- Method for producing optically active alcohols
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The invention relates to a process for the preparation of optically active alcohols from optically active carboxylic acids by reducing an optically active carboxylic acid with hydrogen in the presence of a catalyst comprising ruthenium and at least one further metal or transition metal having an atomic number in the range of from 23 to 82.
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- A highly diastereoselective synthesis of 4-octulose and 2-deoxy-4-octulose from a D-fructose derivative
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Bishydroxylation of methyl (Z)-2,3-dideoxy-4,5:6,7-di-O-isopropylidene-β-D- arabino-oct-2-ene-4-ulo-4,8-pyranosonate 1 with osmium tetraoxide proceeded with extremed high diastereoselectivity to give only methyl 4,5:6,7-di-O-isopropylidene-β-D-arabino-L-erythro-oct-4-ulo-4,8-pyranosonate 2. Configurations of the new stereogenic centers (C-2,3) in 2 were determined by degradation of the C-5,6,7,8 fragment to the well-known methyl 2,3,4-tri-O-methyl-D-(+)-erythronate 7. Transformation of 2 into the required D-arabino-L-erythro-oct-4-ulosa 10, was achieved by a methodology that implied, protection to 8, reduction of the ester group in 8 to a hydroxymethyl group in 9, and finally deprotection to the free D-arabino-L-erythro-oct-4-ulosa 10. On the other hand, epoxidation reaction on (E)-2,3-dideoxy-4,5:6,7-di-O-isopropylidene-β-D-arabino-oct-2-ene-4-ulo-4,8 -pyranose 11 afforded only the corresponding 2,3-anhydro derivative 12 with β-D-arabino-D-threo configuration, as could be demonstrated by degradation to (S)-1,2,4-trimetoxybutane 16, which synthesis is reported herein.
- Izquierdo, Isidoro,Plaza, Maria T.,Robles, Rafael,Rodriguez, Concepcion
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p. 3593 - 3604
(2007/10/03)
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- Process for the preparation of 3,4-dihydroxybutanoic acid and salts thereof
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A process for the preparation of 3,4-dihydroxybutanoic acid (1) and salts thereof from a glucose source containing 1,4-linked glucose as a substituent is described. The process uses an alkali metal hdyroxide and hydrogen peroxide to convert the glucose source to (1). The compound (1) is useful as a chemical intermediate to naturally occurring fatty acids and is used to prepare 3,4-dihydroxybutanoic acid-gamma-lactone (2) and furanone (3), particularly stereoisomers of these compounds.
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- Enantioselective Synthesis of (S)- and (R)-6-(2,3-Dihydroxypropyl)-1,3-dioxin-4-ones: the Versatile Building Blocks of Four- and Six-carbon Backbones
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The Sharpless asymmetric epoxidation of 2,2-dimethyl-6-(3-hydroxy-1-propenyl)-1,3-dioxin-4-one using titanium tetraisopropoxide-diisopropyl tartrate followed by catalytic hydrogenation affords the title compounds as enantiomerically pure compounds, which act as versatile four- and six-carbon building blocks.
- Sakaki, Jun-ichi,Sugita, Yoshiaki,Sato, Masayuki,Kaneko, Chikara
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p. 434 - 435
(2007/10/02)
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- Absolute Stereochemistries of the Aplysiatoxins and Oscillatoxin A
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Optical and proton NMR spectral studies of the aplysiatoxins and derivatives, degradation products of the toxins and an X-ray crystallographic analysis of 19,21-dibromoaplysiatoxin show that the absolute configurations of the ten asymmetric carbons are 3S,4R,7S,9S,10S,11R,12S,15S,29R,30R.The 31-nor compound, oscillatoxin A, has the same absolute stereochemistry at C(3), C(4), C(7), C(9), C(10), C(11), C(12), C(15), and C(29).
- Moore, Richard E.,Blackman, Adrian J.,Cheuk, Chad E.,Mynderse, Jon S.,Matsumoto, Gayle K.,et al.
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p. 2484 - 2489
(2007/10/02)
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