4271-28-7

The products of nitrous acid deamination of per-O-methylated 2-amino-2-deoxy-D-glucitol and of 2-amino-2-deoxy-3-O-β-D-galactopyranosyl-D-glucitol and its per-O-methylated derivative have been characterized by g.l.c.-mass spectrometry after treatment with sodium borodeuteride and further substitution by acetylation, methylation, or (trideuteriomethyl)ation.The results confirm that the most important reaction pathway (1) involves a 12-hydride shift, to give 2-deoxy-D-arabino-hexoses, but that significant side-reactions include (2) solvolytic displacement at C-2, (3) a 32-hydride shift to give 2-deoxy-2-D-erythro-3-hexuloses, and (4) a C-4C-2 migration to give 2-deoxy-2-C-(hydroxymethyl)-D-ribose and -D-arabinose.Reactions (3) and (4) result in elimination of the original 3-O-substituents, with the exposure of new reducing groups, from oligosaccharides terminated by 3-O-substituted 2-amino-deoxyhexitols.

Chitin is a potential resource for the production of renewable organonitrogen compounds, as it contains biologically fixed nitrogen. Hydrolysis of chitin followed by hydrogenation gives the sugar alcohol named 2-acetamido-2-deoxysorbitol (ADS). The dehydration condensation of ADS produces 2-acetamido-2-deoxyisosorbide (ADI), which is a prospective precursor of nitrogen-containing polymers. However, the conversion of ADS to ADI in previous works needed a large amount of CF3SO3H as a superstrong acid catalyst, which is high cost and requires special corrosion-resistant equipment. In this work, we have found that H3PO3, a weak acid, can convert ADS to ADI. Possibly, H3PO3alters the reaction mechanism from a simple acid-catalysed dehydration cyclisation to a cyclisationviaphosphite esters. Density functional theory calculations suggest that the modified pathwayviathe phosphite esters significantly reduces the activation energy. In addition, the reducing ability of the acid likely decreases the formation of condensation by-products.

Chitin is the second most abundant biomass and characteristically contains nitrogen atoms in its monomer units. These favourable features promote chitin to be a potential resource for renewable organonitrogen compounds. 2-Acetamido-2-deoxysorbitol (ADS) is an attractive target in the derivatives of chitin, but the conversion of chitin to ADS has not been reported so far. In this work, we demonstrate the catalytic conversion of chitin to ADS using mechanocatalysis in the presence of H2SO4 and subsequent hydrolytic hydrogenation by H2SO4 and Ru/TiO2 without any purification process. Our study clarified that the yield of ADS is strongly influenced by the reaction temperature and pH. The hydrolysis favourably proceeds at high temperature and low pH (2.0), but the hydrogenation needs a low temperature and a specific pH of 3-4 to achieve high selectivity. Specifically, in the hydrogenation step, an acid causes various side-reactions of amide and hemiacetal groups especially in the presence of a Ru catalyst, whereas even a small amount of base drastically accelerates the retro-aldol reaction to form erythritol and N-acetylethanolamine. Therefore, a one-pot but two-step reaction is necessary to optimise both the hydrolysis and hydrogenation steps and maximise the overall yield of ADS up to 52%.

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