Allose 1,6-anhydro

The potentialities of this method are such that, with the proper choice of hexofuranose derivative, access can be gained to 2,5-anhydroaldoses in which the side chains have the cis orientation, as would be required for further elaboration into C-nucleosides. Matsui and coworkers62 reported the synthesis of modified C-nucleosides by acidic treatment of 3-0-benzyl-l,2-0-isopropylidene-5,6-di-0-(methylsulfonyl)-/3-L-talofuranose (60), to give 2,5-anhydro-3-0-benzyl-6-0-(methylsulfonyl)-aidehydo-D-allose dimethyl acetal (61). 

Another method of synthesis of derivatives of 3-methyl-D-glucose lies in the scission of the anhydro-ring of 2,3-anhydro-D-allose derivatives with sodium methoxide, when the entry of the methoxyl group is accompanied by a Walden inversion on C3.82... 

Carbohydrates.—The acid (87), an intermediate in the synthesis of oxaprostaglandin derivatives from D-ribofuranose sugars,84 is obtained from the aldehyde (88) and the sodium salt of (79). The condensation of 2,5-anhydro-D-allose derivatives with (89) gave the expected products (90).85 Similarly, 1,4-furanoses (91) afford (92).86 These unsaturated halides are useful intermediates for further modifications. 

In their pioneering work. Just and co-workers have described many interesting transformations of the Diels-Alder adducts of furan to methyl nitroacrylate (77 + 77 ) and to dimethyl acetylenedicarboxylate (53). The mixture of racemic adducts 77 + 77 was hydroxylated into the exo-cis-diols 125 + 125 , separable by crystallization. Treatment of the isopropylidene acetal obtained from 125 with diazabicyclo[5.4.0]undec-5-ene (DBU) gave a high yield of alkene 126. Ozonolysis followed by a reductive work-up with dimethylsulfide, then with NaBH4, gave a mixture of epimeric triols 127. Cleavage with sodium periodate afforded 2,5-anhydro-3,4-0-isopropylidene-DL-allose (128) in 15 % yield, based on methyl 2-nitroacrylate used. TTie same allose derivative was obtained from adduct 53. ... 

The formation in low yield of 3,6-anhydro-4,5-0-isopropylidene-D-allose dimethyl acetal (82), together with methyl 3-O-p-tolylsulfonyl-D-glucopyranoside (83) as the main product, by the action of boiling 2% methanolic hydrochloric acid (under reflux for 27 hours) on 1,2 5,6-di-O-isopropylidene-3-O-p-tolylsulfonyl-a-D-glucofuranose (81) has been reported.87... 

Fusion of an oxirane ring to a pyranose ring also deforms it, and thereby lowers its stability. The composition of 2,3-anhydro-D-mannose in aqueous solution,165 as determined by g.l.c. of the trimethylsilyl derivatives, is 23 7 65 5. This is remarkably similar to the composition of a solution of 2,3-O-isopropylidene-L-rhamnose. For 2,3-anhydro-D-allose, the ratios are166 41 12 5 42 (or 41 5 12 42). In this case, although the proportion of furanose forms is substantial, there is no clear preponderance of the //-furanose form, presumably because OH-1 and OH-2 are trans but OH-1 is quasi-equatorial by contrast, in the (preponderant)... 

Nevertheless, compound 81 was definitely obtained later by deamination of 2-amino-l,6-anhydro-2-deoxy-j6-D-mannopyranose (103) with nitrous acid, and was identified by reduction to 2,5-anhydro-D-glucitol.366 An analogous deamination was performed with 2-amino-l,6-anhydro-2-deoxy-3-0-tosyl-/l-D-altropyranose to give, after detosylation, 2,5-anhydro-D-allose.361... 

M. Cerny, J. Stanek, Jr., and J. Pacak, Syntheses with anhydro sugars. 7. Preparation of 4-deoxy-D-rifto-hexose (4-deoxy-D-allose), 4-deoxy-D-(yvo-hexose (4-deoxy-D-mannose) and of their 1,6-anhydro derivatives, Collect. Czech. Chem. Commun., 34 (1969) 1750-1765. 

J. G. Buchanan, D. M. Clode, and N. Vethaviyasar, Potential hexokinase inhibitors. Synthesis and properties of 2,3-anhydro-D-allose, 2,3-anhydro-D-ribose, and 2-0-methylsulphonyl-D-mannose, J. Chem. Soc., Perkin Trans. 1, (1976) 1449-1453. 

T. Uryu, K. Kitano, and K. Matsuzaki, Ring-opening polymerization of 5,6-anhydro-glucose and 5,6-anhydro-allose derivatives. Effect of substitution or configurational difference at the position of sugar monomers on polymerization behavior, J. Polym. Sci., Part A Polym. Chem., 20 (1982) 2181-2194. 

Fig. 2. Topographies of hexameric non-glucose cyclooligosaccharides composed of D-mannose (83), D-allose (84) and 2,3-anhydro-D-mannose units (55) in an a-(l—>4)-link-up each.

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