- An improved synthesis of phosphonomethyl analogues of glyceraldehyde-3-phosphate and dihydroxy-acetone phosphate
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Compounds 1 and 2, phosphonate analogues of dihydroxy-acetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP) respectively, are easily and quantitatively obtained from diethyl-4,4-diethoxy-3-hydroxybutyl-1-phosphonate 3. Depending upon the acidic conditions utilised for the deprotection of the phosphonate and carbonyl groups, the aldol/ketol rearrangement allows the synthesis of either compound.
- Page,Blonski,Perie
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- Chemoenzymatic synthesis of 5-thio-D-xylopyranose
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5-thio-D-xylopyranose, a synthon used for the preparation of drugs with antithrombotic activity, was synthesised by an enzymatic isomerisation from the corresponding ketose, 5-thio-D-xylulofuranose, with glucose isomerase. This compound was obtained by two different chemoenzymatic routes, the key step being the stereospecific formation of a C-C bond, catalysed by transketolase or fructose-1,6-bisphosphate aldolase. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Charmantray, Franck,Dellis, Philippe,Helaine, Virgil,Samreth, Soth,Hecquet, Laurence
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- Fructose-6-phosphate aldolases as versatile biocatalysts for nitrocyclitol syntheses
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Efficient and stereoselective polyhydroxylated nitrocyclitol syntheses were performed via biocatalysed aldol reactions. The key step was based on a one-pot/one-enzyme cascade reaction process where two reactions occur: aldolase-catalysed aldolisation and spontaneous intramolecular nitroaldolisation. The synthetic methodology was investigated using fructose-6-phosphate aldolase A129S for the synthesis of known nitrocyclitols. Improvements were obtained which involved less steps and increased yields. Several new nitrocyclitols were also prepared using hydroxyacetone (HA) as the donor and FSA wt. From nitrocyclitol stereochemical analyses, the intramolecular nitro-Henry reaction stereoselectivity was dependent on the donor substrate used, HA or dihydroxyacetone (DHA). Whereas DHA provided two stereoisomers, four were obtained using HA.
- Camps Bres, Flora,Guerard-Helaine, Christine,Fernandes, Carlos,Castillo, Jose A.,Lemaire, Marielle
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p. 1175 - 1181
(2013/10/08)
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- Synthesis of phosphono analogues of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate
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The present paper describes the synthetic routes of six phosphono analogues of dihydroxyacetone phosphate and five phosphono analogues of glyceraldehyde 3-phosphate through α-, β- and γ-hydroxyphosphonate esters precursors containing a protected carbonyl
- Page, Patrick,Blonski, Casimir,Perie, Jacques
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p. 1403 - 1412
(2007/10/03)
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- Stereoselectivity of Baker's yeast reduction of 2-propanones: influence of substituents.
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The stereoselectivity of Baker's yeast reduction of prochiral alpha-oxygenated 2-propanones has been studied by varying the substrate structure. The 1-hydroxy-3-methoxy-3-propanone 1a was reduced to the corresponding alcohol (R)-2a with 88% enantiomeric excess. Replacing the hydroxy group in 1a with phenoxy or benzyloxy (1b and 1c) gave the alcohols (S)-2b and (S)-2c with 53 and 32% ee, respectively. Reduction of the methyl ketone 1d gave the alcohol (S)-2d with 91% ee. Attempts to improve the enantioselectivity of the reduction of 1c by lowering the substrate concentration or addition of selective reductase inhibitors had only small effect on the enantioselectivity.
- Waagen,Partali,Hollingsaeter,Huang,Anthonsen
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p. 506 - 510
(2007/10/02)
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- Chemical model for a mechanism of inactivation of monoamine oxidase by heterocyclic compounds. Electronic effects on acetal hydrolysis
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Monoamine oxidase (MAO) was shown previously to undergo time-dependent inhibition by S-(aminomethyl)-3-(4-methoxyphenyl)-2-oxazolidinone (3, X = N, Y = O, R = Me, R' = H), cis- and trans-5-(aminomethyl)-3-(4-methoxyphenyl)dihydrofuran-2(3H)-one(5, R = Me), and 4-(aminomethyl)-l-(4-methoxyphenyl)-2-pyrrolidinone(6, R = Me). Two approaches are taken in this article to test the hypothesis that the cause for this inhibition is electron-withdrawing stabilization of an enzyme adduct by the heterocycles. First, the rates of reactivation of the inhibited enzyme were measured, and they correlated qualitatively with the strengths of the electron-withdrawing abilities of the heterocycles. The second approach was a chemical model study for the proposed enzyme adduct stabilities. The corresponding acetals were synthesized, and the rates of acid hydrolysis of these acetals were used as a model for the decomposition of the enzyme adducts; the rates of hydrolysis should be a qualitative measure of the stabilities of the enzyme adducts. An inverse relationship was observed between the strength of the electron-withdrawing effect of the heterocycle and the rate of acetal hydrolysis. These results support the hypothesis that inhibition of MAO by heterocyclic compounds results from electronic stabilization of the enzyme adducts produced. This realization should prove to be very beneficial to the design of new classes of MAO inhibitors. Furthermore, it cautions synthetic chemists as to the problems associated with acetal deprotection of aldehydes when electron-withdrawing groups are even three bonds away from the acetal carbon.
- Silverman, Richard B.,Ding, Charles Z.
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p. 4571 - 4576
(2007/10/02)
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- Synthesis of Simple Oxetanes Carrying Reactive 2-Substituents
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Ring-expansion of substituted epoxides using dimethyloxosulphonium methylide provides a convenient route to oxetanes carrying reactive 2-substituents that are capable of further modification.
- Fitton, Alan O.,Hill, John,Jane, David E.,Millar, Ross
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p. 1140 - 1142
(2007/10/02)
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- A Chemoenzymatic Synthesis of Leukotriene B4
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A total synthesis of leukotriene B4 (1) is accomplished by the assembly of the key chirons 2 and 3, which are prepared via enzymatic methods.
- Han, Chao-Qi,DiTullio, Dennis,Wang, Yi-Fong,Sih, Charles J.
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p. 1253 - 1258
(2007/10/02)
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