1654-67-7Relevant academic research and scientific papers
Production process of cyclohexanecarboxylic acid
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Paragraph 0018; 0023; 0024, (2018/09/08)
The invention discloses a production process of cyclohexanecarboxylic acid and belongs to the field of chemical synthesis. Cyclohexene oxide is used herein as a starting material to react with carbondioxide, Mg powder and TMSCl (trimethylsilyl chloride); Pd/C catalytic hydrogenation is performed in the presence of an acid to obtain the cyclohexanecarboxylic acid. The production process has good safety and good operational simplicity and is suitable for industrial production.
32. Stereochemistry of the Inhibition of δ-Chymotrypsin with Optically Active Bicyclic Organophosphates: 31P-NMR Studies
Ganci, Walter,Meier, Eric J. M.,Merckling, Franco A.,Przibille, Georg,Ringeisen, Urs,Rueedi, Peter
, p. 421 - 435 (2007/10/03)
The inhibition of δ-chymotrypsin with optically active, axially and equatorially substituted trans-3-(2,4-dini-trophenoxy)-2,4-dioxa-3λ 5-phosphabicyclo[4.4.0]decan-3-ones (= hexahydro-4H-1,3,2-benzodioxaphosphorin 3-oxides) was investigated. Their inhibitory power was determined by kinetic measurements, and the stereochemical course of the reaction of stoichiometric amounts of the enzyme and inhibitor was monitored with 31P-NMR spectroscopy at pH 7.8. The irreversible inhibitors show significant enantioselectivity (the (Sp)-enantiomer reacting faster) and yield diastereoisomeric, covalently phosphorylated derivatives of δ-chymotrypsin. 31P-NMR Spectroscopic studies of the inhibition by the axially substituted inhibitor revealed for the racemic (±)-2a first a resonance at -4.4 ppm and later, while inhibition proceeded, a second one at -4.5 ppm. The reaction with optically active (+)-2a showed only one signal at -4.4 ppm and its enantiomer (-)-2a only one signal at -4.5 ppm. Using the equatorially substituted racemic epimer (±)-2b, we observed the main resonance at -5.3 ppm and two minor ones at -4.4 and -4.5 ppm. The optically active compound (+)-2b showed two peaks at -4.5 and -5.3 ppm, whereas its antipode (-)-2b revealed two signals at -4.4 and -5.3 ppm. Comparing the 31P chemical shifts of the corresponding covalent phosphoserine derivatives 4a ( -5.7 ppm, axial) and 4b (-4.5ppm, equatorial) shows the inhibition with the axial compounds 2a to proceed via neat inversion of the configuration at the P-atom. whereas the equatorial epimers 2b with a higher conformational flexibility seem to follow a different stereochemical pathway which results in both inversion and retention.
Microbial hydroxylation of 2-cycloalkylbenzoxazoles. Part II. Determination of product structures and enhancement of enantiomeric excess
De Raadt,Griengl,Petsch,Plachota,Schoo,Weber,Braunegg,Kopper,Kreiner,Zeiser
, p. 473 - 490 (2007/10/03)
The determinations of product structures obtained in the microbial hydroxylations of various 2-cycloalkyl-1,3-benzoxazoles using Cunninghamella blakesleeana DSM 1906 and Bacillus megaterium DSM 32 are described. The initially low e.e of 3-(benz-1,3-oxazol
Chemoselective Enzymatic Hydrolysis of Aliphatic and Alicyclic Nitriles
Raadt, Anna de,Klempier, Norbert,Faber, Kurt,Griengl, Herfried
, p. 137 - 140 (2007/10/02)
Mild and selective hydrolysis of aliphatic and alicycic nitriles leading to carboxylic acids and amides was achieved under neutral conditions by an immobilized enzyme preparation from Rhodococcus sp.This method is particularly useful for the transformation of compounds containing other acid- or basesensitive groups.
Selective transformation of nitriles into amides and carboxylic acids by an immobilized nitrilase
Klempier,De Raadt,Faber,Grieng
, p. 341 - 344 (2007/10/02)
Using an immobilized nitrilase from Rhodococcus sp. mild and selective hydrolysis of nitriles can be achieved even in the presence of acid or base sensitive groups under neutral conditions. This method is applicable to a broad range of substrates as exemplified by aliphatic, alicyclic, heterocyclic and carbohydrate type nitriles.
Reduction of Substituted Δ2-Isoxazolines. Synthesis of β-Hydroxy Acid Derivatives
Curran, Dennis P.,Scanga, Susan A.,Fenk, Christopher J.
, p. 3474 - 3478 (2007/10/02)
Three separate methods are reported for the formation of β-hydroxy acid derivatives from readily available substituted Δ2-isoxazolines.Cycloaddition of 2,2-dimethylpropanenitrile oxide with a variety of olefins followed by reductive cleavage produces α '-tert-butyl β-hydroxy ketones.These are cleaved to β-hydroxy tert-butyl esters by Baeyer-Villiger oxidation with peroxytrifluoroacetic acid.In the second approach, α ',β-dihydroxy ketones are generated via cycloaddition of olefins with the nitrile oxide generated from 2--2-methyl-1-nitropropane followed by reductive ring opening.Standard periodic acid cleavage gives β-hydroxy acids.Finally, 3-methoxy-substituted Δ2-isoxazolines, readily available via benzenesulfonylcarbonitrile oxide-olefin cycloaddition and methoxide displacement, are directly reduced to β-hydroxy esters.
144. Ueber die Stereoselektivitaet der α-Alkylierung von (1R,2S)(+)-cis-2-Hydroxy-cyclohexancarbonsaeureaethylester
Frater, Gyoergy
, p. 1383 - 1390 (2007/10/02)
In continuation of our work on the stereoselectivity of the α-alkylation of β-hydroxyesters , we studied this reaction with the title compound (+)-2.The latter was prepared through reduction of 1 with baker's yeast.Alkylation of the dianion of (+)-
