Glucitol deamination

The occurrence of some substitution in the deamination of 2-amino-2-deoxy-/3-D-mannopyranosides131 152 (72), and its absence in the reaction of the a-D-pyranoside150 69, must be due to the steric effect of the axial anomeric substituent which (in the a-D-pyran-oside) hinders the approach of the nucleophile (water) to either the C-2 carbonium ion or to C-2 of the diazonium ion. The glucose and glucitol tentatively detected as minor products in the deamination of 72 (R = D-glucose residue and R = D-glucitol residue) presumably arose by way of a hydride shift of H-l to C-2. 2-Deoxy-D-glucono-1,5-lactone (75) was not detected, as it would probably have. o,... 

On deamination, 2-amino-l,5-anhydro-2-deoxy-l>mannitol gave l,5-anhydro-2-deoxy-D-eryf/iro-3-hexulose as the major product.54 The substitution product 1,5-anhydro-D-glucitol was formed to a small extent, and inversion again predominated, as with other axial amines (60, 72, and methyl 4-amino-4-deoxy-a-D-galactopyranoside) this is in accord with the predominant inversion of configuration reported for deamination, in water-rich media, of simple cyclohexyla-mines,154 and aminodecahydronaphthalenes39 in which the amino group is axial. As discussed previously (see p. 15), the extent of inversion can vary considerably with the nature of the solvent, and steric factors appear to be important in deaminations of per-O-acetyl amines (see pp. 37 and 49). 

The 2,5-diamino-2,5-dideoxy derivatives of l,4 3,6-dianhydro-D-mannitol and -D-glucitol gave, on deamination, the same product, namely, l,4 3,6-dianhydro-L-iditol, in unspecified yield.176 The product presumably arose from carbonium-ion intermediates, which reacted predominantly with solvent on the less hindered, exo sides of the V-shaped molecule. 

Nevertheless, compound 81 was definitely obtained later by deamination of 2-amino-l,6-anhydro-2-deoxy-j6-D-mannopyranose (103) with nitrous acid, and was identified by reduction to 2,5-anhydro-D-glucitol.366 An analogous deamination was performed with 2-amino-l,6-anhydro-2-deoxy-3-0-tosyl-/l-D-altropyranose to give, after detosylation, 2,5-anhydro-D-allose.361... 

The deamination of the 2,5-diamino-l, 4 3,6-dianhydro-2,5-dideoxy derivatives of L-iditol and of D-glucitol has been observed to yield some 1,4 3,6- dianhydro-L-iditol in each case. The reactions evidently follow the SnI mechanism often observed in deaminations of simple aliphatic amines, and afford the product of the most stable type, with two exo hydroxyl groups. 

The isolation of D-aroWno-hexulose phenylosazone from both 1,4-anhydro-D-mannitol and 1,5-anhydro-D-glucitol indicates that o-aroMno-hexosulose is among the reaction products. - Crude methyl D-glucofurano-sides in dilute sulfuric acid yield pyruvaldehyde, and 2-amino-2-deoxy-D-glucose hydrochloride suffers oxidative deamination. ... 

Deamination of 2-amino-l,5-anhydro-2-deoxy-D-mannitol with nitrous acid gave principally l,5-anhydro-2-deoxy-D-e/ yt/fru-hex-3-ulose (68%), by migration of H-3, and some 2-deoxy-D-a/ a6/no-hexose (8%) and 1,5-anhydro-D-glucitol (6%). It was established that 2-deoxy-D-nrai>//in-hexose is formed via a hydride-shift mechanism, rather than by acid-catalysed hydration of D-glucal produced by an elimination pathway. 

A new, three-step synthesis of 1-deoxy-D-fructose (27% overall yield) is based on reductive desulphurization of 2-amino-2-deoxy-D-glucose diethyl dithioacetal to give 2-amino-l,2-dideoxy-D-glucitol, which was oxidatively deaminated using... 

---