Deoxy acetyl derivative

Table IV. Comparison of Anomeric Proton (Hi) Chemical Shifts for Free and Acetylated D-gluco and D-mannopyranoses With Those of Related 2-Deoxy Sugar Derivatives. Effect of Replacing an Axial or an Equatorial C2-Methylene Proton With a Hydroxy or Actetoxy Substituent...

Proton coupling-constants were determined65 for the tri-O-acetyl derivatives of bis(ethylsulfonyl)-a-D-lyxopyranosylmethane [2,6-anhydro-l,l-bis(ethylsulfonyl)-l-deoxy-D-galactitol] (29) and bis(eth-... 

All of the stereoisomerie methyl 2,3-anhvdro-6-deoxy-DL-hexo-pyranosides have been prepared by epoxidation of 2,3-unsaturated pyranosides (328-331, R = Me) with hydrogen peroxide-benzo-nitrile. The H-n.m.r. data of their 4-O-acetyl derivatives were reported, and discussed in connection with configurational and conformational assignments.223 The1 regio- and stereo-selectivity of the... 

Regioselective deacylation has also been observed189 in the acid-catalyzed transesterification of some 3, 5 -di-0-acetyl-2 -deoxy-2 -halo-uridines in methanol to give the corresponding 3 -0-acetyl derivatives in yields of 36-66%. The presence of the 2-halogen substituent seems essential for the selectivity in the case of 2, 3, 5 -tri-0-acetyl-uridine, no significant differences in the reaction rates of the acetyl groups towards transesterification were apparent. 

Quite analogous ring-closures occur when the 1-O-acetyl derivatives of the rhamnopyranose and talopyranose derivatives are treated with sodium azide in N,N-dimethylformamide. l-O-Acetyl-6-deoxy-2,3-0-isopropylidene-4-0-mesyl-a-L-mannopyranose is converted exclusively into l,4-anhydro-6-deoxy-2,3-0-isopropylidene-/3-L-talo-pyranose. In this instance, the azide nucleophile attacks the l-O-ace-tyl group, liberating an 0-1 oxide ion which reacts with inversion of C-4. The 4-epimeric, l-O-acetyl-6-deoxy-talose derivative gives 60% of the direct inversion product l,4-anhydro-6-deoxy-2,3-0-isopropyli-dene-a-L-mannopyranose, together with other products.50... 

After hydrolysis of carboxyl-reduced and partially desulfated heparin with hydrochloric acid, Wolfrom and coworkers117 isolated a disaccharide that was identified118 as 2-amino-2-deoxy-4-0-a-D-glucopyran-osyl-D-glucopyranose ( maltosamine ) hydrochloride, which gave a crystalline N-acetyl derivative (50). This structure was subsequently... 

Migration of the ring-oxygen atom also occurred predominantly in the deamination of the tetra-O-acetyl derivatives of 2-amino-2-deoxy-a- and -/3-D-glucopyranose to give 3,4,6-tri-0-acetyl-2,5-anhydro-D-mannose (10), which is unstable and readily eliminates acetic acid to... 

Likewise, 5-C-(butylphosphinyl)-5-deoxy-D-xylopyranose 33 was obtained34 from 25 (R = Ac or Bz) by way of the phosphine oxide intermediate 28 (R = Bu). An acetyl derivative having structure 38, namely, 1,2,3,4-tetra-O- acetyl- 5-C- [(R)- butylphosphinyl]-5- deoxy- a -D-xylo-pyranose,33 crystallized from the diastereomeric mixture of the per-O-acetylated products from 33. 

The 2-0-(2-amino-2-deoxy-D-galactosyl)glycerol (34, R = H) was smoothly degraded by nitrous aoid to glycerol and 2,5-anhydro-D-talose (3S), and the W-acetyl derivative (35, R = Ac) reduced 1 molar proportion of periodate, giving neither formaldehyde nor formic acid during (84) P. J. Stoffyn and R. W. Jeanlos, Arch. Biochem. Biophyi., 52, 373 (1054). 

Vercellotti et al. (65) studied the rates of / -elimination for O-benzyl ethers of O-glycosyl-N-(2,4-dinitrophenyl)-L-serine and L-threonine methyl esters in non-aqueous solvents using various bases. The corresponding acetyl derivatives of 2-acetamido-2-deoxy-D-galactose were also included. Generally, these substances were highly reactive, but the nature of the solvent and the base type were influencing factors. Thus, no elimination occurred in benzene when trimethylamine was used as base. 

Hi) Reduction of Glycosyl Halides with Radical Rearrangement. The reduction of acetylated or benzoylated halides or selenides with a low concentration of tributylstannane leads to 2-deoxy sugar derivatives (Scheme 11). The driving force of this radical reaction is the 1,2-cA-selective migration of an ester group because of the stabilization of the radical at C-2.46... 

A common example that has been isolated from many plant polysaccharides is 2-0-(4-0-methyl-a-D-glucopyranosyluronic acid-D-xylose (64). Hyalobiouronic acid, [2-amino-2-deoxy-3-0-(/f-D-glucopyranosyluronic acid)-D-glucose] (65), whose A-acetyl derivative is the repeating unit of... 

P. A. McNicholas, M. Batley, and J. W. Redmond, Synthesis of methyl pyranosides and furanosides of 3-deoxy-D-marcrco-oct-2-ulosonic acid (KDO) by acid-catalysed solvolysis of the acetylated derivatives, Carbohydr. Res., 146 (1986) 219-231. 

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