Pentoses 2-amino-2-deoxy-, synthesis

The furoisoxazoline (8) has been used for the total synthesis of amino-deoxy pentose and pentitol derivatives, synthesis of the latter being outlined in Scheme 5. ... 

The well-known cytoplasmic shikimate pathway is important to aromatic amino acid synthesis. It takes a long metabolic pathway to reach to an aromatic amino acid from D-glucose. Two metabolic intermediates, phosphoenolpymvate from the glycolytic pathway and D-erythrose-4-phosphate from the pentose-phosphate pathway, must combine to form 3-deoxy-7-phospho-D-arabinoheptulosonate before formation of 3-dehydroquinate (Fig. 13.4). Thus, there are still several barriers difficult to overcome in the already existing technologies of shikimate fermentation from D-glucose (Draths et al. 1999). 

Mode of synthesis A. cyanohydrin, by way of 2-nmino-2-deoxy-aldonic acid B. scission of sugar derivative epoxide with ammonia C. interconversion of hexosamine series D. hemihydrogenation of a-amino nitrile466 E. rearrangement of ketosyl-amine F. Removal of last carbon atom of hexosamine G. Hydrazinolysis (with inversion) of 2-0-tosyl-pentose. 6 Physical constants taken from this reference. c Derivatives (only) isolated. 

Extension and elaboration of the original nitromethane work continued to occupy the attention of Sowden and his collaborators until his death. A convenient synthesis of 2-deoxy-D-er2/f/tro-pentose was a particularly noteworthy achievement, and the substitution of 2-nitroethanol for nitromethane opened the door to the ketoses. The addition of sodium meth-oxide or ammonia to C-nitro-olefins also provided convenient means for preparing 2-0-methyl derivatives and 2-amino sugars, respectively. 

It is known that deamination of some readily available amino acids can be performed with nearly quantitative retention of configuration. Based on this conversion, Yamada and co-workers elaborated an ingenious synthesis of o-ribose and D-lyxose starting from L-glutamic acid. The preliminary communication of this work was reported in the first volume of Ais series.Now the full details have been published. In an extension of the application of the unsaturated intermediate (399) for the synthesis of other pentoses, all 2,3-anhydro derivatives (400-403) were prepared. LAH-Reduction of -D-ribo and o-D-lyxo epoxides (400 and 401) afforded, after acetylation, 3-deoxy-pentosides 404 and 405, whereas the same reaction conditions converted fi-D-lyxo a-D-ribo epoxides (402 and 403) into the corresponding 2-deoxy-derivatives (406 and 407). 

Condensation of syn- or anti-27 with hydrazine afforded new pyrazole derivatives 28 with a stereodefined and protected amino diol side chain [64]. The preparation of push-pull substituted unsaturated monosaccharide derivatives and their use in the synthesis of nucleoside analogs have been reviewed [65]. Thus, the 2-formyl pentose glycals were transformed to the corresponding acyclo-C-nucleosides 29 [66]. Similarly, the benzy-lated 2-formylglycals reacted with hydrazine derivatives to afford the substituted l,2,4-tri-0-benzyl-lC-(lH-pyrazol-4-yl)-D-tetritols the deprotection of which was achieved with Pd/H2 to yield the lC-( 1-methyl-lH-pyrazol-4-yl)-D-tetritols [67]. 3-0-Benzyl-6-deoxy-l,2-0-isopropylidene-o -D-xylo-hept-5-ulofuranurono-nitrile was reacted with f, N-dimethylformamide dimethyl-acetal in THF to furnish the (E)-3-0-benzyl-6-deoxy-6-dimethyl-aminometh-ylene-l,2-0-isopropylidene-Q -D-xylo-hept-5-ulofuranurono-nitrile as a major product, and on treatment with carbon disulfide and methyl iodide under basic conditions afforded 3-0-benzyl-6-deoxy-l,2-0-isopropylidene-6-[bis(methylsulfanyl)methylene]-a-D-xylo-hept-5-ulofuranurono-nitrile. Further reaction with hydrazines yielded the reversed pyrazole-C-nucleoside analogs [68]. 

The oxidation of aldose phenylosazones to aldos-2-uloses (osones) and the g.l.c. separation of the TMS ethers of the products have been examined in the cases of the D-f/ reo-pentose, D-arabino-, D-lyxo-, L-xy/o-hexose compounds, and two disaccharide derivatives. A new approach to the synthesis of ketonic carbohydrate derivatives involves the treatment of amino-compounds with sterically hindered quinones to prepare imines which rearrange as shown in Scheme 1 to give products which undergo hydrolysis to ketones. The method gave the 2- and 3-ulosides, respectively, when applied to methyl 2-amino-2-deoxy-a- and 3-D-glucopyranoside and methyl 3-amino-3-deoxy-j3-D-allo-furanoside. ... 

The metabolic-synthesis of 4-amino sugars is widespread in the microorganisms and takes place via CDP-sugars. In many cases the sugars involved are 6-deoxy hexoses (i.e. C-methyl pentoses) and again the initial formation of a 4-oxo-sugar intermediate is required. The formation of 6-deoxy-4-oxo-sugars is discussed below. 

Non- oxidative branch Pentose-5 -Phosphates Ribose-5-P 2 deoxy ribose-5-P 5 -phosphoribosyl-1 -pyrophosphate (PRPP) i) Structural components of nucleotides a. Basal structural component of RNA b. Basal structural component of DNA c. Precursor of both de novo and salvage synthesis of nucleotides ii) Intermediate products of purine metabolism and act as precursor molecules of cofactors, e g., riboflavin, flavin mononucleotide (FMN), flavin adenine di nucleotide (FAD) iii) Precursor of the amino acid. Histidine. 

---