cas 1835-04-7, 1-(3,4-DIMETHOXY-PHENYL)-PROPAN-1-ONE

Articles about 1835-04-7Total 39 be found

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Adams et al.
p. 528,532
(1941)
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Friedel-Crafts propionylation of veratrole to 3,4-dimethoxypropiophenone over superacidic UDCaT-5 catalyst
3,4-Dimethoxypropiophenone (3,4-DMPP) is of considerable commercial importance due to its use in fine chemical and drug industries. 3,4-DMPP is traditionally produced by the Friedel-Crafts propionylation of veratrole using homogeneous catalysts which are
Yadav, Ganapati D.,More, Santosh R.
p. 123 - 130
(2012)
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Cleavage of CC and Co bonds in β-O-4 linkage of lignin model compound by cyclopentadienone group 8 and 9 metal complexes
Degradation of 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphe-noxy)propane-1,3-diol (1), a model compound for lignin β-O-4 linkage was examined with iron, ruthenium, rhodium and iridium complexes bearing cyclopentadienone ligand. Cyclopentadienone iron complex gave only a small amount of degraded product with reduced molecular weight. Cyclopentadienone ruthenium complex, so called Shvo's catalyst, afforded 3,4-dimethoxybenzaldehyde (a3) in 14.3% yield after CαCβ bond cleavage. On the other hand, cyclopentadienone group-9 metal complexes catalyzed CβO bond cleavage to afford guaiacol (b1) as a main product in up to 74.9% yield.
Kishino, Masamichi,Kusumoto, Shuhei,Nozaki, Kyoko
supporting information
p. 477 - 480
(2020/05/19)

Cobalt-Catalyzed Migrational Isomerization of Styrenes
An efficient cobalt-catalyzed migrational isomerization of styrenes was developed using the thiazoline iminopyridine (TIP) ligand. This reaction is operationally simple and atom-economical using readily available starting materials to access trisubstituted alkenes. Even when using a 0.1 mol % catalyst loading, the reaction could be conducted in neat and completed in 1 h with excellent conversion and high E stereoselectivity.
Zhao, Jiajin,Cheng, Biao,Chen, Chenhui,Lu, Zhan
supporting information
p. 837 - 841
(2020/01/31)

Preparation method and application of apocynin and derivatives of apocynin
The invention belongs to the technical field of chemical biology, and particularly relates to a preparation method of apocynin and derivatives of the apocynin and an application of the apocynin and the derivatives of the apocynin in skin care products. The apocynin and the derivatives of the apocynin provided by the invention can promote collagen synthesis, help skin damage repair, and can be usedin the skin care products.
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Paragraph 0067-0070

(2020/01/12)

Rhodium-terpyridine catalyzed redox-neutral depolymerization of lignin in water
Simple rhodium terpyridine complexes were found to be suitable catalysts for the redox neutral cleavage of lignin in water. Apart from cleaving lignin model compounds into ketones and phenols, the catalytic system could also be applied to depolymerize dioxasolv lignin and lignocellulose, affording aromatic ketones as the major monomer products. The (hemi)cellulose components in the lignocellulose sample remain almost intact during lignin depolymerization, providing an example of a "lignin-first" process under mild conditions. Mechanistic studies suggest that the reaction proceeds via a rhodium catalyzed hydrogen autotransfer process.
Liu, Yuxuan,Li, Changzhi,Miao, Wang,Tang, Weijun,Xue, Dong,Xiao, Jianliang,Zhang, Tao,Wang, Chao
supporting information
p. 33 - 38
(2020/01/13)

Mild Redox-Neutral Depolymerization of Lignin with a Binuclear Rh Complex in Water
A mild redox-neutral lignin depolymerization system featuring a water-soluble binuclear Rh complex has been developed. The catalytic system could be successfully applied to the depolymerization of a lignin-like polymer, alkaline lignin, as well as raw lignocellulose samples to produce aromatic ketones, providing a homogeneous catalytic system for "lignin-first" biorefinery in water. Mechanistic studies on the model substrate suggest that the reaction proceeds via a metal-catalyzed dehydrogenation step to afford a carbonyl intermediate, followed by C-O bond cleavage to afford ketone and phenol products. Deuterium labeling study shows that the hydrogen used for cleavage of the C-O bond originates from the alcohol moiety in the substrate.
Liu, Yuxuan,Li, Changzhi,Miao, Wang,Tang, Weijun,Xue, Dong,Li, Chaoqun,Zhang, Bo,Xiao, Jianliang,Wang, Aiqin,Zhang, Tao,Wang, Chao
p. 4441 - 4447
(2019/05/14)

METHOD FOR THE DEACYLATION AND/OR DEALKYLATION OF COMPOUNDS
The present invention in general relates to a method for the deacylation and/or dealkylation (both O-dealkylation as well as C-dealkylation) of compounds, more specifically of aromatic compounds. The method is characterized by contacting the compound with an acid-containing aqueous reaction mixture using high temperature and high pressure conditions. The invention also provides a method for preparing a compound suitable for further deacylation using the method of the invention.
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Page/Page column 24; 34; 40

(2019/02/15)

A convenient synthetic approach to dioncoquinone B and related compounds
A total synthesis of dioncoquinone B and related compounds, including ancistroquinones B, C and malvon A, is presented. The strategy is based on available reagents and can be used as a preparative synthesis of a number of natural and synthetic biologically active (3-alkyl)-2,7,8-di(tri)methoxy(hydroxy)-1,4-naphthoquinones.
Khmelevskaya, Ekaterina A.,Pelageev, Dmitry N.
supporting information
p. 1022 - 1024
(2019/03/13)

Visible-Light-Driven Self-Hydrogen Transfer Hydrogenolysis of Lignin Models and Extracts into Phenolic Products
Obtaining high selectivity of aromatic monomers from renewable lignin has been extensively pursued but is still unsuccessful, hampered by the need to efficiently cleave C-O/C-C bonds and inhibit lignin proliferation reactions. Herein, we report a transfer hydrogenolysis protocol using a heterogeneous ZnIn2S4 catalyst driven by visible light. In this process, alcoholic groups (CαH-OH) of lignin act as hydrogen donors. Proliferation of phenolic products to dark substances is suppressed under visible light illumination at low temperature (below 50 °C); formation of a light and transparent reaction solution allows visible light to be absorbed by the catalyst. With this strategy, 71-91% yields of phenols in the conversion of lignin β-O-4 models and a 10% yield of p-hydroxyl acetophenone derivatives from organosolv lignin are achieved. Mechanistic studies reveal that CαH-OH groups of lignin β-O-4 linkage are initially dehydrogenated on ZnIn2S4 to form a "hydrogen pool", and the adjacent Cβ-O bond is subsequently hydrogenolytically cleaved to two monomers by the "hydrogen pool". Thus, the dehydrogenation and hydrogenolysis reaction are integrated in one-pot with lignin itself as a hydrogen donor. This study shows a promising way of supplying phenolic compounds by taking advantages of both renewable biomass feedstocks and photoenergy.
Luo, Nengchao,Wang, Min,Li, Hongji,Zhang, Jian,Hou, Tingting,Chen, Haijun,Zhang, Xiaochen,Lu, Jianmin,Wang, Feng
p. 4571 - 4580
(2017/07/24)

Method for degrading lignin
The invention discloses a method for degrading lignin. Water is used as a solvent. The method includes carrying out reaction on the lignin under the effects of double-rhodium catalysts or terpyridine rhodium trichloride catalysts and alkali under the protection of inert gas at the temperatures of 100-120 DEG C for 10-16 hours to degrade the lignin. Compared with existing methods, the method has the advantages that extra hydrogen sources can be omitted, the water is used as the solvent, reaction conditions are mild, the method is easy to implement, high in reaction yield and low in industrial production cost and is green and environmentally friendly, and environmental pollution can be abated.
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Paragraph 0048; 0049; 0050

(2017/10/28)

Promoting Lignin Depolymerization and Restraining the Condensation via an Oxidation-Hydrogenation Strategy
For lignin valorization, simultaneously achieving the efficient cleavage of ether bonds and restraining the condensation of the formed fragments represents a challenge thus far. Herein, we report a two-step oxidation-hydrogenation strategy to achieve this goal. In the oxidation step, the O2/NaNO2/DDQ/NHPI system selectively oxidizes CαH-OH to Cα=O within the β-O-4 structure. In the subsequent hydrogenation step, the α-O-4 and the preoxidized β-O-4 structures are further hydrogenated over a NiMo sulfide catalyst, leading to the cleavage of Cβ-OPh and Cα-OPh bonds. Besides the transformation of lignin model compounds, the yield of phenolic monomers from birch wood is up to 32% by using this two-step strategy. The preoxidation of CαH-OH to Cα=O not only weakens the Cβ-OPh ether bond but also avoids the condensation reactions caused by the presence of Cα+ from dehydroxylation of CαH-OH. Furthermore, the NiMo sulfide prefers to catalyze the hydrogenative cleavage of the Cβ-OPh bond connecting with a Cα=O rather than catalyze the hydrogenation of Cα=O back to the original CαH-OH, which further ensures and utilizes the advantages of preoxidation.
Zhang, Chaofeng,Li, Hongji,Lu, Jianmin,Zhang, Xiaochen,Macarthur, Katherine E.,Heggen, Marc,Wang, Feng
p. 3419 - 3429
(2017/06/09)

KOtBu-Mediated Domino Isomerization and Functionalization of Aromatic Allylic Alcohols
Transition-metal- as well as ligand-free base-mediated domino isomerization and alkylation of allylic alcohols is presented. This protocol features the conversion of simple allylic alcohols into the corresponding ketones through isomerization in the presence of a simple base. Significantly, these in situ generated ketones subsequently undergo alkylation with styrenes as electrophiles, in a domino one-pot fashion, as an atom- and step-economical chemical process.
Suchand, Basuli,Satyanarayana, Gedu
supporting information
p. 3886 - 3895
(2017/07/22)

An efficient and green method for regio- and chemo-selective Friedel-Crafts acylations using a deep eutectic solvent ([CholineCl][ZnCl2]3)
[CholineCl][ZnCl2]3, a deep eutectic solvent between choline chloride and ZnCl2, has been used as a dual function catalyst and green solvent for the Friedel-Crafts acylation of aromatic compounds instead of using the moisture-sensitive Lewis acids and volatile organic solvents. The reactions are performed with high yields under microwave irradiation with short reaction times for the synthesis of ketones. Interestingly, indole derivatives are regioselectively acylated in the 3-position under mild conditions with high yields without NH protection. Three new ketone products are synthesized. [CholineCl][ZnCl2]3 is easily synthesized from choline chloride and zinc chloride at a low cost, with easy purification and environmentally benign compounds. [CholineCl][ZnCl2]3 can be reused up to five times without loss of catalytic activity, making it ideal in industrial processes.
Tran, Phuong Hoang,Nguyen, Hai Truong,Hansen, Poul Erik,Le, Thach Ngoc
p. 37031 - 37038
(2016/05/24)

Substituent effects at the benzyl position and aromatic ring of silane-coupling agents containing 2-nitrobenzyl esters on photosensitivity and hydrophobic surface of a self-assembled monolayer (SAM)
Silane-coupling agents with 2-nitrobenzyl esters containing alkyl substituents at the benzyl position and alkoxy and/or fluoroalkoxy groups of the aromatic ring were synthesized to prepare a self-assembled monolayer (SAM) on quartz glass, silicon wafer and thermally oxidized silicon wafer. The resulting photosensitive SAMs before and after photoirradiation were characterized by contact angle measurement, UV spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray reflectivity (XRR). Photosensitivity of the SAM was influenced by substituents at the benzyl position and aromatic ring as well as the irradiation conditions in air or solution and substrates employed. Silane-coupling agents with bulky substituent at the benzyl position and double fluoroalkoxy chains are preferable in terms of the photosensitivity and hydrophobic surface.
Konishi, Tsubasa,Hashimoto, Teppei,Sato, Naoya,Nakajima, Kazuki,Yamaguchi, Kazuo
p. 125 - 134
(2016/01/27)

Ruthenium-Catalyzed C-C bond cleavage in lignin model substrates
Ruthenium-triphos complexes exhibited unprecedented catalytic activity and selectivity in the redox-neutral C-C bond cleavage of the β-O-4 lignin linkage of 1,3-dilignol model compounds. A mechanistic pathway involving a dehydrogenation-initiated retro-aldol reaction for the C-C bond cleavage was proposed in line with experimental data and DFT calculations.
Vom Stein, Thorsten,Den Hartog, Tim,Buendia, Julien,Stoychev, Spas,Mottweiler, Jakob,Bolm, Carsten,Klankermayer, Jürgen,Leitner, Walter
supporting information
p. 5859 - 5863
(2015/05/13)

Hydrogenolysis of a γ-Acetylated Lignin Model Compound with a Ruthenium-Xantphos Catalyst
Catalytic hydrogenolysis of a γ-acetylated dimer lignin model compound is effected using a Ru-xantphos catalyst. Mechanistic investigations show mono-aryl degradation products are generated from the β-O-4 substrate as well as a terminal alkene ketone dimer (bis-aryl) that further dimerizes to a tetra-aryl product. Preliminary results using an acetylated kraft lignin as a substrate are also discussed. Graphical Abstract: [Figure not available: see fulltext.]
Wu, Adam,Lauzon, Jean Michel,James, Brian R.
p. 511 - 518
(2015/08/04)

Selective aerobic benzylic alcohol oxidation of lignin model compounds: Route to aryl ketones
A mild and chemoselective oxidation of the α-alcohol in β-O-4'-ethanoaryl and β-O-4'-glycerolaryl ethers has been developed. The benzylic alcohols were selectively dehydrogenated to the corresponding ketones in 60-93-% yield. A one-pot selective route to aryl ethyl ketones was performed. The catalytic system comprises recyclable heterogeneous palladium, mild reaction conditions, green solvents, and oxygen in air as oxidant. Catalytic amounts of a coordinating polyol were found pivotal for an efficient aerobic oxidation. The ligninator: A mild and chemoselective oxidation of the α-alcohol in β-O-4' lignin model compounds is developed. The benzylic alcohols are selectively dehydrogenated to the corresponding ketones in 60-93-% yield. A one-pot selective route to aryl ethyl ketones is performed. The catalytic system comprises recyclable heterogeneous palladium, mild reaction conditions, green solvents, and oxygen in air as oxidant.
Dawange, Monali,Galkin, Maxim V.,Samec, Joseph S. M.
p. 401 - 404
(2015/03/04)

SUBSTITUTED 6, 7-DIALKOXY-3-ISOQUINOLINE DERIVATIVES AS INHIBITORS OF PHOSPHODIESTERASE 10 (PDE 10A)
The invention relates to compounds of the formula or a pharmaceutically acceptable salt thereof, wherein R′, R1 through R7 and Ar are as defined herein. These compounds are useful as inhibitors of phosphodiesterase 10 (PDE10A) which are useful in treating central nervous system diseases such as psychosis and also in treating, for example, obesity, type II diabetes, metabolic syndrome, glucose intolerance, pain and ophthalmic diseases.
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Paragraph 0377

(2015/06/17)

Formic-acid-induced depolymerization of oxidized lignin to aromatics
Lignin is a heterogeneous aromatic biopolymer that accounts for nearly 30% of the organic carbon on Earth and is one of the few renewable sources of aromatic chemicals. As the most recalcitrant of the three components of lignocellulosic biomass (cellulose, hemicellulose and lignin), lignin has been treated as a waste product in the pulp and paper industry, where it is burned to supply energy and recover pulping chemicals in the operation of paper mills. Extraction of higher value from lignin is increasingly recognized as being crucial to the economic viability of integrated biorefineries. Depolymerization is an important starting point for many lignin valorization strategies, because it could generate valuable aromatic chemicals and/or provide a source of low-molecular-mass feedstocks suitable for downstream processing. Commercial precedents show that certain types of lignin (lignosulphonates) may be converted into vanillin and other marketable products, but new technologies are needed to enhance the lignin value chain. The complex, irregular structure of lignin complicates chemical conversion efforts, and known depolymerization methods typically afford ill-defined products in low yields (that is, less than 10-20wt%). Here we describe a method for the depolymerization of oxidized lignin under mild conditions in aqueous formic acid that results in more than 60wt% yield of low-molecular-mass aromatics. We present the discovery of this facile C-O cleavage method, its application to aspen lignin depolymerization, and mechanistic insights into the reaction. The broader implications of these results for lignin conversion and biomass refining are also considered.
Rahimi, Alireza,Ulbrich, Arne,Coon, Joshua J.,Stahl, Shannon S.
p. 249 - 252
(2015/03/30)

A versatile synthesis of O-desmethylangolensin analogues from methoxy-substituted benzoic acids
The synthesis of O-desmethylangolensin (O-DMA) analogues from methoxy-substituted benzoic acids was described. Treatment of methoxy-substituted benzoic acids with 2 equiv of ethyllithium afforded methoxypropiophenones, which were subsequently transformed to ethyl 2-(methoxyphenyl)propionates via 1,2-rearrangement of the methoxyphenyl group using Pb(OAc)4/HClO4 in triethyl orthoformate. After hydrolysis with KOH, the 2-(methoxyphenyl)propionic acids were reacted with di- 2-pyridyl carbonate to afford 2-pyridyl 2-(methoxyphenyl)propionates, which were acylated with methoxy-substituted phenylmagnesium bromides to give methoxy-α-methyldesoxybenzoins. The methoxy groups of these compounds were selectively or fully demethylated using boron tribromide to give diverse O-DMA analogues in high yields.
Hong, Hyo Jeong,Lee, Jae In
p. 569 - 574
(2015/02/05)

Selective route to 2-propenyl aryls directly from wood by a tandem organosolv and palladium-catalysed transfer hydrogenolysis
A tandem organosolv pulping and Pd-catalysed transfer hydrogenolysis depolymerisation and deoxygenation has been developed. The tandem process generated 2-methoxy-4-(prop-1-enyl)phenol in 23 % yield (92 % theoretical monomer yield) starting from pine wood and 2,6-dimethoxy-4-(prop-1-enyl)phenol in 49 % yield (92 % theoretical monomer yield) starting from birch wood. Only endogenous hydrogen from wood was consumed, and the reaction was performed using green solvents.
Galkin, Maxim V.,Samec, Joseph S.M.
p. 2154 - 2158
(2014/11/08)

DMF as carbon source: Rh-catalyzed α-methylation of ketones
An unprecedented Rh-catalyzed direct methylation of ketones with N,N-dimethylformamide (DMF) is disclosed. The reaction shows a broad substrate scope, tolerating both aryl and alkyl ketones with various substituents. Mechanistic studies suggest that DMF delivers a methylene fragment followed by a hydride in the methylation process.
Li, Yang,Xue, Dong,Lu, Wei,Wang, Chao,Liu, Zhao-Tie,Xiao, Jianliang
supporting information
p. 66 - 69
(2014/01/23)

SUBSTITUTED 6,7-DIALKOXY-3-ISOQUINOLINE DERIVATIVES AS INHIBITORS OF PHOSPHODIESTERASE 10 (PDE10A)
The invention relates to compounds of formula (I) or a pharmaceutically acceptable salt thereof, wherein R', R1 through R7 and Ar are as defined herein. These compounds are useful as inhibitors of phosphodiesterase 10 (PDE10A) which are useful in treating central nervous system diseases such as psychosis and also in treating, for example, obesity, type II diabetes, metabolic syndrome, glucose intolerance, pain and ophthalmic diseases.
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Page/Page column 62; 63; 65

(2014/05/24)

Synthesis of nordihydroguaiaretic acid derivatives and their bioactivities on S. pombe and K562 cell lines
Nordihydroguaiaretic acid (NDGA) and its synthetic analogues are potentially useful in treating diseases related to cancers, diabetes, viral and bacterial infections, and inflammation. In this paper, we report the optimal synthetic methods and the bioactivity study of terameprocol 2, NDGA derivative 3, and its cyclized analogue 4. The IC50 of these three compounds 2, 3 and 4 on the growth metabolism of Schizosacchromyces pombe and K562 cell lines were determined by microcalorimetry. The preliminary results showed that the compounds 2, 3 and 4 possessed good inhibition activities on S. pombe and K562 cell lines, and exhibited bidirectional biological effect and Hormesis effect. In particular, terameprocol 2 was found to possess the most potent inhibitory effect on K562 cell lines.
Li, Xu,Jiang, Jian-Hong,Chen, Qingqi,Xiao, Sheng-Xiong,Li, Chuan-Hua,Gu, Hui-Wen,Zhang, Hui,Hu, Ji-Lin,Yao, Fei-Hong,Li, Qiang-Guo
p. 605 - 613
(2013/06/05)

Acylation of aromatic ethers using different carboxylic acid anhydrides as acylating agents in the presence of nontoxic, noncorrosive resin amberlyst 15 as a solid acid catalyst
Friedel-Crafts acylation of aromatic ethers, anisole, 2-methoxynaphthalene, and dimethoxybenzenes with different acid anhydrides is carried out in the presence of an inexpensive and nonhazardous solid acid, Amberlyst 15. The catalyst is reusable, thus making the process environmentally friendly.
Pande, Manoj A.,Samant, Shriniwas D.
experimental part
p. 754 - 761
(2011/04/12)

SCALABLE SYNTHETIC PROCESS FOR MAKING TERAMEPROCOL
A manufacturing process for making terameprocol (1) which includes the following reaction scheme, wherein a first general reaction is the formation of a furan intermediate (39) and a second general reaction is the ring-reduction and ring-opening of the furan intermediate (39) to form the terameprocol (1)
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Page/Page column 28-29

(2010/04/03)

Methods of using diaminopyrimidine P2X3 and P2X2/3 receptor modulators for treatment of respiratory and gastrointestinal diseases
Methods for treating respiratory and gastrointestinal diseases mediated by a P2X3 and/or a P2X2/3 receptor antagonist, the methods comprising administering to a subject in need thereof an effective amount of a compound of formula (I): or a pharmaceutically acceptable salt thereof, wherein D, X, Y, R1, R2, R3, R4, R5, R6, R7 and R8 are as defined herein.
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Page/Page column 86

(2010/11/26)

Simple route to 3-(2-indolyl)-1-propanones via a furan recyclization reaction
A simple route to 1-R-3-(2-indolyl)-1-propanones has been elaborated based on recyclization of 2-(2-aminobenzyl)furan derivatives. Being a modification of the Reissert indole synthesis, our approach employs the furan ring as a source of carbonyl function. This approach is general and allows varying of substituents in aromatic ring as well as in 3-position of indole nucleus.
Butin, Alexander V.,Smirnov, Sergey K.,Stroganova, Tatyana A.,Bender, Wolfgang,Krapivin, Gennady D.
p. 474 - 491
(2007/10/03)

Microwave- and ultrasound-assisted semisynthesis of natural methoxylated propiophenones from isomeric mixture of phenylpropenes in minutes
A rapid and practical semisynthesis of natural methoxylated propiophenones (3a-3f) is realized by reacting stereo- and regio-isomeric mixture of phenylpropenes (1a-1f) with a catalytic amount of palladium chloride - sodium formate in formic acid, methanol, and water (2:1:2) into single product phenylpropanes (2a-2f) followed by its oxidation with 2,3-dichloro-5,6- dicyanobenzoquinone (DDQ) in wet dioxane, containing a few drops of formic acid. Conventional, ultrasound, and microwave heating were compared through these studies.
Joshi, Bhupendra P.,Sharma, Anuj,Sinha, Arun K.
p. 1826 - 1832
(2007/10/03)

DFRC Method for Lignin Analysis. 1. New Method for β-Aryl Ether Cleavage: Lignin Model Studies
A new method for selective and efficient cleavage of arylglycerol-β-aryl (β-O-4) ether linkages in lignins is described and applied to several lignin β-ether models. The term "DFRC" was coined for derivatization followed by reductive cleavage. Derivatization, accompanied by cell wall solubilization, is accomplished with acetyl bromide (AcBr); reductive cleavage of resulting β-bromo ethers utilizes zinc in acetic acid. Degradation monomers, 4-acetoxycinnamyl acetates, from β-ether cleavage by the DFRC method were identified by NMR, GC-MS, and comparison of GC retention times with authentic compounds. Under the conditions used in this study, the β-ether linkage of all models was cleaved in very high (>92%) yield. The DFRC method produces simpler mixtures of monomers with higher yields than alternative hydrolytic methods. Because of its relative simplicity, mild conditions, and exceptional selectivity, this method should become a powerful analytical method for lignin characterization.
Lu, Fachuang,Ralph, John
p. 4655 - 4660
(2007/10/03)

Mechanism of isomerization of 4-propyl-o-quinone to its tautomeric p- quinone methide
In previous work, we showed that o-quinones (3,5-cyclohexadiene-1,2- diones) can isomerize to p-quinone methides (4-alkyl-2,5-cyclohexadien-1- one) at rates which depend on the type of substituent at the para position [Iverson, S. L., Hu, L. Q., Vukomanovic, V., and Bolton, J. L. (1995) Chem. Res. Toxicol. 8, 537-544]. In the present investigation, we explored the mechanism of this isomerization reaction using 4-propyl-3,5-cyclohexadiene- 1,2-dione (PQ) and its benzyl dideuterio analog 4-(1',1'-dideuteriopropyl)- 3,5-cyclohexadiene-1,2-dione (DPQ). The results show that the isomerization reaction is general base-catalyzed, which suggests that amino acids on proteins with basic side chains could catalyze the reaction in vivo. The Bronsted β value was determined to be 0.23 ± 0.02, consistent with the transfer of a proton in the rate-determining step. The rate/pH profile generated from the buffer dilution plots showed dependence on hydroxide ion concentration from pH 7.8 to 9, indicative of base catalysis. From pH 6 to 7.8, the reaction was independent of pH, suggesting that other processes compete at low buffer concentration in this pH region. Substitution of the benzyl CH2 group with CD2 dramatically slows the isomerization reaction. The kinetic deuterium isotope effect on quinone methide formation was determined by measuring the amount of quinone methide trapped as GSH conjugates from PQ compared with DPQ. The isotope effect on product formation was 5.5 ± 0.6, 37 °C. These data provide further evidence that formation of these electrophilic quinone methides from o-quinones could be catalyzed by basic residues in vivo and that the reaction could be inhibited by deuterium substitution at the benzyl methylene group.
Bolton,Hao Ming Wu,Li Qing Hu
p. 109 - 113
(2007/10/03)

Oxidation of Aromatic Compounds. IV. Oxidation of Symmetrical Diarylacetylenes in the CF3COOH-CH2Cl2-PbO2 System. A New One-Pot Synthesis of 1,2,3,4-Tetraaryl-2-butene-1,4-diones
Oxidation of symmetrical diarylacetylenes in the CF3COOH-CH2Cl2-PbO2 system (0-20 deg C, 1-3 h) yields 1,2,3,4-tetraaryl-2-butene-1,4-diones.According to (1)H NMR and GC-MS data the compounds synthesized have Z configuration.
Rudenko, A. P.,Vasil'ev, A. V.
p. 1360 - 1379
(2007/10/03)

KINETICS AND MECHANISM OF CLEAVAGE OF MODEL 2-AROXYALKYLAROMATIC STRUCTURES OF LIGNIN UNDER THE ACTION OF ANTHRAHYDROQUINONE IN ALKALINE MEDIUM
The kinetic and activation parameters of the cleavage of interunit alkylaryl ether bonds of lignin under conditions of caustic anthraquinone digestion have been determined using α-carbonyl nonphenolic model compounds.The values of the activation energy and reaction entropy indicate the bimolecular character of the reaction of anthrahydroquinone with carbonyl structures.Based on the results obtained, we advance a hypothesis on the active participation of the non-phenolic structure of lignin in the process of delignification under caustic anthraquinone digestion.
Maiorova, E. D.,Platonov, A. Yu.,Evstigneev, E. I.,Chistokletov, V. N.
p. 959 - 963
(2007/10/02)

AN EFFICIENT METHOD FOR THE SYNTHESIS OF 1-ARYLALKYNES
1-Arylalkynes are prepared from propiophenones in good yield via the sequence a) 2 equiv PCl5/Δ b) DBN or Δ and c) Mg metal.
Engler, Thomas A.,Combrink, Keith D.,Ray, James E.
p. 1735 - 1744
(2007/10/02)

Cyclization of Diketones to Pyridazine and Furan Derivatives
Condensation of (+/-)-2,3-bis(3,4-dimethoxybenzoyl)butane-1,4-dione 1 with different hydrazine bases afforded the corresponding pyridazines 2 and 3.Refluxing the diketone 1 with methanolic hydrogen chloride yielded the corresponding 3,4-dimethylfuran derivative 5.Reaction of acetonylacetone 6 with p-sulfamylphenylhydrazine afforded the corresponding 3,6-dimethyl-1H-pyridazine derivative 7.Reaction of 7 with the appropriate isocyanate and isothiocyanate yielded the corresponding benzenesulfonylurea 8 and thiourea 9 derivatives respectively.The structures of the compounds synthesized were affirmed by microanalyses and spectral studies.
Allah, Hassan M. Faid,Soliman, Raafat
p. 1745 - 1748
(2007/10/02)

Reaction of some N-acyl-1-alkylamines with polyphosphoric ester PPE: nuclear magnetic resonance and stereochemistry of reaction products
Phenylindanes were obtained from the reaction of N-acyl-1-arylalkylamines with polyphosphoric ester (PPE). cis-1-Methyl-3-(3,4-dimethoxyphenyl)-5,6-dimethoxyindane was synthesized to determine which stereoisomer was produced by N-formyl and N-acetyl-1-(3,4-dimethoxyphenyl)ethylamine with PPE.Nuclear magnetic resonance specta (1H and 13C) of several mono-, 1,3-di-, and 1,2,3-tri-substituted indanes were fully analyzed to provide information on steric interactions and conformation of the cyclopentene ring.Possible cyclodimerization pathways are proposed.
Alesso, Elba N.,Tombari, Dora G.,Iglesias, Graciela Y. Moltrasio,Aguirre, Jose M.
p. 2568 - 2574
(2007/10/02)

2-Phenylindenes: Development of a new mammary tumor inhibiting antiestrogen by combination of estrogenic side effect lowering structural elements
A new antiestrogenic, mammary tumor inhibiting 2-phenylindene was developed by the use of structural elements that we have shown to decrease estrogenic side effects but to increase antiestrogenic activity and retain the antitumor effect of certain stilben
Schneider,Ball
p. 75 - 79
(2007/10/02)

The E.S.R. Spectra of Cation Radicals Derived from Phenethyltetrahydroisoquinoline Ethers and Model Compounds
Cation radicals derived from the title compounds by oxidation with thallium tristrifluoroacetate have been characterized.The structures assigned to these radicals suggest that initial oxidation occures at the phenethyl ring in the compounds examined.Oxidation of homolaudanosine in this way gave the expected homoaporphine.
Hewgill, Frank R.,Pass, Michael C.
p. 555 - 563
(2007/10/02)

SYNTHESIS OF METABOLIC INTERMEDIATES OF DIETHYLSTILBESTROL
This report details the synthesis of 1) 3,4,4'-trihydroxy-α,α'-diethyl-trans-stilbene; 2) 3,4-bis-(p-hydroxyphenyl)-trans-3-hexenol; 3) 3,4-bis-(p-hydroxyphenyl)-2,4-cis,cis-hexadienol; 4) 3,4-bis-(3'-methoxy-4'-hydroxyphenyl)-trans-3-hexene; 5) 3,4-bis-(3',4'-dimethoxyphenyl)-trans-3-hexene.These compounds are suspected metabolites of diethylstilbestrol.
Hill, Kenneth A.,Peterson, Dorothy M.,Damodaran, Kalyani M.,Rao, P. Narasimha
p. 327 - 344
(2007/10/02)