Hexulose 6-deoxy

Escherichia coli, adapted to grow on L-rhamnose, will convert this sugar to 6-deoxy-L-am6mo-hexulose ( L-rhamnoketose ). In the presence of ATP, dialyzed aqueous extracts of these cells will phosphorylate this... 

Treatment of 3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-erythro-hex-3-enofuranose with iodine and thallous fluoride in anhydrous ether afforded227 3-deoxy-l-fluoro-3-iodo-l,2 5,6-di-0-isopropyli-dene-D-xy/o-4-hexulose in 80% yield, together with small proportions of (tentatively identified) 3-deoxy-4-fluoro-3-iodo-l,2 5,6-di-0-iso-propylidene-a-D-allofuranose and two unidentified products. A mechanism proposed for the furanose ring-opening involves the formation of a 3,4-iodonium ion, and attack by fluoride at C-l. 

On deamination, 2-amino-l,5-anhydro-2-deoxy-l>mannitol gave l,5-anhydro-2-deoxy-D-eryf/iro-3-hexulose as the major product.54 The substitution product 1,5-anhydro-D-glucitol was formed to a small extent, and inversion again predominated, as with other axial amines (60, 72, and methyl 4-amino-4-deoxy-a-D-galactopyranoside) this is in accord with the predominant inversion of configuration reported for deamination, in water-rich media, of simple cyclohexyla-mines,154 and aminodecahydronaphthalenes39 in which the amino group is axial. As discussed previously (see p. 15), the extent of inversion can vary considerably with the nature of the solvent, and steric factors appear to be important in deaminations of per-O-acetyl amines (see pp. 37 and 49). 

The composition of aqueous solutions of all of the 2-hexuloses, of several 3-hexuloses, 2-pentuloses, and their deoxy derivatives, and some of the hexulosonic acids is shown in Table IV. 

Deoxyketoses are of rare natural occurrence. The antibiotic hygromycin177 has been shown to contain 6-deoxy-D-arabmo-hexos-a-ulose residues, since reduction of the free sugar gave 6-deoxy-D-altrose and L-fucose. Yungsten and coworkers171 reported the isolation of a 6-deoxy-L-x2/io-hexulose (an-gustose) from the antibiotic Angustmycin A, for which structure (37) was proposed. 

Deoxy-D-xyZo-hexose 4-Deoxy-D-erytliro-pentose 4- Deoxy-D-erytAro-hexulose 0.17(133) 0.53 (131) 0.28(132)... 

Guanosine D-Mannose G DP-6-deoxy-D-ly xo-4-hexulose (4-keto-6-deoxy-D-man nose)... 

Cytidine D-Glucose CDP-6-deoxy-D-xylo-4-hexulose (4-keto-6-deoxy-glucose) 6-Deoxy Amino Sugars... 

TDP-D-glucose is initially attacked by enzyme-NAD+ (enzyme protein containing one mole of firmly bound NAD+) at carbon 4 to yield TDP-D-xylo-4-hexulose and accompanying formation of enzyme NADH. The 4-ulose rearranges by / -elimination of water between carbons 5 and 6 to form an unsaturated glucoseen. This unsaturated 5,6-glucoseen serves as hydrogen acceptor for enzyme-NADH to restore enzyme-NAD+ and leads to the end product of the reaction TDP-6-deoxy-D-xylo-4-hexulose. 

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