- SYNTHESIS OF 2-DEOXY-D-arabino-HEXITOL AND ITS OXIDATION TO 5-DEOXY-D-threo-HEXULOSE ("5-DEOXY-D-FRUCTOSE") USING IMMOBILIZED CELLS OF Gluconobacter oxydans
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2-Deoxy-D-arabino-hexitol (6) was obtained by borohydride reduction of 2-deoxy-D-arabino-hexose (5).The synthesis of 5, starting from 2,3:4,5-di-O-isopropylidene-D-arabinitol (1), was achieved by one-carbon chain-elongation involving formylation of the Grignard reagent derived from 1-bromo-1-deoxy-2,3:4,5-di-O-isopropylidene-D-arabinitol (2), using lithium formate, followed by hydrolytic removal of the isopropylidene groups.Immobilized cells of Gluconobacter oxydans (ATCC) 15178) selectively oxidized 6 to give 5-deoxy-D-threo-hexulose (7) in 65percent yield (-9percent overall yield from 1).
- Tiwari, Kamal N.,Dhawale, Motiram R.,Szarek, Walter A.,Hay, George W.,Kropinski, Andrew M. B.
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Read Online
- Iridoid glycosides from the leaves of Sambucus ebulus
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Six new iridoid glycosides (1-6) of the "Valeriana type" were isolated from leaves of Sambucus ebulus. The structures were elucidated by 1D- and 2D-NMR spectroscopy, mass spectrometry, and chemical degradation methods as 10-O-acetylpatrinoside-aglycone-11-O-[4″-O-acetyl-α-L- rhamnopyranosyl-(1→2)-β-D-ribohexo-3-ulopyranoside] (1), 7-O-acetylpatrinoside-aglycone-11-O-[4″-O-acetyl-α-L- rhamnopyranosyl-(1→2)-β-D-ribohexo-3-ulopyranoside] (2), 10-O-acetylpatrinoside-aglycone-11-O-[α-L-rhamnopyranosyl-(1→2) -β-D-ribohexo-3-ulopyranoside] (3), patrinoside-aglycone-11-O-[4″-O- acetyl-α-L-rhamnopyranosyl-(1→2)-β-D-ribohexo-3-ulopyranoside] (4), 10-O-acetylpatrinoside-aglycone-11-O-[4″-O-acetyl-α-L- rhamnopyranosyl-(1→2)-β-D-glucopyranoside] (5), and patrinoside-aglycone-11-O-2′-deoxy-β-D-glucopyranoside (6). Compounds 1-4 represent the first examples of acylated iridoid diglycosides bearing the uncommon D-ribohexo-3-ulopyranosyl sugar moiety. Compound 6 is the first iridoid glycoside with a 2-deoxy-D-glucopyranosyl sugar moiety.
- Pieri, Valerio,Schwaiger, Stefan,Ellmerer, Ernst P.,Stuppner, Hermann
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experimental part
p. 1798 - 1803
(2010/03/26)
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- Solvolyses of 2-Deoxy-α- and β-D-Glucopyranosyl 4′-Bromoisoquinolinium Tetrafluoroborates
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The solvolyses of 2-deoxy-α- and β-D-glucopyranosyl 4′-bromoisoquinolinium tetrafluoroborates (1 and 2) were monitored in aqueous methanol, ethanol, trifluoroethanol, and binary mixtures of ethanol and trifluoroethanol. The observed rate constants are consistent with the solvolyses of 1 and 2 proceeding via dissociative (DN * AN) transition states. In comparison to the α-anomer, solvolysis of the β-compound gives a greater transition state charge delocalization onto the ring oxygen atom. Analysis of the solvolysis product ratios indicates that the 2-deoxyglucosyl oxacarbenium ion is not solvent-equilibrated in the solvent mixtures studied. In the solvolysis of compound 1, the solvent trifluoroethanol facilitates diffusional separation of the leaving group and, in so doing, promotes the formation of the retained trifluoroethyl glycoside.
- Zhu, Jiang,Bennet, Andrew J.
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p. 4423 - 4430
(2007/10/03)
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- Acyclic molybdate complexes of aldoses in the arabino and xylo series and their application to the determination of the proportion of acyclic forms in aqueous solution
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Aldoses of the arabino and xylo series with molybdate ions in aqueous acidic medium, form tetradentate acyclic complexes which are much weaker than those of the related alditols.The formation constants (Kf) of these complexes were obtained by two independent methods, potentiometry and UV spectrophotometry, which gave values in good agreement.The structures of the complexes with aldoses were shown by (13)C NMR spectroscopy to involve the ligand in its acyclic form.A study of the complexes of carbohydrate derivatives proved that the magnitude of Kf was mainly dependent on the configuration of the site of chelation.The lower stabilities of the aldose complexes were due to the endergonic opening of the pyranose heterocycle in the first step of the complex formation.An application to the determination of the equilibrium constant for the ring-opening reaction of aldopyranoses is described.It ultimately allowed the calculation of the proportion of acyclic forms (aldehyde and hydrate) in aqueous solutions of the aldoses in the arabino and xylo series.
- Sauvage, Jean-Paul,Chapelle, Stella,Dona, Anne-Marie,Verchere, Jean-Francois
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p. 293 - 306
(2007/10/02)
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- SILYL NITRONATES AND NITRILE OXIDES IN ORGANIC SYNTHESIS. A NOVEL ROUTE TO D,L-DEOXYSUGARS. USE OF ALUMINIUM OXIDE AS SOLID PHASE BASE FOR GENERATION OF NITRILE OXIDES FROM HYDROXIMIC ACID CHLORIDES
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Novel methodology is developed for a three step synthesis of deoxyaldoses and deoxyketoses. 1.Regioselective addition of silyl nitronate or nitrile oxide to a diene. 2.Stereospecific hydroxylation of the double bond. 3.Unmasking of the aldol moiety by catalytic reduction of the 2-isoxazoline.The syntheses of D.L-deoxyribose, D,L-oleose, D,L-digitoxose, D,L-2-deoxygalactose, 1,3-dideoxyfructose, 3-deoxyfructose etc. are described.Basic aluminium oxide is introduced as a solid phase base for the one step synthesis of 2-isoxazolines from aldoximes and olefins.An X-ray diffraction study of compound 13c verifies the stereochemical assignments.
- Torssell, K. B. G.,Hazell, A. C.,Hazell, R. G.
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p. 5569 - 5576
(2007/10/02)
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- 2-DEOXY-D-arabino-HEXOSE, 2-DEOXY-D-lyxo-HEXOSE, AND THEIR (2R)-2-DEUTERIO ANALOGS
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A general method for the synthesis of 2-deoxyhexoses is described. 2-Deoxy-D-arabino-hexose and 2-deoxy-D-lyxo-hexose were prepared from D-glucose and D-galactose, respectively, by a route involving reduction of the respective 4,5-O-isopropylidene ketene diethyl dithioacetals with lithium aluminum hydride, followed by removal of the protecting groups.In agreement with the results of earlier studies with ketene dithioacetals of pentose analogs, reduction of the hexose ketene dithioacetals was found to occur both regio- and stereo-specifically.Reduction with lithium aluminum deuteride gave the (2R)-2-deoxy-2-deuterio-hexoses exclusively.
- Wong, Margaret Y. H.,Gray, Gary R.
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