Sugar carbonates, formation

BeO mixed with half its weight of sugar carbon and a little oil and heated in an electric furnace for 8-10 minutes with 950 amperes at 40 volts. Obtained carbide whi< h he calls Be Cs (which was undoubtedly BejC) in crystals, harder than quartz, transparent. Specific gravity 1.9 at 15°. Attacked at red heat by Cl, Br, HF, and HCl with liberation of carbon and formation of halide. Slowly decomposed water, liberating CH. Quickly decomposed by caustic alkalies. No other carbide seems to exist. 

Syringolide 2 (58), a bacterial signal molecule that elicits active defence in resistant plants, has been made (Scheme 11) from the protected ketose 57, itself prepared from D-arabinose (sugar carbons numbered) in nine steps. This sequence can be considerably shortened by use of a chemo-enzymatic approach, in which 57 was made in three steps by condensation of dihydroxyacetone phosphate with 0-Pmb-glycolaldehyde, catalysed by fructose 1,6-diphosphate aldolase, followed by action of phosphatase and formation of the isopropylidene derivative. ... 

In a new formal synthesis of (-h)-thienamycin (Scheme 29), the 6-deoxy-glucosamine derivative 142 underwent base-catalysed rearrangement (see Vol. 16, p. 149), followed by oxidation, to give the separable isomers of 143. Both of these could be transformed, by sequences involving base-catalysed epimeriz-ation, into the same all-frans-lactone 144. Formation of a p-lactam and then oxidation by lead tetraacetate gave 145 (original sugar carbons indicated), which is an intermediate in a previous route to thienamycin. ... 

The tricyclic structure (48), constituting the ABC ring framework of brevetoxin B has been prepared in chired form from tri-0-acetyl-D-glucal,44 and the UK substructure (49) of the same major target has been synthesized from penta-O-acetyl-D-mannopyranose.45 in both sequences, the first step involved formation of a C-glycoside by reaction with allyl-trimethylsilane sugar carbons are numbered. 

Certain aliphatic compounds are oxidised by concentrated nitric acid, the carbon atoms being split off in pairs, with the formation of oxalic acid. This disruptive oxidation is shown by many carbohydrates, e.g., cane sugar, where the chains of secondary alcohol groups, -CH(OH)-CH(OH)-CH(OH)CH(OH)-, present in the molecule break down particularly readily to give oxalic acid. 

Now since the configuration of carbon atoms 3, 4 and 5 of glucose and fructose art identical, it folhjws that glucosazone and fructosazone are identical in all respects. The osazone is formed however more rapidly from fructose than from glucose, and this difference in rate of formation may be used to distinguish the two sugars, provided the reactions are carried out under strictly parallel conditions (pp. 138, 338). 

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