- H2O2-mediated room temperature synthesis of 2-arylacetophenones from arylhydrazines and vinyl azides in water
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An environmentally benign, cost-efficient and practical methodology for the room temperature synthesis of 2-arylacetophenones in water has been discovered. The facile and efficient transformation involves the oxidative radical addition of arylhydrazines with α-aryl vinyl azides in the presence of H2O2 (as a radical initiator) and PEG-800 (as a phase-transfer catalyst). From the viewpoint of green chemistry and organic synthesis, the present protocol is of great significance because of using cheap, non-toxic and readily available starting materials and reagents as well as amenability to gram-scale synthesis, which provides an attractive strategy to access 2-arylacetophenones.
- Luo, Mengqiang,Zhang, Yaohong,Fang, Ping,Li, Yan,Qi, Chenze,Li, Yong,Shen, Runpu,Cheng, Kai,Wang, Hai
-
supporting information
p. 630 - 635
(2022/02/01)
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- Aerobic oxygenation of α-methylene ketones under visible-light catalysed by a CeNi3complex with a macrocyclic tris(salen)-ligand
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A hetero-tetranuclear CeNi3 complex with a macrocyclic ligand catalysed the aerobic oxygenation of a methylene group adjacent to a carbonyl group under visible-light radiation to produce the corresponding α-diketones. The visible-light induced homolysis of the Ce-O bond of a bis(enolate) intermediate is proposed prior to aerobic oxygenation.
- Fujiwara, Sakiko,Kon, Yoshihiro,Mashima, Kazushi,Nagae, Haruki,Okuda, Jun,Sakamoto, Kazutaka,Sato, Kazuhiko,Schindler, Tobias
-
supporting information
p. 11169 - 11172
(2021/11/04)
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- Visible-Light-Promoted [3 + 2] Cycloaddition of 2H-Azirines with Quinones: Access to Substituted Benzo[f]isoindole-4,9-diones
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A visible-light-promoteded [3 + 2] cycloaddition reaction of 2H-azirines with quinones has been developed under mild reaction conditions. The reaction provides a general and efficient strategy for the synthesis of the benzo[f]isoindole-4,9-diones scaffold
- Li, Lei,Liu, Chuang,Sun, Ran,Wang, He,Wang, Lijia,Wang, Xin,Zhou, Ming-Dong
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supporting information
(2022/01/22)
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- Palladium-catalyzed synthesis of α-aryl acetophenones from styryl ethers and aryl diazonium saltsviaregioselective Heck arylation at room temperature
-
Preparation of α-aryl acetophenones from styryl ethers and aryldiazonium salts is described. The reaction is catalyzed by palladium acetate at room temperature in the absence of ligand and base. The developed method is highly attractive in terms of reaction conditions, substrate scope, functional group tolerance and yields. Synthetic applications of the present method are demonstrated by preparing α-aryl indoles and 3-aryl isocoumarin from styryl ethers.
- Kandasamy, Jeyakumar,Lee, Yong Rok,Singh, Adesh Kumar,Venkatesh, Rapelly
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supporting information
p. 7832 - 7837
(2021/09/28)
-
- Oxaprozin Analogues as Selective RXR Agonists with Superior Properties and Pharmacokinetics
-
The retinoid X receptors (RXR) are ligand-activated transcription factors involved in multiple regulatory networks as universal heterodimer partners for nuclear receptors. Despite their high therapeutic potential in many pathologies, targeting of RXR has only been exploited in cancer treatment as the currently available RXR agonists suffer from exceptional lipophilicity, poor pharmacokinetics (PK), and adverse effects. Aiming to overcome the limitations and to provide improved RXR ligands, we developed a new potent RXR ligand chemotype based on the nonsteroidal anti-inflammatory drug oxaprozin. Systematic structure-activity relationship analysis enabled structural optimization toward low nanomolar potency similar to the well-established rexinoids. Cocrystal structures of the most active derivatives demonstrated orthosteric binding, and in vivo profiling revealed superior PK properties compared to current RXR agonists. The optimized compounds were highly selective for RXR activation and induced RXR-regulated gene expression in native cellular and in vivo settings suggesting them as excellent chemical tools to further explore the therapeutic potential of RXR.
- Schierle, Simone,Chaikuad, Apirat,Lillich, Felix F.,Ni, Xiaomin,Woltersdorf, Stefano,Schallmayer, Espen,Renelt, Beatrice,Ronchetti, Riccardo,Knapp, Stefan,Proschak, Ewgenij,Merk, Daniel
-
supporting information
p. 5123 - 5136
(2021/05/04)
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- The organocatalytic enantiodivergent fluorination of β-ketodiaryl-phosphine oxides for the construction of carbon-fluorine quaternary stereocenters
-
Commercially available cinchona alkaloids that can catalyze the enantiodivergent fluorination of β-ketodiarylphosphine oxides were developed to construct carbon-fluorine quaternary stereocenters. This protocol features a wide scope of substrates and excellent enantioselectivities, and it is scalable.
- Xie, Shaolei,He, Zhi-Juan,Zhang, Ling-Hui,Huang, Bo-Lun,Chen, Xiao-Wei,Zhan, Zong-Song,Zhang, Fu-Min
-
supporting information
p. 2069 - 2072
(2021/03/01)
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- Ring size and nothing else matters: unusual regioselectivity of alkyne hydration by NHC gold(i) complexes
-
We have investigated the role of ring sizes and substituents in NHC ligands in some (NHC)Au(i) complexes in the hydration of internal alkynes. Despite the fact that using (NHC)Au(i) complexes in the hydration of diarylacetylenes leads to Markovnikov-type products, the precise tuning of ligands allows changing the regioselectivity in arylalkylacetylene hydration to the anti-Markovnikov-type.
- Ageshina, Alexandra A.,Asachenko, Andrey F.,Chesnokov, Gleb A.,Minaeva, Lidiya I.,Nechaev, Mikhail S.,Philippova, Anna N.,Rzhevskiy, Sergey A.,Topchiy, Maxim A.
-
supporting information
p. 5686 - 5689
(2021/06/16)
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- Synthesis of unsymmetrical ketones by applying visible-light benzophenone/nickel dual catalysis for direct benzylic acylation
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Herein, we report a dual catalytic system for the direct benzylic C-H acylation reaction furnishing a variety of unsymmetrical ketones. A benzophenone-derived photosensitizer combined with a nickel catalyst has been established as the catalytic system. Both acid chlorides and anhydrides are able to acylate the benzylic position of toluene and other methylbenzenes. The method offers a valuable alternative to late transition metal catalyzed C-H acylation reactions.
- Krach, Patricia E.,Dewanji, Abhishek,Yuan, Tingting,Rueping, Magnus
-
supporting information
p. 6082 - 6085
(2020/06/18)
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- Mn/Cu catalyzed addition of arylboronic acid to nitriles: Direct synthesis of arylketones
-
A direct and efficient synthesis of arylketones via arylboronic acid addition to nitriles in presence of inexpensive Mn/Cu catalytic system is reported. The use of non-precious Mn and Cu salts has been found to be highly advantageous both in terms of accessibility as well as cost effectiveness. A series of arylboronic acids as well as nitriles were used to synthesize a variety of symmetrical and unsymmetrical arylketones. Based on the literature studies, the reaction mechanism is anticipated to go through an aryl radical intermediate which reacted with the copper activated nitrile to give the desired arylketones after the hydrolysis of the imine intermediate.
- Moustafa, Dina,Sweet, Chelsea,Lim, Hyun,Calalpa, Brenda,Kaur, Parminder
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p. 3816 - 3820
(2018/09/18)
-
- COMPOUNDS
-
The present invention describes non-cyclic enaminoketone compounds and their applications relating to absorption electromagnetic energy, in particular UV radiation.
- -
-
Paragraph 00137
(2017/08/01)
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- Novel bisamide palladium(II) pincer complexes: effective catalysts in α-arylation of ketones
-
Three benzenedicarboxamide ligands (L) were designed and synthesized, and each was used to prepare a palladium(II) complex Pd(L)Br and Pd(L)(OAc). These NCN pincer complexes were used to catalyze the α-arylations of a variety of ketones with aryl chlorides or bromides in various solvents, and moderate-to-excellent yields were obtained (up to 95%). Further research showed that unactivated and sterically hindered aryl halides and ketones are also suitable substrates for the synthesis of α-arylation. Graphical Abstract: [Figure not available: see fulltext.].
- Kai, Wang,Liu, Dabin,Qian, Hua,Ye, Zhiwen
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p. 443 - 450
(2017/07/12)
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- Metal-free synthesis of ketones by visible-light induced aerobic oxidative radical addition of aryl hydrazines to alkenes
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A green and cost-effective method has been developed for the conversion of alkenes to ketones under metal-free conditions. The reaction involves the oxidative addition of alkenes with aryl radicals, which are generated by visible-light induced aerobic oxidation of arylhydrazines. The key features of this reaction include broad substrate scope, readily available reagents and amenability to gram-scale synthesis.
- Ding, Ya,Zhang, Wenkai,Li, Hao,Meng, Yunge,Zhang, Te,Chen, Qiu-Yun,Zhu, Chunyin
-
supporting information
p. 2941 - 2944
(2017/07/24)
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- Light-Driven Carboxylation of o-Alkylphenyl Ketones with CO2
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o-Alkylphenyl ketones undergo a C-C bond forming carboxylation reaction with CO2 simply upon irradiation with UV light or even solar light. The reaction presents a clean process exploiting light energy as the driving force for carboxylation of organic molecules with CO2.
- Masuda, Yusuke,Ishida, Naoki,Murakami, Masahiro
-
supporting information
p. 14063 - 14066
(2015/11/25)
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- A Remarkably Simple Hybrid Surfactant-NHC Ligand, Its Gold-Complex, and Application in Micellar Catalysis
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A combination of an N-heterocyclic carbene (NHC) ligand and a structurally simple surfactant has been realized, the hybrid surfactant-NHC. The related gold complex was synthesized, fully characterized, and applied in catalysis. This remarkably simple strategy allows, in combination with a co-surfactant, the application of gold catalysis in water. Just merge it! The hybrid of a surfactant and an N-heterocyclic carbene (NHC) ligand is reported and applied for the synthesis of the derived gold complex (see scheme). The new resulting NHC-based metallosurfactant can interact with surfactants to form micelles and allows micellar catalysis for gold catalysis in water.
- Rühling, Andreas,Galla, Hans-Joachim,Glorius, Frank
-
supporting information
p. 12291 - 12294
(2015/08/25)
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- Ascorbic Acid Promoted Oxidative Arylation of Vinyl Arenes to 2-Aryl Acetophenones without Irradiation at Room Temperature under Aerobic Conditions
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A convenient and general protocol for oxidative arylation of vinyl arenes by aryl radicals generated in situ from arene diazonium fluoroborates promoted by ascorbic acid in air at room temperature has been developed in the absence of any additive and visible light irradiation. A series of diversely substituted 2-aryl acetophenones have been obtained in good yields by this procedure.
- Majhi, Biju,Kundu, Debasish,Ranu, Brindaban C.
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supporting information
p. 7739 - 7745
(2015/08/18)
-
- COMPLEXES OF PHOSPHINE LIGANDS COMPRISING A CARBA-CLOSO-DODECABORATE SUBSTITUENT
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This invention relates to complexes comprising phosphine ligands comprising a carbo-closo-dodecaborate substituent and transition metals as well as their use in catalytic reactions.
- -
-
Paragraph 0164; 0165
(2014/05/24)
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- Diarylated ethanones from Mo(CO)6-mediated and microwave-assisted palladium-catalysed carbonylative Negishi cross-couplings
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Two protocols for palladium-catalysed carbonylative Negishi cross-couplings were developed for aryl iodides and aryl bromides. The two main breakthroughs were that molybdenum hexacarbonyl [Mo(CO)6] could be used as a solid in situ source of CO, and that controlled microwave irraditaion could be used for heating. Consequently, the reactions were safe (in contrast to when CO gas was used) and fast (in comparison to when conventional heating was used). The carbonylative cross-coupling reactions were carried out using commercially available benzylzinc bromide in closed vials (90-120°C for 0.5-1 h) to give a set of diarylated ethanones, a common pharmacophore found in several pharmaceuticals, in moderate to high isolated yields (47-84 %). The mild three-component carbonylation protocol presented here is operationally simple, safe, and rapid, and the formation of the carbonylative Negishi cross-coupling product is favoured over the product of Negishi cross-coupling. Copyright
- Motwani, Hitesh V.,Larhed, Mats
-
supporting information
p. 4729 - 4733
(2013/08/23)
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- Palladium-catalyzed carbonylative negishi-type coupling of aryl iodides with benzyl chlorides
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Do the competition: The synthesis of 1,2-diarylethanones has been accomplished using the palladium-catalyzed coupling of aryl iodides and CO/benzyl chlorides or benzoyl chlorides. These reactions proceed smoothly in the presence of zinc powder to afford the products in moderate to excellent yields.
- Wu, Xiao-Feng,Schranck, Johannes,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 40 - 44
(2012/03/11)
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- Arylation of α-pivaloxyl ketones with arylboronic reagents via Ni-catalyzed sp3 C-O activation
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A Suzuki-Miyaura coupling of α-pivaloxyl ketones via Ni-catalyzed sp3 C-O activation to produce α-aryl ketones is developed. This study offers a convenient method to construct α-arylation products from readily available α-hydroxyl carbonyl compounds.
- Huang, Kun,Li, Gang,Huang, Wei-Ping,Yu, Da-Gang,Shi, Zhang-Jie
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p. 7224 - 7226
(2011/08/09)
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- Addition of arylboronic acids to nitriles in aqueous media catalyzed by a 2,2′-bipyridine-cyclopalladated ferrocenylimine complex
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The addition of arylboronic acids to nitriles catalyzed by a bipyridine-cyclopalladated ferrocenylimine complex in aqueous media was developed. The reactions could be conducted under acidic or basic conditions in aqueous media. The addition of NH4Cl was found to have a drastic effect on the reaction yields. Georg Thieme Verlag Stuttgart.
- Yu, Ajuan,Li, Jingya,Cui, Mengjun,Wu, Yangjie
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p. 3063 - 3067
(2008/03/12)
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- Heck reactions of α- or β-substituted enol ethers with aryl bromides catalysed by a tetraphosphane/palladium complex - Direct access to acetophenone or 1-arylpropanone derivatives
-
cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphanylmethyl)cyclopentane/ [PdCl(C3H5)]2 efficiently catalyses the Heck reaction of α- and β-substituted enol ethers with aryl bromides. The arylation of 1-phenyl-1-(trimethylsilyloxy) ethylene led directly to the 2-aryl-1-phenylethanones. Similar reaction rates were observed with electron-rich, electron-deficient or sterically congested aryl bromides. Heck reaction with benzyl isopropenyl ether gave a mixture of isomers. However, this mixture gave selectively the 1-arylpropanones after hydrolysis. Employing β-methoxystyrene, 3-ethoxyacrylonitrile or methyl 3-methoxyacrylate, the regioselective α-arylation of these enol ethers was observed in all cases, but mixtures of (Z) and (E) isomers were generally obtained, which in many cases yielded a single ketone product after acid treatment. The stereoselectivity of this reaction depends on steric and electronic factors, and better stereoselectivities in favour of (Z) isomers were observed with electron-rich or sterically congested aryl bromides. Higher yields were obtained for this reaction with electron-rich or sterically congested aryl bromides than with electron-poor aryl bromides. These observations suggest that the rate-limiting step of the catalytic cycle is not the oxidative addition of the aryl bromide to the palladium complex with these substituted enol ethers. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Battace, Ahmed,Feuerstein, Marie,Lemhadri, Mhamed,Zair, Touriya,Doucet, Henri,Santelli, Maurice
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p. 3122 - 3132
(2008/02/08)
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- Heck reactions of 2-substituted enol ethers with aryl bromides catalysed by a tetraphosphine/palladium complex
-
cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/ [PdCl(C3H5)]2 efficiently catalyses the Heck reaction of β-substituted enol ethers with aryl bromides. Employing β-methoxystyrene, 3-ethoxyacrylonitrile or methyl 3-methoxyacrylate, the regioselective α-arylation of these enol ethers was observed in all cases, and mixtures of Z and E isomers were generally obtained, which in many cases yielded a single ketone product after acid treatment. The stereoselectivity of this reaction depends on steric and electronic factors, and better stereoselectivities in favour of Z isomers were observed with electron-rich or sterically congested aryl bromides. Better yields were obtained for this reaction with electron-rich or sterically congested aryl bromides than with electron-poor aryl bromides. This observation suggests that with these β-substituted enol ethers the rate-limiting step of the catalytic cycle is not the oxidative addition of the aryl bromide to the palladium complex.
- Battace, Ahmed,Zair, Touriya,Doucet, Henri,Santelli, Maurice
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p. 459 - 462
(2007/10/03)
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- Photochemical preparation of highly functionalized 1-indanones
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A series of o-alkylphenyl alkyl ketones 1 were synthesized by different methods. The presence of a leaving group X adjacent to the carbonyl group is the special peculiarity of these ketones. Upon irradiation the keto carbonyl group of these compounds undergoes an n-π* excitation followed by a 1,5-hydrogen migration from the o-alkyl substituent to the carbonyl oxygen atom. The thus formed 1,4-diradicals are subject to a very rapid elimination of acid HX, giving 1,5-diradicals. We called this process spin center shift. After intersystem crossing these diradicals cyclize to 1-indanones 20 in good yields. Depending on the solvent and on substituents, o-alkoxyalkyl ketones 22 or benzo-[c]furanes 21 are obtained as byproducts. The mechanism of the cyclization was elucidated by quantum chemical calculations and kinetic measurements.
- Wessig, Pablo,Glombitza, Clemens,Mueller, Gunnar,Teubner, Janek
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p. 7582 - 7591
(2007/10/03)
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- Alkali metal ion controlled product selectivity during photorearrangements of 1-naphthyl phenyl acylates and dibenzyl ketones within zeolites
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Photochemical behaviors of 1-naphthyl phenyl acylates and dibenzyl ketones included in zeolites have been compared. 1-Naphthyl phenyl acylates while in solution produce eight photoproducts; within NaY it gives a single product. The selectivity is attributed to the restriction brought on the mobility of the primary radical pair by the alkali metal ions present in zeolites. Photochemistry of dibenzyl ketones within NaY reveals that the intersystem crossing in caged radical pairs could be influenced by the heavy alkali metal ions. Structures of complexes among Li+ ion and the guest 1-naphthyl phenyl acetates and dibenzyl ketone computed at the B3LYP level have been useful to understand the origin of the observed product selectivity within zeolites.
- Warrier,Kaanumalle, Lakshmi S.,Ramamurthy
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p. 620 - 631
(2007/10/03)
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- A simple, user-friendly process for the homologation of aldehydes using tosylhydrazone salts
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Aldehydes can be homologated to ketones in moderate to good yields using aryldiazomethanes generated in situ from tosylhydrazones. Chiral aldehydes can be employed with almost complete retention of configuration. The tosylhydrazones can also be generated in situ from the corresponding aldehyde leading to a one-pot process for coupling two different carbonyl compounds to give ketones. (C) 2000 Elsevier Science Ltd.
- Aggarwal, Varinder K.,De Vicente, Javier,Pelotier, Beatrice,Holmes, Ian P.,Bonnert, Roger V.
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p. 10327 - 10331
(2007/10/03)
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- Heavy cation effect on intersystem crossing between triplet and singlet phenylacyl and benzyl geminate radical pairs within zeolites
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The difference in product selectivity observed between dibenzyl ketones and naphthyl esters in zeolites is due to the difference in spin of the radical pairs formed from these precursors. Heavy cations present in zeolites can enhance intersystem crossing between triplet and singlet geminate radical pairs. (C) 2000 Elsevier Science Ltd.
- Warrier,Turro,Ramamurthy
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p. 7163 - 7167
(2007/10/03)
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- Role of water in intrazeolite photochemistry
-
The photochemical and photophysical behavior of several ketones included within Na X zeolites is dependent upon the adsorbed water within the zeolite. Results suggest that when the zeolite is dry (water free), the guest ketones reside within supercages and when the internal structure is filled with water the guest molecules are displaced to the external surface.
- Zhang,Turro,Johnston,Ramamurthy
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p. 4861 - 4864
(2007/10/03)
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- Friedel-Crafts Acylation of Arenes Catalysed by Bromopentacarbonylrhenium(I)
-
The intermolecular Friedel-Crafts acylation of aromatic compounds (such as toluene, m-xylene, and anisole) with various acid chlorides proceeds by using a catalytic amount of bromopentacarbonylrhenium(I) to afford aryl ketones.Intramolecular acylation is also catalyzed by the above-mentioned catalyst to give indanone and tetralone derivatives.
- Kusama, Hiroyuki,Narasaka, Koichi
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p. 2379 - 2384
(2007/10/03)
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- A Comparsion between Zeolite-Solvent Slurry and Dry Solid Photolyses
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The use of zeolite-solvent slurry as a convenient medium to carry out photoreactions is illustrated with four examples, namely Norrish type I reaction of dibenzyl ketones, Norrish type I and type II reactions of α-alkylbenzyl benzyl ketones, Norrish type II reaction of aryl alkyl ketones, and photodimerization of acenaphthylene.Solvent present within the supercages of zeolites X and Y provides constraint on the mobility of the included guest molecules.Such restrictions are reflected in the product distributions.The difference in the product distribution obtained between the zeolite-solvent slurry and a homogeneous solution is often higher than that between the dry powder zeolites and a homogeneous solution.
- Ramamurthy, V.,Corbin, D. R.,Turro, N. J.,Zhang, Z.,Garcia-Garibay, M. A.
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p. 255 - 261
(2007/10/02)
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- Torsionally and Hydrophobically Modified 2,3-Diarylindenes as Estrogen Receptor Ligands
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2,3-Diarylindenes are ligands for the estrogen receptor which display intrinsic fluorescence.In order to optimize the receptor binding affinity of these compounds while preserving their desirable fluorescence properties, a series of torsionally modified analogues were prepared.A fluorine or methyl group was introduced on either of the two phenyl substituents ortho to their attachment site to the indene nucleus, in order to increase the out-of-plane twist of the appended rings.The analogues were prepared by the benzylation of appropriate deoxybenzoins, followed by Friedel-Crafts cyclic alkylation-dehydration.Comparison of the X-ray crystal structure of one analogue with unsubstituted analogues confirms the torsional perturbation effected by the ortho substituent.The torsional disposition of the C-2 aryl group in the substituted diphenylindenes is further investigated by UV (absorbance maxima and molar absorptivities), fluorescence (Stokes' shift), and NMR (chemical shifts).These spectroscopic measurements indicate increasing twisting between the C-2 aryl substituent and the indene system according to the following order: 3-ring o-Me-indene 9f diphenylindene 15 = 20 deg 3-ring o-F-indene 9c 1-Me-indene 16 2-ring o-F-indene 9b 2-ring o-Me-indene 9e = 63 deg.The binding affinity of these analogues to the estrogen receptor was evaluated by a competitive radiometric receptor binding assay.While o-fluoro or o-methyl substitution on the 3-ring increases binding only slightly, binding of the o-fluoro 2-ring analogue is increased ca. 6-fold and the o-methyl analogue 11-fold, giving, in the latter case, a compound with an affinity equivalent to that of estradiol.The increase in binding affinity afforded by ortho substitution correlates with the increase in the torsion angle of the C-2 aryl ring.A thermodynamic evaluation of the receptor fit (Andrews, P.R.; Craik, D.J.; Martin, J.L.J.Med.Chem. 1984, 27, 1648) indicates that, for the o-methyl-2-ring analogue, the effect of the ortho substitution on increasing receptor binding appears to be a combination of increased surface area due to the substituent itself, together with a change in surface area of the ligand that results from the increased torsion of the two aryl rings.An o-fluoro substituent on the 2-ring provides a compromise between the relative planarity required for high fluorescence intensity and the molecular shape needed for increased estrogen receptor binding affinity. o-Methyl, o-fluoro, and p-methyl substitution of the 3-ring have no value in the development of a fluorescent, higher affinity 2,3-diarylindene.
- Anstead, Gregory M.,Peterson, Chad S.,Pinney, Kevin G.,Wilson, Scott R.,Katzenellenbogen, John A.
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p. 2726 - 2734
(2007/10/02)
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- MAGNETIC ISOTOPE AND MAGNETIC FIELD EFFECTS ON THE PRODUCT DISTRIBUTIONS OF PHOTOLYSES OF DIBENZYL KETONE ADSORBED ON ZEOLITES
-
The photolysis of dibenzyl ketone adsorbed on faujasite zeolites results in product distributions that depend on the cation density and cation type, and, in two cases, were significantly modified by magnetic effects.
- Turro, Nicholas J.,Zhang, Zhenyu
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p. 3761 - 3764
(2007/10/02)
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- Photochemistry of Molecules Adsorbed on Alkali Ion Exchanged Zeolites. A "Lebensraum" Effect on Product Formation.
-
The products of the photolysis of dibenzyl ketone adsorbed on faujasite zeolites are found to be a strong function of the Si/Al composition of the zeolite and of the exchangeable cations associated with the internal framework.
- Turro, Nicholas J.,Zhang, Zhenyu
-
p. 5637 - 5640
(2007/10/02)
-
- In-Situ Diffuse Reflectance Infrared Spectroscopic Study of the Photodecomposition of Dibenzyl Ketone Adsorbed on Zeolites
-
The infrared spectra of 1,3-diphenyl-2-propanone (dibenzyl ketone, DBK) adsorbed on the hydrophobic zeolite Silicalite have been measured by diffuse reflectance techniques.These spectra are consident with the existence of several classes of adsorption/inclusion sites in the Silicalite framework; in accord with previous studies, two main classes of sites are discernible.The photodecomposition of included dibenzyl ketone was followed directly by in-situ UV photolysis.The formation of products can be followed directly from the infrared spectra.The results demonstrate that the photodecomposition of included DBK proceeds preferentially in one class of sites which are tentatively assigned to channel inclusion as opposed to surface adsorption sites.
- Yang, P. W.,Casal, H. L.
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p. 2422 - 2424
(2007/10/02)
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- Surface photochemistry: generation of benzyl radical pairs on dry silica gel
-
Singlet and triplet benzyl radical pairs have been generated on silica gel by photolysis of a benzyl phenylacetate, a dibenzyl ketone, and a dibenzyl sulfone.The extent of geminate radical recombination has been measured and requires that translational motion of radicals occur on the silica gel surface.This motion was affected by the radical pair multiplicity and the photolysis temperature, but was relatively insensitive to the state of hydration of the silica gel and presence of coadsorbates.The presence of certain rearranged starting materials, which are not formed in solution , amongst the products from photolysis of both dibenzyl ketone and dibenzyl sulfone on silica gel indicates the restrictions on radical movement on the surface on the shorter timescale of the benzyl-phenylacetyl and -benzyl - benzyl sulfonyl radical pairs.
- Frederick, Bradley,Johnston, Linda J.,Mayo, Paul de,Wong, S. King
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p. 403 - 410
(2007/10/02)
-
- Photochemistry of chloro-2-vinylstilbenes
-
Short irradiation at 300 nm of α-chloro- and β-chloro-2-vinylstilbene (20 and 21) leads to a mixture of 2-vinyltolane (35) and 2-vinylstilbene (1) accompanied by the cis- and trans-isomers of the starting compounds.Evidence is found for the occurrence of an ionic intermediate during the photolysis of 20 in methanol.At 360 nm, an additional, small amount of 1-chloro-endo- and 1-chloro-exo-6-phenylbenzobicyclohex-2-ene (39) is formed formed from 20.The elimination of hydrogen chloride also occurs during the irradiation of 2-(2-chlorovinyl)stilbene (23) and leads to 2-ethynylstilbene (41).The acetylenic compounds are photocyclized into 2-phenylnaphthalene (38).However, 2-(1-chlorovinyl)stilbene (22) reacts without loss of chlorine to give 1-chloro-exo-5-phenylbenzobicyclo-hex-2-ene (40).This exceptional reaction mode is due to a much higher rate of photocyclization resulting from less distortion in the stilbene moiety and a preference for a conformation better suited to the reaction of the 2-(1-chlorovinyl)stilbene molecule.It is shown that both isomers of 22 can photocyclize into 40.
- Brouw, P. M. op den,Laarhoven, W. H.
-
-
- DESOXYBENZOINS FROM THE LITHIUM BROMIDE-CATALYZED HOMOLOGATION OF AROMATIC ALDEHYDES WITH PHENYLDIAZOMETHANE
-
Desoxybenzoins are obtained in good to excellent yields from the lithium bromide-catalyzed homologation of aromatic aldehydes with phenyldiazomethane.
- Loeschorn, Carol A.,Nakajima, Masayuki,Anselme, Jean-Pierre
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p. 985 - 986
(2007/10/02)
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- The Synthesis of 2-(5-Phenylthiazol-4-yl)benzoic Acids
-
The four-step synthesis of 2-(5-phenylthiazol-4-yl)benzoic acid (2a), and its 2-amino derivatives (2b), required for testing as potential plant growth regulators, is described.The α-bromo ketone (9b) was conveniently prepared from commercially available 3
- Teitei, Tsutomu
-
p. 605 - 611
(2007/10/02)
-