Tetraacetate 2-amino-2-deoxy

Other tetrahydroimidazoles have been obtained from the reaction of 2-amino-2-deoxyhexoses with isocyanates and with thiocyanates. Thus, 2-amino-2-deoxy-D-glucopyranose hydrochloride (78) reacts readily with phenyl isocyanate to yield77 the corresponding 4,5-D-glucopyrano-l-phenyl-4-imidazolidin-2-one (79). Alternatively, the tetraacetate 80 was converted into the urea derivative 81, the prod-... 

The reaction of 5-amino-5-deoxy-l,2-0-isopropylidene-a-D-xylo-furanose (15) with methanolic hydrogen chloride (0.5 %), under careful exclusion of moisture, results in a mixture of the anomers of methyl 5-amino-5-deoxy-D-xylofuranoside, from which the /8-D anomer crystallizes. The five-membered ring-structure was proved by the results of periodate oxidation and by the infrared spectrum of the tetraacetate, which shows a band for NH. A methyl pyranoside was not found, and 3-pyridinol (21) was formed only in traces. A spontaneous ring-enlargement, such as is observed under similar conditions with 1,2-O-isopropylidene-5-thio-a-D-xylofuranose (see p. 208), is not possible in this instance. Stabilization as the methyl fiiranoside is, apparently, so rapid that the secondary reaction (leading to the pyranose form) does not occur. If water (several percent) is added to the reaction mixture, glycoside formation is hindered, and a large proportion of 3-pyridinol is formed. ... 

The reaction, under the same conditions, has been extended to other /3-keto esters. Ethyl 3-oxovalerate, ethyl 3-oxohexanoate, and diethyl 3-oxoglutarate react with 2-amino-2-deoxy-D-glucose to give compounds (11), (12), and (13), respectively, whose oxidations with lead tetraacetate or periodic acid furnish the corresponding aldehydes (14), (IS), and (16). 

Animal studies have shown that in vivo F MRS can be used in metabolic studies. It has been shown that 3-fluoro-3-deoxy-D-glucose in the brain is metabolized primarily in the aldose reductase sorbitol pathway, suggesting that F MRS may be a useful tool for the further elucidation of this pathway. Further studies have shown that it is also possible to study the metabolism of fluorinated galactose, tryptophan and protein in vivo and determine intracellular calcium levels. The concentration of this cation was shown to be the same in the kidney, spleen and brain of rats, at approximately 200 nM. These measurements were obtained by infusing the calcium indicator 5F-BAPTA (=5,5-difluoro-l,2-bis(o-amino-phenoxy)ethane-N, N, M, A/ -tetraacetic acid) intravenously or intraventricularly into the animal, and so the potential application to human subjects appears limited. 

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