Carbon deoxy sugars

Write the open-chain structure of a four-carbon deoxy sugar. 

The maciocyclic lactone of all avermectins has an a-L-oleandtosyl-a-L-oleanchosyloxy substituent at carbon 13, which is a 2-deoxy sugar glycoside. 

The 3-deoxy 1,2-O-isopropylidene D-gluco- (37) and D-galacto-furanoses (17) have been used (53, 58) in yet another way to prepare deoxy sugars phosphorylated in the terminal position. If either of these compounds is treated with one molar equivalent of periodate, carbon 6... 

The 3-deoxy pentose phosphates (44 and 45) can be further degraded to phosphorylated deoxy sugars (58) treatment of either of them with periodate will cleave the carbon-carbon bond between Ci and C2 to yield 2-deoxy-n- (46) and -L-gZycero-tetrose-4-phosphates (47). 

However, when we oxidized malonaldehyde (56) in the conditions just described for triose reductone, although formic acid and carbon dioxide were produced in high yields, the periodate consumption was erratic. Similar results were obtained with deoxy sugars. This discrepancy may be caused by the incomplete enolization of the first intermediate, hydroxy malonaldehyde —i.e. tartronic dialdehyde (5,22,32), to triose reductone, or may concern the hydroxylation step itself. 

Despite several attractive features in this method of direct halogen introduction and the obvious applications in the synthesis of deoxy sugars, its uses have not been further exploited by other groups of workers. Some new related methods have become available which reportedly eliminate the difficulties previously encountered such as rearrangement, unreactivity due to steric hindrance, and phosphonate ester formation. The reaction is based on the observation (28) that triethylphosphine reacts with ethanol and carbon tetrachloride to give ethyl chloride, chloroform, and triethylphosphite. In a new adaptation (76, 77) of this... 

Five peaks are important in the mass spectra of the dialkyl dithioacetals of the deoxy sugars 6 (as well as of the common pentoses and hexoses). These are fragments A, B, and C, the dithioacetal portion [CH(SR)2] resulting from C-l, and the remaining portion of the molecule [M — (CH(SR)j) ]. They result from carbon-carbon bond-cleavage on electron impact, with the production of charged and neutral fragments. 

The preparation of (71) is given in the following experiment, which serves to typify the synthesis of a 2-deoxycardenolide, starting with a 2-deoxy sugar. The experiment also embodies a Meystre-Miescher type of azeotropic distillation technique for removing the water, and saponificar tion catalyzed by potassium hydrogen carbonate for isolation of the unsubstituted cardenolide. 

Photolysis of iodosugars in alcohol solution is of great interest to obtain deoxy sugars, but in the presence of tri-n-butyltin hydride and poor electron alkenes, equatorial carbon-carbon bonds are obtained with a high stereoselectivity at C-4 position [39] from 29 forming mainly 30. 

Mycaminose has been found as a component of carbomycin (Magna-mycin)83 and, structurally, it resembles desosamine84 (see Table II). On periodate oxidation, one carbon atom is split out, to yield a seven-carbon amino sugar the results of subsequent reaction with the oxidant indicated the presence of a hydroxyl group at C4. Alkaline deamination of the seven-carbon sugar proceeded at a rate similar to that of 2-amino-2-deoxy-D-glucose, whereas mycaminose itself reacted far more rapidly this indicates the dimethylamino group to be at C3. Mycaminose is believed to be 3,6-dideoxy-3-dimethylamino-/3-D-altrose.84a... 

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