- Efficient synthesis of α-branched purine-based acyclic nucleosides: Scopes and limitations of the method
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An efficient route to acylated acyclic nucleosides containing a branched hemiaminal ether moiety is reported via three-component alkylation of N-heterocycle (purine nucleobase) with acetal (cyclic or acyclic, variously branched) and anhydride (preferentially acetic anhydride). The procedure employs cheap and easily available acetals, acetic anhydride, and trimethylsilyl trifluoromethanesulfonate (TMSOTf). The multi-component reaction is carried out in acetonitrile at room temperature for 15 min and provides moderate to high yields (up to 88%) of diverse acyclonucleosides branched at the aliphatic side chain. The procedure exhibits a broad substrate scope of N-heterocycles and acetals, and, in the case of purine derivatives, also excellent regioselectivity, giving almost exclusively N-9 isomers.
- Dra?ínsky, Martin,Frydrych, Jan,Janeba, Zlatko,Slavětínská, Lenka Po?tová
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- PROCESS FOR THE CONVERSION OF SUGARS TO LACTIC ACID AND 2-HYDROXY-3-BUTENOIC ACID OR ESTERS THEREOF COMPRISING A METALLO-SILICATE MATERIAL AND A METAL ION
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The present invention regards metallo-silicate materials comprising a metal ion selected from one or more of the group consisting of potassium ions, sodium ions, lithium ions, rubidium ions and caesium ions. The materials are useful preparing lactic acid and 2-hydroxy-3-butenoic acid or esters thereof from a sugar.
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Paragraph 0054; 0055; 0056; 0057; 0058
(2017/03/21)
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- Les dialkoxy-2,2 ethanals, synthons difonctionnels a deux carbones : preparation par acetalisation du glyoxal et quelques applications en synthese
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Known for a long time, 2,2-dialkoxy ethanals had to be prepare by rather tedious indirect pathways since monoacetalization of glyoxal was unknown.We discovered that it is possible to acetalize only one of the glyoxal functions using a great excess of alcohol, in the presence of an active enough catalyst.With careful monitoring of the reaction, 50 to 70 percent yield of monoacetals is obtained.The monoacetal is formed much quicker than the diacetal and the maximum yield is rather quickly obtained; with further elimination of water, diacetalization proceeds at the expense of the monoacetal.Depending on azeotropic compositions and boiling points, one of the following methods is used: 1.General method: 40 percent aqueous glyoxal (1 mol), alcohol (10 mol), catalyst (0.01 to 0.1 equivalent) and solvent are refluxed with azeotropic water extraction.The monitored (GC) reaction is stopped at the most favourable moment. 2.Method without solvent, convenient for unreactive alcohols, such as i-butanol: water is evaporated from glyoxal solution (1 mol); the residue, alcohol (10 mol) and catalyst are refluxed with water azeotropic extraction. 3.Method without solvent and without water azeotropic extraction: dehydrated glyoxal (1 mol) is refluxed with alcohol (10 mol) and catalyst.This method is the most convenient for methanol and ethanol.This sample and inexpensive preparation of 2,2-dialkoxy ethanals prompted us to perform syntheses of difunctional molecules otherwise only tediously accessible, since easily obtained functionalized acetals can be hydrolysed to functionalized aldehydes which constitute interesting synthons.Hydride or catalytic reduction as well as organometallic reactions lead to alcohols, further hydrolysed into 2-hydroxy aldehydes or oxidized to give way finally to α-ketoaldehydes for which this method provides a general synthetic pathway.From the oximes, prepared by classical methods, nitriles and amines can be obtained.Starting directly from the aldahydes, amines may be prepared by hydrogenation in the presence of ammonia or amines.The reaction of 2,2-dialkoxy ethanals with amides provides hydroxy and alkoxy acetal amides.The Cannizzaro reaction was also investigated; the same reactivity is displayed by formaldehyde and glyoxal monoacetals.Other reactions, among which Wittig and Wittig-Horner, are presently being studied in our laboratory.
- Stambouli, Abdelhamid,Hamedi-Sangsari, Farid,Amouroux, Roger,Chastrette, Francine,Blanc, Alain,Mattioda, Georges
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- A ONE POT PROCESS FOR THE OBTENTION AND REACTIONS OF GLYOXAL MONOACETAL
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A THF solution of glyoxal monoacetal 1 is obtained by SWERN oxidation of 2,2-diethoxy 1-ethanol and directly submitted to diverse nucleophilic species; The expected adducts of 1 are obtained with acceptable yields.
- Bernard, Didier,Doutheau, Alain,Gore, Jacques
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p. 1807 - 1814
(2007/10/02)
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- DISSYMETRATION DE LA MOLECULE DU GLYOXAL 1-SYNTHESE ET REACTIVITE DE L'ACETOXY-1 TRIETHOXY-1,2,2 ETHANE
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Acetoxy-1 triethoxy-1,2,2 ethane, a dissymetric derivative of glyoxal, is prepared and reacted with various bases and nucleophiles, as amines, cyanotrimethylsilane, organometallic and WITTIG reagents.Various acetals are obtained, leading to α-fonctionalized aldehydes.
- Stambouli, A.,Chastrette, F.,Amouroux, R.,Chastrette, M.,Mattioda, G.,Blanc, A.
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p. 4149 - 4152
(2007/10/02)
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- SYNTHESIS AND PROPERTIES OF SOME O--GLYCOLALDEHYDES
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O-glycolaldehydes (1a-e; alkyl = Et, Pr, Pri, But, and -CH2-, respectively) have been prepared from the corresponding O-glycolaldehyde dimethyl acetals (2a-e) by acid hydrolysis.In anhydrous 1,4-dioxane in the presence of BF3*(Et2O)2, 1a-c were partially transformed into glycolaldehyde bis(dialkyl dithioacetals), 1d afforded trans-2,6-bis(tert-butylthio)-1,4-dioxane and 3,5-bis(tert-butylthio)-1,4-oxathiane, and 1e did not react.The acetals 2a-e were prepared from the appropriate glycolaldehyde dialkyl dithioacetal by O-alkylation with bromoacetaldehyde dimethyl acetal.
- Aparicio, F. J. Lopez,Benitez, F. Zorrilla,Gonzalez, F. Santoyo
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p. 287 - 296
(2007/10/02)
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