1,2-Dideoxy-3-heptuloses

Substitution was also the major reaction in the deamination of l-amino-2,6-anhydro-l-deoxy-D-allitol 67and l-amino-2,6-anhydro-l,7-dideoxy-L-g(i/cero-L-ga(acfo-heptitol.168 The rearrangement product, a l,6-dideoxy-2-heptulose, was also isolated from the latter amine, the ratio of substitution to rearrangement being 1.6 1. 

Two biologically important ketoaldonic acids should be mentioned here. N-Acetylneuraminic acid (5-acetamido-3,5-dideoxy-D-gh/cero-D-gaiocto-nonulosonic acid) is homomorphous with 3-deoxy-g(uco(and monno)-heptulose, and therefore, in solution, would be expected to be overwhelmingly in the / -D -pyranose form (14). Actually, although the... 

The composition of the four l,2-dideoxy-3-heptuloses has been determined.32 These compounds are similar to the hexuloses, the hydroxyl group on C-1 having been replaced by a methyl group their composition should be similar to those of the corresponding hexuloses, and, in most cases, this is true. For 1,2-dideoxy-3-/yxo-heptulose, however, and for its lower homolog, 1-deoxytagatose, the a-furanose form (in which 03 and the side chain are cis) is more stable than the / - furanose (with 02 and 03 cis). A study of the conformations can rationalize this observation in the / -furanose, there is a quasi-syn-axial interaction between 0-2 and 04 which is aggravated by the side chain, particularly if bulky. There is a similar effect in the / -pyranose, which also becomes a minor constituent of the equilibrium mixture. 

Treatment of 2-deoxy-3,4 5,6-di-O-isopropylidene-D-arahtno-hex-ose diethyl dithioacetal (128a) with butyllithium in tetrahydrofuran produced a carbanion that is stable by virtue of having no electronegative substituent at C-2 this anion subsequently reacted with iodo-methane to afford255" l,3-dideoxy-4,5 6,7-di-O-isopropylidene-D-arabino-heptulose diethyl dithioacetal (128b) in 82% yield (see Section 11,5). This reaction provides a useful route to 1,3-dideoxy-2-ketoses. 

Alkylation of 2-deoxy-3,4 5,6-di-0-isopropylidene-D-crfli>mo-hexose diethyl dithioacetal at C-1 with butyl lithium-methyl iodide afforded the corresponding derivative of 1, S-dideoxy-D-craftwo-heptulose. ... 

Deoxy, 5,7-0-benzylidene 2,6-Anhydro-5,7-0-benzylidene-l,3-dideoxy-D-SLtahi-no-4-heptulose [66149-65-3]... 

Dianhydro-l-deoxy-4-0-mesyl-D-glucitol, D-492 2,5 3,6-Dianhydro-l-deoxy-4-0-tosyl-D-glucitol, D-492 1,2 3,4-Di-0 -benzylidene-5-deoxy-D-arabinitol, D-40 l,2-Dideoxy-am6mo-hexitol Y>-form, D-595 i>-erythro iorm, T-176 moM K) 2-Heptulose D-form 1-Deoxy, H-62 Methyl l-deoxy-D-r/6o-2-hexulopyranoside, D-222... 

Azido-sugars are frequently prepared by reaction of epoxides with azide ion. 3-Azido-3-deoxy-L-threose 68 was synthesized from cu-but-2-ene-l,4-diol 66 via the Sharpless asymmetic epoxidation product 67, and was converted into 6-azido-6-deoxy-L-galocro-heptulose 69 by an enzyme-catalyzed aldol condensation (Scheme 13). 3-Azido-3-deoxy-L-etythrose, and thence 6-azido-6-deoxy-L-g/uco-heptulose were obtained in a similar way via 4-rerf-butyldiphenylsilyoxy-rraiu-but-2-enal. These and two other azido-heptulose isomers made from the enantiomeric 3-azido-3-deoxy-tetroses, were converted to a- and P-l-homonojirimycin and homomannonojirimycin on hydrogenation. Ethyl 3-azido-2,3-dideoxy-D-eryr/iro-pentopyranoside and its 3-C-methyl analogue 71, R=H or Me, were synthesized from crotonaldehyde or 3-methyl-2-... 

Standard procedures have been used to convert the 2,3-unsaturated heptonic acid (209) (prepared from 3,4,5,6,7-penta-0-acetyl-l-deoxy-I-diazo-D- / co-heptulose) into 5,6,7-tri-0-acetyl-2,3-dideoxy-D-nra6mo-heptofuranose (210),... 

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