6-Deoxyhexoses synthesis

Conversely, fraction II alone did not catalyze net synthesis of 6-deoxyhexose. Thus, fraction I and II were not cross contaminated since no 6-deoxyhexose synthesis was observed in the absence of either. These observations are consistent with the following reaction sequence ... 

The more-common 2-acetamido-2-deoxyhexoses have not been found as thymidine 5 -pyrophosphate derivatives. Nevertheless, the enzymic synthesis of thymidine 5 -(2-acetamido-2-deoxy-a-D-gluco-pyranosyl pyrophosphate) and -(2-acetamido-2-deoxy-a-D-galactopy-ranosyl pyrophosphate) has been achieved with enzyme preparations from Pseudomonas aeruginosa,116 Azotobacter vinelandii,52 and gastric mucosa.117... 

This interesting transformation from a readily available 6-deoxyhexose forms the basis for the synthesis231 of 6-deoxy-2,3-di-0-methyl-D-allose (mycinose),168 one of the carbohydrate moieties of the antibiotic chalco-mycin. The synthesis merely involves the protection of the C-5 hydroxyl group in (41) by benzylation, followed by partial hydrolysis with acid, methylation of the product at the C-2 and C-3 hydroxyl groups, and debenzylation. 

Another strategy for the synthesis of 5-deoxyhexoses involves the anti-Markovnikov hydration of a 5,6-alkene derivative, as first developed by Wolfrom.97,100 Since that report, the same approach has been followed by several authors, and conditions for the key step have been improved. For example, starting from tosylate 43, treatment with sodium iodide resulted in the alkene 44. Addition of iodine trifluoracetate (produced in situ by the reaction of silver trifluoroacetate and iodine) to 44, followed by hydrogenation over... 

A powerful example of the use of conjugated enones in the synthesis of 2,4-difunctionalized compounds, such as 2,4-diamino-2,3,4,6-tetra-deoxyhexoses of the kind found in several antibiotics, is illustrated by... 

For the synthesis of oligosaccharide units containing residues of configurationally accessible 6-deoxyhexoses, standard protecting-groups methodology has... 

Sharma, M, Korytnyk, W, A general and convenient method for synthesis of 6-fluoro-6-deoxyhexoses, Tetrahedron Lett., 18, 573-576, 1977. 

An alternative method for synthesis of the 1,6-anhydrides of amino-deoxyhexoses consists in cleavage of the oxirane ring by azide ions in aqueous ethanol or 2-ethoxyethanol in the presence of ammonium chloride as a buffer379-537-539 740-741-750-751 (see also, Ref. 45a). The azido-hydrins thus formed are reduced by nascent hydrogen (from, for example, zinc and hydrochloric acid), or catalytically in the presence of platinum, palladium, or Raney nickel, to give the corresponding amino derivatives. 

---