Shozaburo Kitaoka

Oxidative cleavages of 1,2-diaminosugars and their significance in the mechanism of the amino-carbonyl reactions.

N-Benzyl-(l-deoxy-l-p-toluidino)-D-fructosylamine gives extensive browning on heating in methanol or ethyl acetate especially in the present acid, and from the browned solutions N-benzyl-D-arabinonamide has been isolated. Under stream of oxygen the browning is less extensive but the yield of D-arabinonamide is increased; under nitrogen the browning is slight and unchanged diaminosugar has been recovered. In the presence of an excess of benzyl-amine, benzylammonium D-arabinonate has been isolated. N-Cyelohexyl- (2-cyclohexylamino-2-deoxy) -D-glucosylamine on heating with acid in stream of oxygen gives small amounts of N, N-bis (cyclohexyl) -oxaldiamide, dicyclohexyliminoglyoxal and cyclohexylammonium D-arabinonate as the oxidation products. The mechanism of the oxidative cleavages has been explained in terms of the high reducing ability of the enediamine structures which are formed by rearrangement of 1,2-diaminosugars; in the case of N-cyclohexyl- (2-cyclohexylamino-2-deoxy) -D-glucosylamine dehydrogenati...

Sialic Acids and Related Substances:Part I. Reaction of N-Acetyl-D-galactosamine and Oxalacetic Acid

N-Acetyl-D-galactosamine, N-acetyl-D-mannosamine and N-acetyl-D-glucosamine were allowed to react with oxalacetic acid under alkaline conditions, and the condensation products purified by ion-exchange chromatography. Properties of these products on the whole are similar to each other, though there is a minor but significant diference in the condensation product with N-acetyl-D-galactosaminc. Paper chromatograms of the condensation products suggest that N-acetyl-D-galactosamine as well as N-acetyl-D-glucosamine are epimerized partly before they condense with oxalacetic acid to givc each two sialic acids with different configurations at C-5 from each other.