone formation

“…However, in many cases, separations can be avoided as, for example, in the preparation of the highly crystalline tribenzoylenolone (l) from the hexenitOL (23). At low temperature, chlorination of (23) affords a mixture of ~-D-manno dichloride (24) and the benzoxonium salt (25), which only at room temperature is converted-rnto the ß-D-gluao dichloride~26). Hence, when a low temperature chlorination of (23) is followed by hydrolysis with water, a mixture of 24 and the hexosulose-27 is obtained, which on brief treatment with boiling--benzene and moist sodium hydrogen carbonate yields enolone 1, readily separable from 24 by fractional crystallisation.…”