Glucose with morpholine

Further expanding upon the effects bases have on sugars, the Amadori rearrangement incorporates new nitrogen functionalities with the generation of a ketose derivative. Scheme 6.82 illustrates this reaction applied to the combination of glucose with morpholine... 

A kinetic analysis of the Amadori reaction of glucose with morpholine has been reported, and a study that provides further evidence for the reversibility of the Amadori reaction is covered in Chapter 9 (Section 3.8). 

Pyrazine has also been prepared by decarboxylation of 2-carboxypyrazine (564), 23-dicarboxypyrazine (397, 564), 2,5-dicarboxypyrazine (22, 272, 564, 565), 23>5-tricarboxypyrazine, and tetracarboxypyrazine (564). It is also produced on heating glucose with 25% aqueous ammonia at 100° (33), on heating 2,6-dioxo-morpholine with hydrazine or hydroxylamine in hydrochloric acid solution, and on heating morpholylsemicarbazide with 20% hydrochloric acid (28). 

Secondary amines and amino acids react in an entirely different way. Indeed, L-proline forms a mixture of the four possible tautomers, but, after a time, ninhydrin-positive substances may be formed by breakdown of the proUne molecule. (Other ketoses do not give this reaction.) Secondary amines, such as piperidine, will not react at 0°, but, at higher temperatures (40-60°), some D-fructosylamine is formed, together with a higher proportion of D-glucose by isomerization. Morpholine or dicyclohexylamine give a 20 to 25% yield of D-n6o-hexulose, and may be used on a preparative... 

Starch reacts with isocyanates to produce carbamates (urethanes), which are esters of carbamic acid. Several reactions of starch with phenyl-, various aryl-, 1-naphthyl-isocyanates or 1,6-hexamethylene- and 2,4-tolyl-diisocyanates were conducted either in pyridine or morpholine below the boiling point of these solvents.2546-2548 In each case all three hydroxyl groups of the glucose units reacted to give tricarbanilates, provided a sufficient amount of the isocyanate reagent was used. 

The chemical synthesis of uridine 5-(a-D-glucopyranosyl pyrophosphate) has been effected by condensing a-n-glucopyranosyl phosphate with uridine 5-phosphate in the presence of dicyclohexylcarbodiimide. The yield of glycosyl nucleotide in this reaction is very low, primarily because dicyclohexylcarbodiimide promotes the formation of n-glucose cyclic 1,2-phosphate in preference to the formation of the pyrophosphate bond. In an improved synthetic method, the nucleotide is first converted to a phosphoramidate (5) or phosphoromorpholidate (6), by condensation in the presence of dicyclohexylcarbodiimide with ammonia or morpholine, respectively. 

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