Reversible Conversion of Amino- into Anhydro-sugars

ANHYDRO-SUGARS have already been the subject of diligent study by several groups of workers, and the chief methods of obtaining these compounds have been through the hydrolysis of sulphonic or halogen acid esters of sugar derivatives. For example, 2: 3-anhydro?-methyltaloside was obtained by alkaline hydrolysis of 2-p-toluene sulphonyl?-methylgalactoside1; 1: 6-2: 3-dianhydro?-talose was isolated after the alkaline hydrolysis of 2-mesyl 1: 6-anhydro?galactose2, and 3: 6-anhydro?-methylglucoside has been obtained by the hydrolysis of 6-bromo?-methylglucoside3. Sulphuric acid esters of sugars have also been made to yield anhydro-derivatives. For example, Duff and Percival4 obtained 3:6-anhydro?-methyl glucopyranoside from barium -methyl glucopyranoside sulphate. Finally, the same type of reaction has been applied to the nitric acid esters of sugars. Gladding and Purves5 obtained a product which probably contained 2: 3-anhydro?-methyl-mannoside from 3:4: 6-triacetyl?-methylglucoaide 2-nitrate and 3: 6-anhydro?-methyl-glucoside from 2: 3: 4-triacetyl?-methylglucoside 6-nitrate.