- New and Efficient Synthesis of 6-Deoxy-L-gulose
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An efficient synthetic procedure for the transformation of D-glucurono-γ-lactone to 6-deoxy-L-gulose (20) in five steps and 52 percent yield is described.The scheme relies on the selective blocking of the 2-(silyl ether) and 3,5-(isopropylidene) hydroxyl groups and then diisobutylaluminum hydride reduction of the lactone carbonyl.An alternate route that relies on the more standard sodium amalgam reduction of the lactone triol was found to be technically inefficient and to result in a poor overall yield.
- Ireland, Robert E.,Wilcox, Craig S.
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- Identification of catabolic pathway for 1-deoxy-D-sorbitol in Bacillus licheniformis
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1-Deoxy-D-sorbitol, the 1-deoxy analogue of D-sorbitol, has been detected in human urine as well as in natural herbs and spices. Although there are sporadic reports about 1-deoxy-D-sorbitol dehydrogenase, the complete catabolic pathway of 1-deoxy-D-sorbitol remains unsolved. Informed by the promiscuous activities of fructose-6-phosphate aldolase (FSA) which is involved in the sorbitol (glucitol) utilization (gut) operon and guided by the large scale bioinformatics analysis, we predicted and then experimentally verified the gut operon encoded by Bacillus licheniformis ATCC14580 is responsible for the catabolism of both D-sorbitol and 1-deoxy-D-sorbitol by in vitro activity assays of pathway enzymes, in vivo growth phenotypes, and transcriptomic studies. Moreover, the phylogenetic distribution analysis suggests that the D-sorbitol and 1-deoxy-D-sorbitol catabolic gene cluster is mostly conserved in members of Firmicutes phylum.
- Li, Yongxin,Huang, Hua,Zhang, Xinshuai
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- Modulating Electrostatic Interactions in Ion Pair Intermediates To Alter Site Selectivity in the C?O Deoxygenation of Sugars
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Controlling which products one can access from the predefined biomass-derived sugars is challenging. Changing from CH2Cl2 to the greener alternative toluene alters which C?O bonds in a sugar are cleaved by the tris(pentafluorophenyl)borane/HSiR3 catalyst system. This increases the diversity of high-value products that can be obtained through one-step, high-yielding, catalytic transformations of the mono-, di-, and oligosaccharides. Computational methods helped identify this non-intuitive outcome in low dielectric solvents to non-isotropic electrostatic enhancements in the key ion pair intermediates, which influence the reaction coordinate in the reactivity-/selectivity-determining step. Molecular-level models for these effects have far-reaching consequences in stereoselective ion pair catalysis.
- Bowers, Bekah E.,Gagné, Michel R.,Lowe, Jared M.,Seo, Youngran
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supporting information
p. 17297 - 17300
(2020/07/30)
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- Photolysis of 2-azi-2-deoxy-D-arabino-hexitol and analogous hexitols; the ineffectiveness of certain carbohydrate diazirines as photoaffinity labels
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Three diazirines 2-azi-2-deoxy-D-arabino-hexitol (4), its 1-deoxy analogue (5), and 3-azi-3,6-dideoxy-L-xylo-hexitol (9) were synthesised and their products of photolysis analysed by TLC.Diazirine 4 gave exclusively 2-deoxy-D-arabino-hexose (12), 5 gave predominantly 1,2-dideoxy-D-erythro-3-hexulose (10) and 1-deoxy-D-glucitol (11), and 9 did not yield any main product.Carrying out the irradiation of 4 in D2O gave selectively (2S)-2-deoxy-D-arabino-(2-2H)hexose (12a).The results indicate that photolysis of a diazirine flanked by a hydroxymethyl group, as in compound 4, leads to a rapid and stereoselective intramolecular reaction of the intermediate.This may be an explanation of why compound 4 is ineffective as a photoaffinity reagent for mannitol permease (D-mannitol-specific enzyme II) of the E. coli phosphotransferase system for which it is a substrate.A secondary hydroxymethylene group has a less pronounced effect and still allows some reaction with the medium.
- Lehmann, Jochen,Petry, Stefan
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p. 133 - 142
(2007/10/02)
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- HYDRAZINOLYSIS OF MONOSACCHARIDES: A TWO-STEP SYNTHESIS OF CHIRAL PENTANE-1,2,3-TRIOLS FROM PENTOSES AND OBSERVATIONS ON THE HYDRAZINOLYSIS OF GLYCOPROTEINS AND GLYCOPEPTIDES
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1,2-Dideoxyalditols, the corresponding 1-alkenes, and 1-deoxyalditols are formed in various proportions from D-glucose, D-mannose, L-arabinose, and D-xylose by the action of refluxing hydrazine.Sequential hydrazinolysis, catalytic hydrogenation, and chromatography afford a route to 1,2-dideoxyalditols.For example, 1,2-dideoxy-L-erythro-pentitol is formed from L-arabinose in 42percent yield, and D-xylose is a source of 1,2-dideoxy-D-threo-pentitol (50percent).Under the conditions (anhydrous hydrazine at 100 deg C for 30 h in the absence of air) used Montreuil for the hydrazinolysis of glycoproteins and glycopeptides, no 1,2-dideoxialditol was formed; degradation was incomplete, there being some aldose hydrazone present.Under Kochetkov's hydrazinolysis conditions (105 deg C for 10 h with hydrazinium sulphate), less degradation occured and product from D-galactose was identified as 1-deoxy-D-tagatose hydrazone.
- Williams, J. Michaels
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