- PREPARATION OF GLUTARALDEHYDE
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Provided is a process for the preparation of glutaraldehyde. The process comprises reacting an alkoxydihydropyran with water in the presence of an acidic catalyst. The alcohol by-product distilled from the reaction mixture is subjected to a heterogeneous catalyst that is located external to the distillation column used for distilling the alcohol, thereby increasing glutaraldehyde yield and decreasing the level of alkoxydihydropyran contamination in the alcohol.
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Page/Page column 3-4
(2009/12/28)
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- Substituent effects on the SmI2/Pd(0)-promoted carbohydrate ring-contraction of 5-alkynylpyranosides
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The effect of substituents on the reactivity and stereoselectivity of the SmI2/Pd(0)-promoted ring-contraction of 5-alkynylpyranosides has been examined using substrates substituted only at selected positions. While formation of 2-ethynylcyclopentanols takes place efficiently, an internal alkyne did not afford the expected product. The presence of peripheral alkoxy substituents leads to variable stereoselectivities that depend on the number and orientation of such groups. Thus, an isolated OBn substituent at C(3) (carbohydrate numbering) exerts a significant stereochemical control while additional substitution with the same group at C(4) either enhances or drastically reduces stereoselectivity depending on its orientation (α or β, respectively).
- Aurrecoechea, José M.,Gil, Jesús H.,López, Beatriz
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p. 7111 - 7121
(2007/10/03)
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- Difunctional and Hetercyclic Prducts from the Ozonolysis of Conjugated C5-C8 Cyclodienes
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Ozonolyses of the conjugated C5-C8 cyclodienes 1a-d in methanol, followed by reduction with DMS, have been examined.Monoozonolyses gave the corresponding unsaturated dialdehydes 2e as the primary products.In subsequent reactions, the dialdehydes 2e derived from the monoozonolyses of 1a, 1b, and 1c gave in high yields the heterocyclic compounds 7, 8k, and 9k, respectively.Diozonolyses of 1a-d gave the corresponding dialdehydes 3e as the primary products.In subsequent reactions, the dialdehydes 3e derived from 1b and 1c gave the heterocyclic compounds 8l and 9l, respectively.In addition, aldehydes 2e and 3e undervent partial acetalization reactions with methanol.
- Griesbaum, Karl,Jung, In Chang,Mertens, Henri
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p. 6024 - 6027
(2007/10/02)
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- REACTION DES VINYLOGUES D'HEMIACETALS ET DE LEURS EQUIVALENTS SYNTHETIQUES SUR LES ETHERS D'ENOLS HETEROCYCLIQUES
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We describe the reaction of hemiacetal vinylogs 2 or their synthetic equivalent with cyclic enol ethers 1 yielding ketoacetals 3.Acidic treatment of these compounds leads to bicyclic heterocycles 8 or enone aldehyde 12 depending on the nature of substituents R1.
- Poirier, Jean-Marie,Dujardin, Gilles
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p. 3337 - 3340
(2007/10/02)
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- Une voie d'acces aux alcoxy-5 trimethyl-4,4,7a hexahydro-3aα,4,5,6,7,7aα (3H)-benzofurannones-2
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Starting from 2-methoxy (or ethoxy)-3,4-dihydro-2H-pyran, a series of four reactions allows to obtain a good yield of two 4-alcoxy-3,3-dimethyl-1-hydroxymethyl cyclohexenes which are converted to methylenecyclohexylacetic acids by different or sigmatropic reactions.These acids are cyclized at room temperature with concentrated sulfuric acid into bicyclic γ-lactones having a cis-junction.The stereospecificity of this reaction and the stability of the isomers obtained are discussed.
- Gosselin, Pascal,Rouessac, Francis,Zamarlik, Henri
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p. 192 - 198
(2007/10/02)
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