- Hyperconjugation and the increasing bulk of OCOCX3 substituents in trans-1,4-disubstituted cyclohexanes destabilize the diequatorial conformer
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The trans diesters of 1,4-cyclohexanediol with a number of acetic acid analogues, CX3COOH, of varying steric hindrance and polarity (CX 3 = Me, Et, iso-Pr, tert-Bu, CF3, CH2Cl, CHCl2, CCl3,
- Kleinpeter, Erich,Rolla, Nadja,Koch, Andreas,Taddei, Ferdinando
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Read Online
- Complementary and selective oxidation of hydrocarbon derivatives by two cytochrome P450 enzymes of the same family
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The cytochrome P450 enzymes CYP101B1 and CYP101C1, which are from the bacterium Novosphingobium aromaticivorans DSM12444, can hydroxylate norisoprenoids with high activity and selectivity. With the goal of expanding and establishing their substrate range with a view to developing applications, the oxidation of a selection of cyclic alkanes, ketones and alcohols was investigated. Cycloalkanes were oxidised, but both enzymes displayed moderate binding affinity and low levels of productive activity. We improved the binding and activity of these substrates with CYP101B1 by making the active site more hydrophobic by switching a histidine residue to a phenylalanine (H85F). The presence of a ketone moiety in the cycloalkane skeleton significantly improved the oxidation activity with both enzymes. CYP101C1 preferably catalysed the oxidation of cycloalkanones at the C-2 position whereas CYP101B1 oxidised these substrates with higher productivity and at positions remote from the carbonyl group. This demonstrates that the binding orientation of the cyclic ketones in the active site of each enzyme must be different. Linear ketones were also oxidised by both enzymes but with lower activity and selectivity. Cyclic substrates with an ester directing group were more efficiently oxidised by CYP101B1 than CYP101C1. Both enzymes catalysed oxidation of these esters with high regioselectively on the ring system remote from the ester directing group. CYP101C1 selectively oxidised certain terpenoid ester substrates, such as α-terpinyl and citronellyl acetate more effectively than CYP101B1. Overall, we establish that the high selectivity and activity of these enzymes could provide new biocatalytic routes to important fine chemicals.
- Sarkar, Md. Raihan,Bell, Stephen G.
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p. 5983 - 5995
(2020/10/08)
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- HORMONE RECEPTOR MODULATORS FOR TREATING METABOLIC CONDITIONS AND DISORDERS
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The invention relates to activators of FXR useful in the treatment of autoimmune disorders, liver disease, intestinal disease, kidney disease, cancer, and other diseases in which FXR plays a role, having the Formula (I): (I), wherein L1, A, X1, X2, R1, R2, and R3 are described herein.
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Page/Page column 362; 363
(2018/03/25)
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- 3-PHOSPHOGLYCERATE DEHYDROGENASE INHIBITORS AND USES THEREOF
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The present invention provides compounds, compositions thereof, and methods of using the same.
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Paragraph 00916-00918
(2017/10/06)
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- Novel electrochemical deoxygenation reaction using diphenylphosphinates
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The electrochemical reduction of diphenylphosphinate esters leads smoothly and in high yields to the corresponding deoxygenated products. In comparison with the previously developed methodologies, the electrolysis could be performed at lower temperature and with a higher current density, resulting in a shorter reaction time.
- Lam, Kevin,Marko, Istvan E.
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supporting information; experimental part
p. 406 - 409
(2011/04/18)
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- P-Toluenesulfonyl chloride as a new and effective catalyst for acetylation and formylation of hydroxyl compounds under mild conditions
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The catalytic application of p-toluenesulfonyl chloride for efficient acetylation of various types of alcohols and phenols with acetic anhydride in solvent-free conditions is reported. Also structurally diverse alcohols were formylated using formic acid based on the use of catalytic amount of p-toluenesulfonyl chloride under solvent-free condition. The reactions were carried out in short reaction time and in good to excellent yields at room temperature.
- Khazaei, Ardeshir,Rostami, Amin,Mantashlo, Fatemeh
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experimental part
p. 1430 - 1434
(2011/10/08)
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- Chemoselective chemical and electrochemical deprotections of aromatic esters
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Alcohols can be easily and chemoselectively deprotected from the corresponding aromatic esters by using either SmI2/HMPA or by electrolysis In the presence of a proton source.
- Lam, Kevin,Marko, Istvan E.
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experimental part
p. 2752 - 2755
(2009/11/30)
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- Toluates: unexpectedly versatile reagents
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The mechanism of the monoelectronic reduction of aromatic esters has been investigated. The unexpected synthetic utility of the toluate moiety in the deoxygenation of alcohols and the allylation of ketones is also reported. Finally, the use of aromatic esters as robust, though easily removable, protecting groups is depicted.
- Lam, Kevin,Markó, István E.
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experimental part
p. 10930 - 10940
(2010/02/28)
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- Process for preparing monoesters
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A process for preparing monoesters comprises the step of reacting at least one diol with at least one carboxylic acid in a biphasic solvent system, the carboxylic acid being sufficiently water soluble to allow esterification to occur, and the biphasic solvent system comprising water and at least one aprotic solvent in which the resulting monoester has greater solubility than in water.
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Page/Page column 6
(2008/06/13)
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- Meerwein-Ponndorf-Verley-type reductive acetylation of carbonyl compounds to acetates by lanthanide complexes in the presence of isopropenyl acetate
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Meerwein-Ponndorf-Verley-type reductive acetylation of carbonyl compounds to acetates was successfully carried out in the presence of isopropenyl acetate under the influence of a catalytic amount of Ln(O(i)Pr)3 at room temperature. Various carbonyl compounds were converted into the corresponding acetates in fair to good yields. (C) 2000 Elsevier Science Ltd.
- Nakano, Yasushi,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 1565 - 1569
(2007/10/03)
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- Facile and highly selective monoacylation of symmetric diols adsorbed on silica gel with acetyl chloride
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Monoacetylated alcohols of symmetric 1,n-diols are synthesized quantitatively by refluxing a suspension of the diols adsorbed on silica gel with acetylchloride.
- Ogawa, Haruo,Amano, Misa,Chihara, Teiji
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p. 495 - 496
(2007/10/03)
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- Regio- and stereoselective transacylation of polyhydric alcohols using pronase in organic solvents
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Pronase a mixture of proteases from Streptomyces griseus has been found to be a good catalyst for transacylation in organic solvents.With equimolar concentrations of p-nitrophenyl acetate as acyl donor in pyridine, aliphatic diols give predominantly the monoacetates.Glucose and isomeric hexoses give the 6-O-acetates in good yield. 6-Deoxy-sugars however, yield mixtures of acetates indicating that regioselectivity among the secondary hydroxyl groups are poor.Racemic trans-1,2-cyclohexanediol affords the (1R, 2R)-monoacetate in 44percent yield with greater than 90percent enantiomer ic purity. cis-1,2-cyclohexanediol and cis-1,2-cyclohexanedimethanol also give optically active monoacetates.
- Bhattacharya, A,Ali, E
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p. 898 - 899
(2007/10/02)
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- STEREOSTRUCTURE OF RENGYOL AND ISORENGYOL, PHENYLETHANOIDS OF FORSYTHIA SUSPENSA
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Determination of the stereostructure of rengyol (1), a novel nonaromatic phenylethanoid natural product isolated from Forsythia suspensa, by synthetic means has been described.The Reformatsky reaction of 4-acetoxycyclohexanone with ethyl bromoacetate afforded two isomeric acetoxy esters (5, 6) and the one (5) which has an equatorial acetoxyl group yielded on LAH reduction a triol identified as rengyol (1).The isomer (7), obtained similarly from the other isomeric acetoxy ester (6), has also been isolated from the natural source and is named isorengyol.Further, dehydratation of the esters (5, 6) and subsequent pyrolytic deacetoxylation afforded a 1,3-cyclohaxadiene derivative (12), which on photosensitized cis-dioxygenation, followed by reduction, yielded rengyol (1) establishing its stereostructure to have 1,4-cis-cyclohexanediol system.These results supported the previous conclusion based on the 1H and 13C NMR spectral data.
- Endo, Katsuya,Seya, Kazuhiko,Hikino, Hiroshi
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p. 2681 - 2688
(2007/10/02)
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