- THIOSEMICARBAZONES INHIBITORS OF LYSOPHOSPHATIDIC ACID ACYLTRANSFERASE AND USES THEREOF
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Lysophosphatidic acid acyltransferase-beta (LPAAT-β) catalyzes the production of phosphatidic acid (PA) from lysophosphatidic acid (LPA). The lipid cofactor PA contributes to the activation of c-Raf, BRAF, mTOR and PKC-ζ. LPAAT-β expression is a prognostic factor in gynecologic malignancies and is being investigated as a therapeutic target in a variety of tumor types. A class of thiosemicarbazones was identified as inhibitors of LPAAT-β from a screen of a library of small molecules. A focused library of thiosemicarbazones derivatives was prepared and led to the development of compounds which potently inhibit LPAAT-β and inhibit the growth of MiaPaCa2 human pancreatic cancer cells.
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Page/Page column 16
(2015/11/17)
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- Computational and Experimental Studies of Phthaloyl Peroxide-Mediated Hydroxylation of Arenes Yield a More Reactive Derivative, 4,5-Dichlorophthaloyl Peroxide
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The oxidation of arenes by the reagent phthaloyl peroxide provides a new method for the synthesis of phenols. A new, more reactive arene oxidizing reagent, 4,5-dichlorophthaloyl peroxide, computationally predicted and experimentally determined to possess enhanced reactivity, has expanded the scope of the reaction while maintaining a high level of tolerance for diverse functional groups. The reaction proceeds through a novel "reverse-rebound" mechanism with diradical intermediates. Mechanistic insight was achieved through isolation and characterization of minor byproducts, determination of linear free energy correlations, and computational analysis of substituent effects of arenes, each of which provided additional support for the reaction proceeding through the diradical pathway.
- Camelio, Andrew M.,Liang, Yong,Eliasen, Anders M.,Johnson, Trevor C.,Yuan, Changxia,Schuppe, Alex W.,Houk,Siegel, Dionicio
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p. 8084 - 8095
(2015/09/01)
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- CYCLIC PEROXIDE OXIDATION OF AROMATIC COMPOUND PRODUCTION AND USE THEREOF
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The present invention provides a method for converting an aromatic hydrocarbon to a phenol by providing an aromatic hydrocarbon comprising one or more aromatic C-H bonds and one or more activated C-H bonds in a solvent; adding a phthaloyl peroxide to the solvent; converting the phthaloyl peroxide to a di-radical; contacting the di-radical with the one or more aromatic C-H bonds; oxidizing selectively one of the one or more aromatic C-H bonds in preference to the one or more activated C-H bonds; adding a hydroxyl group to the one of the one or more aromatic C-H bonds to form one or more phenols; and purifying the one or more phenols.
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Page/Page column 10
(2014/10/15)
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- Metal-free oxidation of aromatic carbon-hydrogen bonds through a reverse-rebound mechanism
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Methods for carbon-hydrogen (C-H) bond oxidation have a fundamental role in synthetic organic chemistry, providing functionality that is required in the final target molecule or facilitating subsequent chemical transformations. Several approaches to oxidizing aliphatic C-H bonds have been described, drastically simplifying the synthesis of complex molecules. However, the selective oxidation of aromatic C-H bonds under mild conditions, especially in the context of substituted arenes with diverse functional groups, remains a challenge. The direct hydroxylation of arenes was initially achieved through the use of strong Bronsted or Lewis acids to mediate electrophilic aromatic substitution reactions with super-stoichiometric equivalents of oxidants, significantly limiting the scope of the reaction. Because the products of these reactions are more reactive than the starting materials, over-oxidation is frequently a competitive process. Transition-metal-catalysed C-H oxidation of arenes with or without directing groups has been developed, improving on the acid-mediated process; however, precious metals are required. Here we demonstrate that phthaloyl peroxide functions as a selective oxidant for the transformation of arenes to phenols under mild conditions. Although the reaction proceeds through a radical mechanism, aromatic C-H bonds are selectively oxidized in preference to activated-H bonds. Notably, a wide array of functional groups are compatible with this reaction, and this method is therefore well suited for late-stage transformations of advanced synthetic intermediates. Quantum mechanical calculations indicate that this transformation proceeds through a novel addition-abstraction mechanism, a kind of 'reverse-rebound' mechanism as distinct from the common oxygen-rebound mechanism observed for metal-oxo oxidants. These calculations also identify the origins of the experimentally observed aryl selectivity.
- Yuan, Changxia,Liang, Yong,Hernandez, Taylor,Berriochoa, Adrian,Houk, Kendall N.,Siegel, Dionicio
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p. 192 - 196
(2013/08/23)
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- A 'meta effect' in the fragmentation reactions of ionised alkyl phenols and alkyl anisoles
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The competition between benzylic cleavage (simple bond fission [SBF]) and retro-ene rearrangement (RER) from ionised ortho, meta and para RC 6H4OH and RC6H4OCH3 (R = n-C3H7, n-C4H9, n-C5H11, n-C7H15, n-C9H19, n-C 15H31) is examined. It is observed that the SBF/RER ratio is significantly influenced by the position of the substituent on the aromatic ring. As a rule, phenols and anisoles substituted by an alkyl group in meta position lead to more abundant methylene-2,4-cyclohexadiene cations (RER fragmentation) than their ortho and para homologues. This 'meta effect' is explained on the basis of energetic and kinetic of the two reaction channels. Quantum chemistry computations have been used to provide estimate of the thermochemistry associated with these two fragmentation routes. G3B3 calculation shows that a hydroxy or a methoxy group in the meta position destabilises the SBF and stabilises the RER product ions. Modelling of the SBF/RER intensities ratio has been performed assuming two single reaction rates for both fragmentation processes and computing them within the statistical RRKM formalism in the case of ortho, meta and para butyl phenols. It is clearly demonstrated that, combining thermochemistry and kinetics, the inequality (SBF/RER) metaorthopara holds for the butyl phenols series. It is expected that the 'meta effect' described in this study enables unequivocal identification of meta isomers from ortho and para isomers not only of alkyl phenols and alkyl anisoles but also in other alkyl benzene series. Copyright
- Bouchoux, Guy,Sablier, Michel,Miyakoshi, Tetsuo,Honda, Takashi
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p. 539 - 546
(2012/09/22)
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- Discovery of CS-2100, a potent, orally active and S1P3-sparing S1P1 agonist
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S1P3-sparing S1P1 agonists have attracted attention as a suppressant of autoimmunity with reduced side effects. Our synthetic efforts and extensive SAR studies led to the discovery of 10b named CS-2100 with the EC50 value of 4.0 nM for human S1P1 and over 5000-fold selectivity against S1P3. The in vivo immunosuppressive efficacy was evaluated in rats on host versus graft reaction and the ID 50 value was determined at 0.407 mg/kg. The docking studies of CS-2100 with the homology model of S1P1 and S1P3 showed that the ethyl group on the thiophene ring of CS-2100 was sterically hindered by Phe263 in S1P3, not in the case of Leu276 in S1P1. This observation gives an explanation for the excellent S1P3-sparing characteristic of CS-2100.
- Nakamura, Tsuyoshi,Asano, Masayoshi,Sekiguchi, Yukiko,Mizuno, Yumiko,Tamaki, Kazuhiko,Kimura, Takako,Nara, Futoshi,Kawase, Yumi,Shimozato, Takaichi,Doi, Hiromi,Kagari, Takashi,Tomisato, Wataru,Inoue, Ryotaku,Nagasaki, Miyuki,Yuita, Hiroshi,Oguchi-Oshima, Keiko,Kaneko, Reina,Watanabe, Nobuaki,Abe, Yasuyuki,Nishi, Takahide
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p. 1788 - 1792
(2012/04/04)
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- Stille cross-coupling reactions using vinylcyclopropylstannanes
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The Stille cross-coupling reaction between a vinylcyclopropylstannane and iodobenzene or phenol triflate provides an expedious route to 1,2-phenylvinylcyclopropanes. However, similar coupling reactions using ortho-substituted aromatic substrates also lead
- Pattenden, Gerald,Stoker, Davey A.
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experimental part
p. 1800 - 1802
(2009/12/05)
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- Dinitroalkyl aromatics polymerization retarders or inhibitors and methods for making and for using same
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A vinyl monomer inhibitor systems is disclosed which includes 2,6-dinitro-4-alkylated phenols and mixtures of 2,6-dinitro-4-alkylated phenols and 2,4-dinitro-6-alkylated phenols as well as vinyl monomer stabilized composition including an effective amount of the inhibitor systems. A method for the preparation and use is also disclosed where phenol is first alkylated under conditions that afford predominately monoalkylated phenols having a high para alkylation preference, followed by nitration of the alkylated phenols to form a dinitrated, monoalkylated product.
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- Chromium- and tungsten-triggered valence isomerism of cis-1-acyl-2-ethynylcyclopropanes via [3,3] sigmatropy of (2-acylcyclopropyl)vinylidene - Metal intermediates
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The reaction of cis vicinal acetylethynylcyclopropanes 1 with a catalytic amount of M(CO)5(THF) (M = Cr or W) in the presence of Et3N at room temperature gave ortho-substituted phenols 7 in good yields as valence isomerized products. In the absence of Et3N the reactions did not work at all. The reaction of a cyclopropane having an ester or an amide instead of an acetyl moiety with M(CO)5(THF) did not take place, whereas an ethynylvinylcyclopropane gave a mixture of 1- and 2-substituted 1,3,5-cycloheptatrienes. These valence isomerization reactions are assumed to proceed via the formation of vinylidene-metal intermediates 2 from terminal alkynyl moieties followed by [3,3]sigmatropy of 2 to give seven-membered carbene complexes 3. Copyright
- Ohe, Kouichi,Yokoi, Tomomi,Miki, Koji,Nishino, Fumiaki,Uemura, Sakae
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p. 526 - 527
(2007/10/03)
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- Metal cation-exchanged montmorillonite (Mn+-mont)-catalysed aromatic alkylation with aldehydes and ketones
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The alkylation of aromatic compounds with aldehydes and ketones in the presence of a variety of metal cation-exchanged montmorillonites (Mn+-mont; Mn+ = Zr4+, Al3+, Fe3+, Zn2+, H+, Na+) has been investigated. Al3+- and Zr4+-Monts are revealed to be effective as catalysts, while no reaction takes place with Na+-mont. Al3+-Mont-catalysed alkylation of phenol with several aldehydes produces mainly or almost solely the corresponding gem-bis(hydroxyphenyl)alkanes (bisphenols) in good yields, while that with several ketones affords selectively the corresponding alkylphenols in moderate to good yields. The alkylation always occurs at the carbonyl carbon without any skeletal rearrangement and the kind of products depends much on the steric hindrance of an electrophilic intermediary carbocation. The alkylation of anisole, veratrole and p-cresol proceeds well, while that of toluene, benzene, chlorobenzene and nitrobenzene scarcely occurs.
- Tateiwa, Jun-Ichi,Hayama, Ei,Nishimura, Takahiro,Uemura, Sakae
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p. 1923 - 1928
(2007/10/03)
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- Methods of using α-phosphonosulfonate squalene synthetase inhibitors including the treatment of atherosclerosis and hypercholesterolemia
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α-Phosphonosulfonate compounds are provided which inhibit the enzyme squalene synthetase and thereby inhibit cholesterol biosynthesis. These compounds have the formula STR1 wherein R2 is OR5 or R5a ; R3 and R5 are independently H, alkyl, arylalkyl, aryl or cycloalkyl; R5a is H, alkyl, arylalkyl or aryl; R4 is H, alkyl, aryl, arylalkyl, or cycloalkyl;, Z is H, halogen, lower alkyl or lower alkenyl; and R1 is a lipophilic group which contains at least 7 carbons and is alkyl, alkenyl, alkynyl, mixed alkenyl-alkynyl, aryl, arylalkyl, cycloalkyl, cycloalkylalkyl, heteroaryl, heteroarylalkyl, cycloheteroalkyl, cycloheteroalkylalkyl; as further defined above; including pharmaceutically acceptable salts and or prodrug esters of the phosphonic (phosphinic) and/or sulfonic acids.
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- Gas-Liquid Phase-transfer Synthesis of Phenyl Ethers and Sulphides with Carbonate as Base and Carbowax as Catalyst
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When a mixture of a phenol (or thiol) and an alkyl halide is passed, in the gaseous state, through a solid bed of potassium carbonate (or sodium hydrogencarbonate) and catalytic amounts of Carbowax 6000, contained in a glass column at 170 deg C, the corresponding ethers (or sulphides) may be collected at the outlet.The Carbowax acts in a similar manner to the crown ethers used in solid-liquid phase-transfer catalysis.The potassium carbonate-Carbowax combination allows the generation of anions up to pKa of ca. 12.The catalysis mechanism is discussed and the synthesis of several ethers and thioethers is reported, some of which are obtained only with difficulty by normal liquid-liquid phase-transfer catalysis.
- Angeletti, Enrico,Tundo, Pietro,Venturello, Paolo
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p. 1137 - 1142
(2007/10/02)
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- Thermal Rearrangement of Alkynyl Three-Membered Rings. Evidence for an Oxacycloheptatriene Intermediate
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The substituted ethynylvinyloxiranes 9a-e were obtained by condensation of vinylsulfonium ylides with acetylenic carbonyl compounds.Thermolysis of the cis isomers of 9 was investigated in both the gas phase and the liquid phase.The first procedure afforded only cyclopropanecarboxaldehydes 17a-e, the stereochemistry of which depended on the nature and position of the substituents and on the experimental conditions.In the liquid phase 9a-e rearranged to yield, besides 17a-e, dihydrooxepins 20 and 21c-e or phenol 19a, these products also being obtained from 17a-e.Moreover, thermolysis of 21c,d led to the corresponding phenols 19c,d.Compounds 19 are believed to arise from arene oxides in equilibrium with substituted oxepin intermediates.All these findings are consistent with the initial formation of an oxacycloheptatriene (22) by a Cope reaction from 9 or a retro-Claisen reaction from 17.The observed stereoselectivity of the reaction is explicable in terms of conformational preferences.
- Bourelle-Wargnier, Francoise,Vincent, Marcel,Chuche, Josselin
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p. 428 - 435
(2007/10/02)
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- Synthesis and Dediazoniation of 2-Butyl- and 2,5-Dibutylbenzenediazonium Ions
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2-Butylbenzenediazonium ion (1a) and 2,5-dibutylbenzenediazonium ion (1b) have been thermally decomposed in aqueous acid solution.In addition to the major product, the corresponding phenol, 5- and 6-membered ring products are formed (in a ratio of ca. 7:1) as well as products of elimination and substitution in the o-butyl group.The formation of the non-phenolic products is explained in terms of competing reactions of the initially formed aryl cations: cyclization by electrophilic atttack on the o-butyl group and 1,5-hydride ion transfer from the o-butyl group with concomitant elimination or reaction with the medium.Decompositions of 1a in the presence of copper(I) oxide, believed to generate aryl radicals, does not yield any measurable quantities of cyclized products, however.
- Sikkar, Rein,Martinson, Per
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p. 551 - 558
(2007/10/02)
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- Method for preparing 2,6-ditert.butylphenol
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A method for preparing 2,6-ditert.butylphenol which comprises alkylation of phenol in the presence of monotert.-butylphenol and a catalyst, viz. aluminium dissolved in phenol with gradually lowering the process temperature from 120° to 50° C and reducing the concentration of isobutylene in the mixture of isomeric butenes from 80 to 1.5 mol.%, followed by isolation of the desired product. The method according to the present invention makes it possible to achieve a high degree of conversion of isobutylene without impairing quality of the desired product. The amount of by-products formed in the process is 2-3 times as less as in the prior art methods.
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