- H2O2-mediated room temperature synthesis of 2-arylacetophenones from arylhydrazines and vinyl azides in water
-
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)
-
- 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
-
supporting information
p. 7832 - 7837
(2021/09/28)
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- Azobenzene-Semicarbazone Enables Optical Control of Insect Sodium Channels and Behavior
-
Photopharmacology uses molecular photoswitches to establish control over the action of bioactive molecules. The application of photopharmacology in the research of invertebrate sodium channels has not been investigated. Here we report several photochromic ligands of metaflumizone. One ligand, termed ABM04, underwent reversible trans-cis isomerization under ultraviolet or blue light irradiation. cis-ABM04 had excellent larvicidal activity against mosquito larvae with an LC50 value of 4.39 μM and showed insecticidal activity against Mythimna separata with an LC50 value of 7.19 μM. However, trans-ABM04 was not found to have biological activity. ABM04 (10 μM) can induce depolarization of dorsal unpaired median neurons and enable the real-time photoregulation of mosquito larval behavior. The precise regulation of invertebrate sodium channels is realized for the first time, which provides a new strategy for the basic and accurate research of invertebrate sodium channels.
- Chen, Ruijia,Fu, Wen,Li, Zhong,Qiao, Zhi,Shao, Xusheng,Xu, Zhiping,Zhang, Yongchao
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p. 15554 - 15561
(2021/12/27)
-
- Heterogeneous visible-light-induced Meerwein hydration reaction of alkenes in water using mpg-C3N4 as a recyclable photocatalyst
-
A green and efficient visible light induced Meerwein hydration reaction of alkenes in aqueous medium using mpg-C3N4 as a recyclabe photocatalyst has been disclosed. This protocol provides a direct approach for the preparation of racemic alcohols via a free radical mechanism. Water acted as both a solvent and a reagent without any additives or co-solvents. The metal-free heterogeneous semiconductor is found to be fully recyclable at least 5 times without any significant reduction in activity. The Meerwein hydration reaction has an excellent substrate scope and gave the desired products in moderate to high yields. Furthermore, this reaction could be carried out under solar light irradiation and is applicable for large-scale reactions with satisfactory results.
- Wang, Jingjing,Xue, Linshuang,Hong, Mei,Ni, Bangqing,Niu, Tengfei
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p. 411 - 416
(2020/02/13)
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- Porphyrins as Photoredox Catalysts in Csp2-H Arylations: Batch and Continuous Flow Approaches
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We have investigated both batch and continuous flow photoarylations of enol-acetates to yield different α-arylated aldehyde and ketone building blocks by using diazonium salts as the aryl-radical source. Different porphyrins were used as SET photocatalysts, and photophysical as well as electrochemical studies were performed to rationalize the photoredox properties and suggest mechanistic insights. Notably, the most electron-deficient porphyrin (meso-tetra(pentafluorophenyl)porphyrin) shows the best photoactivity as an electron donor in the triplet excited state, which was rationalized by the redox potentials of excited states and the turnover of the porphyrins in the photocatalytic cycle. A two-step continuous protocol and multigram-scale reactions are also presented revealing a robust, cost-competitive, and easy methodology, highlighting the significant potential of porphyrins as SET photocatalysts.
- De Souza, Aline A. N.,Silva, Nathalia S.,Müller, Andressa V.,Polo, André S.,Brocksom, Timothy J.,De Oliveira, Kleber T.
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p. 15077 - 15086
(2019/01/03)
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- Merging visible-light photoredox and micellar catalysis: Arylation reactions with anilines nitrosated in situ
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An aqueous photocatalytic system was designed by merging visible-light photoredox catalysis with micellar catalysis. Eosin B, an organic dye, was utilized as the photocatalyst, and Triton X-100 was employed as the surfactant; both are inexpensive and commercially available. This clean and energy-saving catalytic system enables photocatalytic reactions of the diazonium ion generated in situ to proceed smoothly in water without any co-solvents or additives at room temperature.
- Bu, Mei-Jie,Lu, Guo-Ping,Jiang, Jianzhong,Cai, Chun
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p. 3728 - 3732
(2018/08/12)
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- Salicylic Acid-Catalyzed Arylation of Enol Acetates with Anilines
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α-Aryl ketones are both structure moieties commonly found in bioactive compounds and versatile synthetic intermediates for the preparation of drug-like molecules. An operationally simple and scalable protocol has been developed to prepare α-aryl ketones from readily available aromatic amines and enol acetates (or silyl enol ethers). This metal-free methodology features the use of salicylic acid as a convenient catalyst to promote the formation of aryl radicals from in-situ generated aryl diazonium salts, without demanding thermal or photochemical activation. The mild reaction conditions used are compatible with anilines substituted with diverse functionalities. Structural elaboration of some prepared α-aryl ketones was accomplished to illustrate their usefulness as building blocks. (Figure presented.).
- Felipe-Blanco, Diego,Gonzalez-Gomez, Jose C.
-
supporting information
p. 2773 - 2778
(2018/07/29)
-
- Method for synthesizing aminoquinoxaline mixture
-
The invention discloses a method for synthesizing a mixture of 2-(4-aminophenyl)-3-phenyl-6-aminoquinoxaline and 3-(4-aminophenyl)-2-phenyl-6-aminoquinoxaline. The method comprises the following steps: by taking 4-nitrophenylacetic acid as an initial mate
- -
-
Paragraph 0021; 0022; 0029; 0030; 0037; 0038
(2017/09/26)
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- Expanding the Hammett Correlations for the Vinylheptafulvene Ring-Closure Reaction
-
A selection of 2,3-diarylated photochromic dihydroazulenes (DHAs) was prepared by following two different protocols. The first protocol relies on the synthesis of a 3-bromo-substituted dihydroazulene, which is subjected to a Suzuki cross-coupling reaction
- Kilde, Martin Dr?hse,Hansen, Mia Harring,Broman, S?ren Lindb?k,Mikkelsen, Kurt V.,Nielsen, Mogens Br?ndsted
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p. 1052 - 1062
(2017/02/23)
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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)
-
- Visible-Light-Promoted Arylation Reactions Photocatalyzed by Bismuth(III) Oxide
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Bismuth(III) oxide has been successfully applied as a photocatalyst in the arylation of heteroarenes with diazonium salts. With a low catalyst loading (1 to 5 mol-%), this cheap and nontoxic semiconductor could efficiently promote the formation of the aryl radical under visible light irradiation. The arylated products are obtained in moderate to good yields, and the process admits straightforward scale-up (10 mmol; 1 mol-% Bi2O3). In two cases, the diazonium salt was generated in situ and used in the photocatalytic arylation in a tandem manner. Besides heteroarenes, Bi2O3 also catalyzed the arylation of differently substituted alkenes and alkynes, thus representing a viable and practical alternative to the more commonly used ruthenium complexes and organic dyes.
- Buglioni, Laura,Riente, Paola,Palomares, Emilio,Pericàs, Miquel A.
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supporting information
p. 6986 - 6990
(2017/12/26)
-
- Synthesis of 2-Benzylphenyl Ketones by Aryne Insertion into Unactivated C-C Bonds
-
A transition-metal-free procedure to access to functionalized 2-benzylphenyl ketones is described by direct insertion of arynes into benzylic C-C bonds. This reaction was promoted by cesium fluoride at room temperature, allowing the products to form in high selectivity and achieve good functional group tolerance.
- Rao, Bin,Tang, Jinghua,Zeng, Xiaoming
-
supporting information
p. 1678 - 1681
(2016/04/26)
-
- Copper-catalyzed base-accelerated direct oxidation of C-H bond to synthesize benzils, isatins, and quinoxalines with molecular oxygen as terminal oxidant
-
We describe herein an efficient and general copper (II)-catalyzed base-accelerated oxidation of the C-H bond to synthesize benzils and isatins. With similar oxidation system an efficient one-pot procedure for the synthesis of quinoxaline derivatives was realized. The two protocols feature using molecular oxygen as terminal oxidant, low catalyst loading, wide substrate scope, and high functional-group tolerance.
- Yu, Jing-Wen,Mao, Shuai,Wang, Yong-Qiang
-
supporting information
p. 1575 - 1580
(2015/03/14)
-
- URAZOLE COMPOUNDS
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The present invention relates to a compound of formula (I) or a stereoisomer, enantiomer, racemic, or tautomer thereof, (I) wherein R1, R2, R3, R4, R5, R6, R7, L1 and Q1 have the meaning defined in the claims and the description. The present invention also relates to a process for the preparation of the compound of formula (I). The present invention also relates to the use of a compound of formula (I) as an in situ precursor of a triazolinedione reagent for the functionalization of enes, dienes, aryl and heteroaryl systems via the ene reactions, Diels-Alder reactions, and electrophilic aromatic substitution reactions of said reagent. The present invention also relates to the use of a compound of formula (I) in polymers, membranes, adhesives, foams, sealants, molded articles, films, extruded articles, fibers, elastomers, polymer based additives, pharmaceutical and biomedical products, varnishes, paints, coatings, inks, composite material, organic LEDs, organic semiconductors, conducting organic polymers, or 3D printed articles. The present invention also relates to article comprising said compound of formula (I) and to a process for reshaping and/or repairing said article.
- -
-
Page/Page column 178
(2015/02/25)
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- An expedient route to heterocycles through α-arylation of ketones and arylamides by microwave induced thermal SRN1 reactions
-
Microwave irradiation promotes a quick aromatic nucleophilic substitution by a thermally induced electron transfer process to form new C-C bonds by the coupling of aryl radicals and enolate nucleophiles. Diverse 2-aryl-1- phenylethanones can be prepared by the direct α-arylation of acetophenone with different haloarenes. The ketone enolate anion is generated by deprotonation with tBuOK in DMSO and the reaction is carried out in a closed microwave vessel at 70-100°C for 10 min. This simple procedure also allows the synthesis of deoxybenzoin and indole heterocycle derivatives by inter- or intra-molecular ring closure reactions, with moderate to excellent substitution yields. This journal is the Partner Organisations 2014.
- Soria-Castro, Silvia M.,Caminos, Daniel A.,Penenory, Alicia B.
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p. 17490 - 17497
(2014/05/06)
-
- Opioid peptidomimetics: Leads for the design of bioavailable mixed efficacy μ opioid receptor (MOR) agonist/δ opioid receptor (DOR) antagonist ligands
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We have previously described opioid peptidomimetic, 1, employing a tetrahydroquinoline scaffold and modeled on a series of cyclic tetrapeptide opioid agonists. We have recently described modifications to these peptides that confer a μ opioid receptor (MOR) agonist, δ opioid receptor (DOR) antagonist profile, which has been shown to reduce the development of tolerance to the analgesic actions of MOR agonists. Several such bifunctional ligands have been reported, but none has been demonstrated to cross the blood-brain barrier. Here we describe the transfer of structural features that evoked MOR agonist/DOR antagonist behavior in the cyclic peptides to the tetrahydroquinoline scaffold and show that the resulting peptidomimetics maintain the desired pharmacological profile. Further, the 4R diastereomer of 1 was fully efficacious and approximately equipotent to morphine in the mouse warm water tail withdrawal assay following intraperitoneal administration and thus a promising lead for the development of opioid analgesics with reduced tolerance.
- Mosberg, Henry I.,Yeomans, Larisa,Harland, Aubrie A.,Bender, Aaron M.,Sobczyk-Kojiro, Katarzyna,Anand, Jessica P.,Clark, Mary J.,Jutkiewicz, Emily M.,Traynor, John R.
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p. 2139 - 2149
(2013/05/08)
-
- A new class of "electro-acid/base"-induced reversible methyl ketone colour switches
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Methyl ketone has been designed as a switching unit for electrically addressable molecular colour switches. A newly proposed mechanism of "electro-acid/base" (radical ions)-induced intermolecular proton transfer for the colour switch is proven clearly by cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and in situ UV-Vis spectroscopy. A dramatic spectral absorption shift (about 291 nm) is observed during the switching, and blue, yellow and green colours are obtained by adjusting the substituents on the methyl ketone-bridged unit. The in situ "electro-acid/base" is far more convenient than the conventional chemical stimulus of acids or bases for the manipulation of the molecular switching properties. This new switching method and molecular structure manipulation will inspire and accelerate the further development of broad switching materials and applications in ultrathin flexible displays, etc.
- Zhang, Yu-Mo,Li, Minjie,Li, Wen,Huang, Zhiyuan,Zhu, Shaoyin,Yang, Bing,Wang, Xiao-Chun,Zhang, Sean Xiao-An
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p. 5309 - 5314
(2013/09/23)
-
- Palladium-catalyzed reaction of arylboronic acids with aliphatic nitriles: Synthesis of alkyl aryl ketones and 2-arylbenzofurans
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An efficient palladium-catalyzed addition of arylboronic acids to aliphatic nitriles has been developed, providing a wide range of alkyl aryl ketones in moderate to excellent yields. It is noteworthy that sequential addition and intramolecular annulation reaction of 2-(2-hydroxyphenyl)acetonitriles with arylboronic acids are also conducted smoothly to afford 2-arylbenzofurans in good yields under the standard conditions. Georg Thieme Verlag Stuttgart. New York.
- Wang, Xingyong,Wang, Xiaodong,Liu, Miaochang,Ding, Jinchang,Chen, Jiuxi,Wu, Huayue
-
p. 2241 - 2244
(2013/09/02)
-
- Visible-light-mediated α-arylation of enol acetates using aryl diazonium salts
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Visible light mediates efficiently the α-arylation of enol acetates by aryl diazonium salts under mild conditions using [Ru(bpy)3]Cl 2 as a photoredox catalyst. The broad scope of the reaction toward various diazonium salts and enol acetates was explored. The application of this reaction in the concise synthesis of 2-substituted indoles was demonstrated
- Hering, Thea,Hari, Durga Prasad,Koenig, Burkhard
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p. 10347 - 10352
(2013/01/15)
-
- Discovery of amide replacements that improve activity and metabolic stability of a bis-amide smoothened antagonist hit
-
A bis-amide antagonist of Smoothened, a seven-transmembrane receptor in the Hedgehog signaling pathway, was discovered via high throughput screening. In vitro and in vivo experiments demonstrated that the bis-amide was susceptible to N-acyl transferase mediated amide scission. Several bioisosteric replacements of the labile amide that maintained in vitro potency were identified and shown to be metabolically stable in vitro and in vivo.
- Brown, Matthew L.,Aaron, Wade,Austin, Richard J.,Chong, Angela,Huang, Tom,Jiang, Ben,Kaizerman, Jacob A.,Lee, Gary,Lucas, Brian S.,McMinn, Dustin L.,Orf, Jessica,Rong, Minqing,Toteva, Maria M.,Xu, Guifen,Ye, Qiuping,Zhong, Wendy,Degraffenreid, Michael R.,Wickramasinghe, Dineli,Powers, Jay P.,Hungate, Randall,Johnson, Michael G.
-
scheme or table
p. 5206 - 5209
(2011/10/09)
-
- Synthesis, antileukemic and antiplatelet activities of 2,3-diaryl-6,7-dihydro-5H-1,4-diazepines
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The synthesis, antileukemic and antiplatelet activity evaluation of 2,3-diaryl-6,7-dihydro-5H-1,4-diazepines are described. In general, it was found that compound 17o showed moderate antileukemic activity against MOLT3 human leukemic cancer cell lines. An arachidonic acid induced platelet aggregation effect on washed rat platelets was studied. Compound 17i was found to be the most potent. The antiplatelet properties may be mediated by interference with the arachidonic acid pathway.
- Ramajayam,Giridhar, Rajani,Yadav,Balaraman,Djaballah, Hakim,Shum, David,Radu, Constantin
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p. 2004 - 2010
(2008/12/22)
-
- An efficient and time saving microwave-assisted selenium dioxide oxidation of 1,2-diarylethanones
-
Selenium dioxide oxidation of 1,2-diarylethanones to corresponding diones by conventional method takes upto 8 hr. The same oxidation under microwave radiations using dimethylsulfoxide as solvent reduces the reaction time considerably (30 to 90 sec). The method reported is efficient and time saving.
- Shirude,Patel,Giridhar,Yadav
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p. 1080 - 1085
(2007/10/03)
-
- Synthesis of novel substituted diaryl-1,4-diazepines
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In this paper a convenient route to new 2,3-diaryl-substituted 1,4-diazepines is described through cyclization of ethanedione derivatives and 1,3-propanediamine. The ethanedione derivatives required were synthesized by microwave-assisted oxidation from ethanones.
- Ramajayam,Giridhar, Rajani,Yadav
-
p. 901 - 906
(2008/02/12)
-
- Synthesis of 4- and 6-substituted nitroindoles
-
Enolizable ketones react with m-nitroaniline in the presence of strong base such as t-BuOK to give 4- and 6-substituted nitroindoles. The reaction proceeds via oxidative nucleophilic substitution of hydrogen in m-nitroaniline with enolate anions in positions ortho to the amino group giving anionic σH adducts that are additionally stabilized by intramolecular interaction between the amino and the carbonyl group. Spontaneous oxidation of the σH adducts followed by the Bayer type condensation of the produced ortho-aminonitrobenzyl ketones gives 4- and 6-substituted nitroindoles. The scope of this reaction and its basic mechanistic features are discussed.
- Moskalev, Nikolai,Barbasiewicz, Micha?,Ma?kosza, Mieczys?aw
-
p. 347 - 358
(2007/10/03)
-
- Electrochemical synthesis of nitroaromatic ketones
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Nitroaromatic ketones are readily prepared by nucleophilic aromatic substitution of hydrogen in nitroarenes by electrochemical oxidation. Carbanions of various ketones were added to selected nitroarenes in DMF/ketone mixtures leading to formation of the o
- Gallardo, Iluminada,Guirado, Gonzalo,Marquet, Jordi
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p. 261 - 267
(2007/10/03)
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- Nitric acid in dichloromethane solution. Facile preparation from potassium nitrate and sulfuric acid
-
Pure dry HNO3 can be liberated from KNO3 with 96% H2SO4 directly into CH2Cl2 to yield solutions of variable concentration for use in a number of organic reactions. The present method efficiently replaces the employment of 100% HNO3 in some synthetic applications, avoiding the problems associated in storage and handling the acid.
- Strazzolini, Paolo,Giumanini, Angelo G.,Runcio, Antonio
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p. 1387 - 1389
(2007/10/03)
-
- Experiments on the Chaperon effect in the nitration of aromatics
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A nitro group may be effectively delivered to the ortho position of alkylbenzenes, provided that a suitable chaperon function is located in α- position and a dilute of HNO3 in CH2Cl2 is used. The carbonyl function of an aldehyde or ketone is the best choice, but a carboxyl, alkoxycarbonyl, and amide groups all work well. The ether function showed a less pronounced ortho orientation effect, whereas the hydroxyl group was too prone to oxidation. Side reactions were minimal under the conditions employed. A para chaperon effect was seemingly at work in the CH2Cl2 nitration of benzenepropanenitrile. All the results were compared with the corresponding classical nitration in H2SO4.
- Strazzolini, Paolo,Giumanini, Angelo G.,Runcio, Antonio,Scuccato, Massimo
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p. 952 - 958
(2007/10/03)
-
- Substituted (1,2-Diarylethyl)amide Acyl-CoA:Cholesterol Acyltransferase Inhibitors: Effect of Polar Groups on in Vitro and in Vivo Activity
-
Substituted (1,2-diarylethyl)amides have been prepared and evaluated for their ability to inhibit microsomal acyl-CoA:cholesterol acyltransferase activity in vitro and to lower hepatic cholesteryl ester content in vivo in a cholesterol-fed hamster.Simple unsubstituted (diarylethyl)amides were potent inhibitors in vitro but showed poor activity in vivo.Introduction of polar groups at specific locations on the diarylethylamine moiety decreased in vitro activity but increased in vivo activity.Both effects were highly structure dependent, suggesting specific interactions which were mediating activity in each model.Optimization of these opposing effects led to compounds which were potent in both models.
- Clader, John W.,Berger, Joel G.,Burrier, Robert E.,Davis, Harry R.,Domalski, Martin,et al.
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p. 1600 - 1607
(2007/10/02)
-
- Inhibitors of acyl-coenzyme A: cholesterol acyl transferase
-
Amides of the formula STR1 wherein R1 and R2 are independently heteroaryl, X-substituted heteroaryl, X-substituted phenyl, N-substituted triazinyl or N-substituted imidazolyl; and in addition, one of R1 and R2 can be as defined above and the other can be phenyl; R3 is an alkyl chain of 2 to 25 carbon atoms, saturated or unsaturated; an alkyl chain as defined substituted by one or more substituents selected from the group consisting of phenyl, X-substituted phenyl, heteroaryl and X-substituted heteroaryl; an alkyl chain as defined interrupted by one or more groups independently selected from the group consisting of --O--, --S--, --SO--, --SO2 --, --NH--, --N(lower alkyl)--, --C(O)--, phenylene, X-substituted phenylene, heteroarylene and X-substituted heteroarylene; or an interrupted alkyl chain as defined substituted by one or more substituents selected from the group consisting of phenyl, X-substituted phenyl, heteroaryl and X-substituted heteroaryl; R4 is hydrogen, lower alkyl, phenyl, X-substituted phenyl, heteroaryl or X-substituted heteroaryl; or a pharmaceutically acceptable salt thereof, useful as inhibitors of acyl-coenzyme A:cholesterol acyl transferase and therefore in the treatment of atherosclerosis are disclosed.
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-
-
- Design of Integrated Fluorescent Estrogens: The Second Donor Effect on Absorption, Fluorescence, and Ground-State Molecular Orbital Properties of trans-4,4'-Methoxynitrostilbene Systems
-
In the design of inherently fluorescent ligands for the estrogen receptor, biological constraints limit to hydroxyl the functional groups that can be utilized as electron donors.In an attempt to optimize the fluorescent properties of such probes, we have studied the effect that a second alkoxy donor has on the fluorescence properties of two systems, peripherally located in a nitro-substituted diarylindene, and centrally located in a nitrostilbene.The second donor causes bathochromic shift in the absorbance spectrum (stilbene greater than diarylindene); however, the Stokes shift and fluorescence solvatochromism are less in the dual donor systems compared to the corresponding monodonor system.The fluorescence solvatochromism is investigated by using a model for solvent dispersive and dipole interactions.The relevant parameters are evaluated as follows: molecular geometry is obtained from X-ray crystallography, molecular mechanics, or semiempirical MO methods; molecular volumes are determined by molecular graphics; ground-state dipole moments calculated by the AM1 method; the noncollinearity of the ground- and excited-state dipoles is considered.This analysis rationalizes the effect of the second donor on reducing the fluorescence solvatochromism and demonstrates that the magnitude of this reduction depends on the conjugative contact of the second donor, being greater in the stilbene system than the diarylindene.Such an approach may be useful in the design of other fluorescent spectroscopic probes.
- Anstead, Gregory M.,Katzenellenbogen, John A.
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p. 1328 - 1334
(2007/10/02)
-
- Sructure an Mechanism in the Photo-Retro-Aldol Type Reactions of Nitrobenzyl Derivatives. Photochemical Heterolytic Cleavage of C-C Bonds
-
The photo-retro-aldol type reactions of several nitroaromatic compounds have been studied in aqueous solution over the pH 1-14 range.These reactions are observed only in aqueous or in predominantly aqueous solution.Catalysis of reaction due to hydroxide ion is observed for several derivatives.Quantum yields of reaction and product ratios (of nitrotoluene vs dinitrobibenzyl) are reported as a function of pH.The proposed mechanism of reaction involves heterolytic cleavage of the benzylic C-C bond from the triplet excited state in the primary photochemical step to generate a nitrobenzyl carbanion and a carbocation-equivalent fragment, except for the nitrophenylacetates 24-26, which eliminate CO2 in place of such a fragment.Photogenerated nitrobenzyl carbanions are efficiently trapped by molecular oxygen to give isolable hydroperoxides at pH 9 M-1 s-1.The results show that photochemical C-C bond heterolysis requires favorable stabilization of both the carbanion and carbocation-derived fragments.Hydroxide ion catalysis may also facilitate the process.The use of the nitrobenzyl moiety as the carbanion-stabilizing group appears to be generally applicable, as demonstrated by the systems studied.
- Wan, Peter,Muralidharan, S.
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p. 4336 - 4345
(2007/10/02)
-
- Enamines: Part V - Synthesis of Substituted Phenyl Benzyl Ketones and 2-Arylisatogens
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Three different approaches of o/p-nitrophenyl benzyl ketones and their limitation in the synthesis of 2-arylisatogens are described.
- Kulkarni, Sheshgiri N.,Kamath, H. V.,Bhamare, N. K.
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p. 667 - 669
(2007/10/02)
-
- A Facile One-Pot Synthesis of Vicinal Di- and Triketones from α-Methylene Ketones by NBS-DMSO Oxidation
-
The reaction of 1,2-diarylethanones (1a-u) with N-bromosuccinimide in anhydrous dimethyl sulphoxide afforded diarylethanediones (2a-u) in excellent yields.Under similar conditions, 1-phenyl-2-butanone (3) gave 1-phenyl-1,2-butanedione (4) in fair yield in addition to a small amount of 1-phenyl-3-methylthio-1,2-butanedione (5) and 1-phenyl-1-methylthio-2-butanone (6). 4-Phenyl-2-butanone (7), 1,3-diphenyl-2-propanone (9), and 1,3-diphenyl-1,3-propanedione (10) gave the corresponding triketones monohydrate (8) and (11). 1-Indanone (12), 2-indanone (13), and 1,3-indandione (14) gave ninhydrin (15) in good yields.In the case of 3-phenyl-1-indanone (16), 3-phenyl-2-bromo-1-indanone (17), 3-phenyl-2-bromo-1-indenone (18) and 3-phenyl-1-indenone (19) were obtained. 1-Phenyl-1-propanone (20) and 1-phenyl-1-butanone (22) gave the corresponding α-(methylthio)ketones (21) and (22). 1,3,3-Triphenylpropanone (24a) and 1-phenyl-3-methyl-1-butanone (24b) yielded only the corresponding α-bromoketones (25a,b) in good yields.These α-bromoketones, however, afforded the corresponding α-diketones (26a,b) in moderate yields when α-bromoketones reacted with dimethyl sulphoxide in the presence of AgBF4.
- Tatsugi, Jiro,Izawa, Yasuji
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p. 2747 - 2763
(2007/10/02)
-
- A NOVEL NUCLEOPHILIC SUBSTITUTION OF THE FORMYL GROUP IN p-NITROBENZALDEHYDE WITH SOME CARBANIONS
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p-Nitrobenzaldehyde reacts with some active methylene compounds in the presence of a strong base at low temperatures to give p-substituted nitrobenzenes by the two-step course involving the initial formation of the aldol adducts and the subsequent displacement of the carbinol moieties with excess carbanions.
- Iwasaki, Genji,Saeki, Seitaro,Hamana, Masatomo
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p. 173 - 176
(2007/10/02)
-
- STRUCTURES IN SOLUTION OF ADDUCTS OF 2,8-DIOXA-5-AZA-1-PHOSPHABICYCLOOCTANE AND SUBSTITUTED BENZILS
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Adducts of 2,8-dioxa-5-aza-1-phosphabicyclooctane and p,p'-dimethylbenzil, p-methoxy-p'-fluorobenzil, p-fluorobenzil, p,p'-difluorobenzil, p-nitrobenzil and p,p'-dinitrobenzil have been prepared.Although these materials could not be isolated in pure form because of rapid decomposition, the 31P and other NMR spectral data indicate that all of these materials are pentacoordinate in solution.The NMR data also indicate that all of these adducts undergo rapid intramolecular ligand reorganosation at room temperature.Variable temperature NMR measurements indicate that these rearrangements can be slowed and that they all have virtually the same activation energies, ΔG(excit.) 11.4-11.9 kcal/mole.The barrier to ligand reorganization is associated with the 5-membered dioxa containing ring adopting a diequatorial disposition.These results are discussed and compared to other systems.
- Denney, Donald B.,Denney, Dorothy Z.,Pastor, Stephen D.
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p. 191 - 198
(2007/10/02)
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- KETONE SYNTHESIS VIA PALLADIUM-CATALYZED CARBONYLATION OF ORGANOALUMINIUM COMPOUNDS
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Arylaluminium compounds react with aryl iodides and carbon monoxide in the presence of palladium complex to produce unsymmetrical ketones.
- Bumagin, N. A.,Ponomaryov, A. B.,Beletskaya, I. P.
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p. 4819 - 4822
(2007/10/02)
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- phosphonium Salts, 3. Reductive C-Acylation of Aromatic Aldehydes
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The phosphonium salts 5 are synthesized from aldehydes 1, arenecarbonyl chlorides 2 and triphenylphosphane (4), and can then be deprotonated to 7. 7 react as acyl anion equivalents with aromatic aldehydes 9 forming enol esters 10, which are transformed to alkanones 11.The new aldehyde 9->alkanone 11-transformation is characterised as a reductive C-acylation of aromatic aldehydes.
- Anders, Ernst,Gassner, Thomas
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p. 1034 - 1038
(2007/10/02)
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