Svein Morgenlie

Gas chromatography-mass spectrometry of hexuloses and pentuloses as their O-isopropylidene derivatives: analysis of product mixtures from triose aldol-condensations

Identification and quantitation of hexuloses and pentuloses in mixtures has been achieved by gas chromatography-mass spectrometry of their O-isopropylidene derivatives. The method has been applied to product mixtures from triose aldol-condensations. The use of strongly basic anion-exchange resins as catalysts in the aldol condensation gives considerably higher proportions of fructose than when alkali or alkaline-earth hydroxides are applied.

Reaction of some aldoses with anhydrous cupric sulphate-acetone: preparation of 3,4-O-isopropylidene derivatives

Abstract 3,4-O-isopropylidene derivatives are obtained in yields of 40–60% when D -fucose and 6-O-methyl- D -galactose are treated with acetone and anhydrous cupric sulphate. 3,4-O-Isopropylidene-D-ribose is isolated in 15–20% yield after treatment of the parent aldose with the same reagent, whereas 4,6-O-isopropylidene-D-glucose is formed in low yield from D-glucose in the presence of N,N-dimethylformamide.

Base catalysed isomerisation of aldoses of the arabino and lyxo series in the presence of aluminate

Base-catalysed isomerisation of aldoses of the arabino and lyxo series in aluminate solution has been investigated. L-Arabinose and D-galactose give L-erythro-2-pentulose (L-ribulose) and D-lyxo-2-hexulose (D-tagatose), respectively, in good yields, whereas lower reactivity is observed for 6-deoxy-D-galactose (D-fucose). From D-lyxose, D-mannose and 6-deoxy-L-mannose (L-rhamnose) are obtained mixtures of ketoses and C-2 epimeric aldoses. Small amounts of the 3-epimers of the ketoses were also formed. 6-Deoxy-L-arabino-2-hexulose (6-deoxy-L-fructose) and 6-deoxy-L-glucose (L-quinovose) were formed in low yields from 6-deoxy-L-mannose and isolated as their O-isopropylidene derivatives. Explanations of the differences in reactivity and course of the reaction have been suggested on the basis of steric effects.

Oxidation of 1,2-O-isopropylidenealdohexofuranoses with silver carbonate on celite

Abstract 1,2-O-Isopropylidenealdohexofuranoses are oxidized by silver carbonate-Celite in boiling methanol to methyl 1,2-O-isopropylidenepentofuranuronates. 1,2-O-Isopropylidenepentodialdo-1,4-furanoses are intermediates, and various amounts of esters of 1,2-O-isopropylidenehexofuranuronic acids are formed as side products. The site of initial oxidation depends on the configuration of the 1,2-O-isopropylidenehexose. The results are discussed on the basis of adsorption involving HO-3, HO-5, and HO-6 prior to oxidation.

Synthesis of 3-hexuloses from 1,2:5,6-di-O-isopropylidenehexitols.

A simple, but low-yielding method for the synthesis of 3-hexuloses has been elaborated. Oxidation of 1,2:5,6-di-O-isopropylidenehexitols with bromine in the presence of barium carbonate, followed by mild-acid hydrolysis of the oxidation products gave the free hexuloses. Oxidation occurred at only one of the carbon atoms bearing free hydroxyl groups. From the D-mannitol derivative, D-arabino-3-hexulose was obtained via the di-O-isopropylidene derivative, whereas the D-glucitol derivative gave a mixture of the 1,2:5,6-di-O-isoprpylidene derivatives of L-xylo- and D-ribo-3-hexulose, separable by column chromatography. Mild-acid hydrolysis of the oxidation products afforded the free hexuloses.

Analysis of mixtures of some mono-O-methylaldoses with the common aldoses by g.l.c.-m.s. after isopropylidenation

Abstract The O-isopropylidene derivatives of seven naturally occurring mono-O-methylaldoses have been characterised by g.l.c.-m.s. G.l.c. conditions have been found under which almost complete separation of the O-methyl sugars and the common aldoses as their O-isopropylidene derivatives can be achieved. This analysis procedure has been applied to the hydrolysates of three polysaccharides that contain O-methyl sugars.