- Luminescent tungsten(vi) complexes as photocatalysts for light-driven C-C and C-B bond formation reactions
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The realization of photocatalysis for practical synthetic application hinges on the development of inexpensive photocatalysts which can be prepared on a large scale. Herein an air-stable, visible-light-absorbing photoluminescent tungsten(vi) complex which can be conveniently prepared at the gram-scale is described. This complex could catalyse photochemical organic transformation reactions including borylation of aryl halides, such as aryl chloride, reductive coupling of benzyl bromides for C-C bond formation, reductive coupling of phenacyl bromides, and decarboxylative coupling of redox-active esters of alkyl carboxylic acid with high product yields and broad functional group tolerance.
- Chan, Kaai-Tung,Che, Chi-Ming,Du, Lili,Liu, Yungen,Phillips, David Lee,To, Wai-Pong,Tong, Glenna So Ming,Wu, Liang-Liang,Yu, Daohong
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p. 6370 - 6382
(2020/07/15)
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- Photo-catalytic preparation method of bibenzyl compounds
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The invention relates to a preparation method of bibenzyl compounds. A compound represented by a formula (A) and a compound represented by a formula (C) carry out reactions under the action of an organic tungsten catalyst and an alkali in the presence of light to generate bibenzyl compounds represented by the formula (B). The method is simple and is easy to operate. The yield is high, and the application range is wide. Moreover, the invention also provides an application of a tungsten complex in organic chemical reactions as a photocatalyst.
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Paragraph 0049-0053; 0055
(2020/02/27)
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- Application of novel coupling reaction to preparing carbon-carbon bond structured compounds
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The invention relates to application of a novel coupling reaction to preparing carbon-carbon bond structured compounds and mainly provides a reaction between alkyl indium compounds and halides. The reaction between the alkyl indium compounds and the halides can produce corresponding carbon-carbon structured products. The novel coupling reaction is high in process yield, broad in functional group tolerance and good in compatibility.
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Paragraph 0099-0103
(2019/06/30)
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- Preparation of Alkyl Indium Reagents by Iodine-Catalyzed Direct Indium Insertion and Their Applications in Cross-Coupling Reactions
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An efficient method for the synthesis of alkyl indium reagent by means of an iodine-catalyzed direct indium insertion into alkyl iodide in THF is reported. The thus-generated alkyl indium reagents effectively underwent Pd-catalyzed cross-coupling reactions with various aryl halides, exhibiting good compatibility to a variety of sensitive functional groups. By replacing THF with DMA and using 0.75 equiv of iodine, less reactive alkyl bromide could be used as substrate for indium insertion with equal ease.
- Zhi, Man-Ling,Chen, Bing-Zhi,Deng, Wei,Chu, Xue-Qiang,Loh, Teck-Peng,Shen, Zhi-Liang
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p. 3017 - 3023
(2019/02/26)
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- Divinyl aromatic compounds and Di(methacrylates) prepared by acid-catalyzed transformations of bis[4-(1-hydroxyethyl)phenyl]alkanes
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The mechanism of formation of divinyl aromatic monomers including p,p′-divinyldiphenylmethane and 1,2-p,p′-divinyldiphenylethane and of their dimerization via terminal vinyl groups was studied. The factors affecting the structure, composition, and propert
- Zaitsev,Shvabskaya
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experimental part
p. 1783 - 1794
(2012/02/15)
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- Synthesis of potential fungicidal bibenzyls from bio-renewable source
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Acetylation of bibenzyl 1 yields 4,4′-diacetylbibenzyl 2, which on condensation with different aryl amines gives corresponding Schiffs bases in situ. Nucleophilic addition of 2-mercaptopropionic acid or 2-mercaptosuccinic acid on Schiff's bases followed b
- Siddiqui, Ibadur R.,Singh, Jaya,Singh, Pravin K.,Singh, Jagdamba
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p. 1460 - 1464
(2007/10/03)
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- Facile synthesis and fungicidal activity of novel 4,4′ -bis[2″ -(5?-substituted rhodanin-3?-yl)thiazol-4″-yl]bibenzyls
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Acylation of bibenzyl, followed by reaction with thiourea and I2 in the presence of NH3, yields 4,4′-bis(2″-aminothiazol- 4″-yl)bibenzyl 3. Compound 3, on treatment with CS2 in the presence of NH3 and cyclizatio
- Siddiqui,Singh, Pravin K.,Singh, Jaya,Singh, Jagdamba
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p. 2102 - 2106
(2007/10/03)
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- Efficient photodecarboxylation of 3- and 4-acetylphenylacetic acids in aqueous solution
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The photochemistry of 3- and 4-acetylphenylacetic acids (6 and 7) has been studied in aqueous solution. This work is a continuation of research efforts aimed at understanding the structural effects on the efficacy for benzyl carbanion photogeneration via photodecarboxylation. The nitro group (at the 3- and 4-positions) is known to be an exceptionally good activating group on the benzene ring - because of its enhanced electron-withdrawing effect in the excited triplet state - for photodecarboxylation and the related photo-retro-aldol type process. It is shown in this work that the acetyl group is an equally good activating group for the photodecarboxylation. Thus, the photochemistry of 6 and 7 parallels much of what was observed for the corresponding nitrophenylacetic acids 1 and 2. Both 6 and 7 photodecarboxylate efficiently (Φd = 0.60 and 0.22, respectively, at pH 7) via the carboxylate form, to give observable (by laser flash photolysis) benzyl carbanion or related intermediates. The meta isomer 6 displays an acid-catalyzed pathway for photodecarboxylation at pH 3 and along with its enhanced overall reactivity, is consistent with a meta effect of the acetyl group. Triplet state reactivity is inferred from sensitization and laser flash photolysis experiments. Based on the results of this work, the acetyl group may now be viewed as an "enhanced" electron-withdrawing group (in the excited state) when attached to a benzene ring (i.e., in acetophenone derivatives) that is capable of inducing ionic reactions, which is not the traditional photochemistry that is expected from such compounds.
- Huck, Lawrence A.,Xu, Musheng,Forest, Kaya,Wan, Peter
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p. 1760 - 1768
(2007/10/03)
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- Efficient photodecarboxylation of aroyl-substituted phenylacetic acids in aqueous solution: A general photochemical reaction
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Photolysis (254-350 nm) of a variety of aroyl-substituted phenylacetic acids and p-acetylphenylacetic acid in aqueous solution at pH > pK(a) resulted in efficient photodecarboxylation (Φ = 0.2-0.7), to give in most cases a single product arising via the corresponding arylmethyl carbanion, indicating that photodecarboxylation is an efficient and general reaction for these types of compounds.
- Xu,Wan
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p. 2147 - 2148
(2007/10/03)
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- Photo-Arbuzov rearrangements of dimethyl benzyl and dimethyl p-acetylbenzyl phosphite
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The direct ultraviolet irradiation of dimethyl benzyl phosphite (1) and dimethyl p-acetylbenzyl phosphite (8) was investigated in acetonitrile, cyclohexane, and benzene. Phosphite 1 gives predominantly the photo-Arbuzov product, dimethyl benzylphosphonate (2), in 67-81% accountability yields, based of phosphite consumed, along with minor amounts of bibenzyl (20) and dimethyl phosphite (10). The quantum yield for formation of 2 in cyclohexane, φp, is 0.43. By contrast, irradiation of phosphite 8 yields only 7-13% of photo-Arbuzov phosphonate (9) but relatively large amounts of radical diffusion products: dimethyl phosphite (10) the p-acetylbenzyl radical dimer (11); and p-acetyltoluene (12). Evidently 8, closely related to acetophenone, reacts predominantly via the triplet excited estate to generate long-lived, triplet, free-radical pairs (6 and 7a). In benzene, further products (15, 16, 17a and 17b) are identified that result from addition of the phosphinoyl radical (6) to benzene to give cyclohexadienyl radical 14, followed by combination and disproportionation reactions with radical 7a. (Total product quantum yields in benzene (Σφi) = 0.47.) In benzene, accountabilities of radical 6 from photolysis of 8 as high as 56% are encountered along with up to 92% accountabilities of p-acetylbenzyl (7a) radicals. Addition of radical scavengers PhSH, PhCH2Br, and TEMPO in the three solvents establishes the cage yield of 9 as 3-5%. The products of radical trapping provide further proof of the radical-pair nature of the photolysis of phosphite 8, including a 95% accountability of 6 with PhCH2Br in benzene. It is proposed that the CH2-O scission of triplet 8 must occur concertedly with partial phosphoryl (P=O) bond formation. The trapping of radicals 6 and 7b from irradiation of phosphite 1 as the benzene adducts 22 and 23, analogous structurally to those (16 and 17) from phosphite 8, supports the postulation that photoisomerization of 1 to 2 proceeds via short-lived, presumably singlet, free-radical pairs.
- Ganapathy, Srinivasan,Sekhar, B. B. V. Soma,Cairns, S. Matthew,Akutagawa,Bentrude, Wesley G.
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p. 2085 - 2096
(2007/10/03)
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- Radical-pair intermediates in the photolysis of arylmethoxy groups attached to three-coordinate phosphorus
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Stereochemical and product studies of the photochemistry of the title compounds is interpreted in terms of concerted as well as singlet and triplet radical-pair mechanisms.
- Bentrude, Wesley G.,Bhanthumnavin, Worawan,Ganapathy, Srinivasan
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p. 537 - 540
(2007/10/03)
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- Liquid Crystalline Asymmetric Bisphenyl-4,4'-bibenzyldicarboxylates and Polysiloxanes with Bisphenyl-4,4'-bibenzyldicarboxylat Components in the Side Chains, Synthesis and Characterization
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Asymmetric bisphenyl bibenzyl-4,4'-dicarboxylates with an alkenyloxy- or the 10-undecenoylgroup in the p-position of one terminal benzene ring and the butyl-, an alkoxy- or the thiomethylgroup in the p-position of the other terminal benzene ring (12-14) are synthesized.The olefins 12-14 are added to a poly(methylhydrogensiloxane) 15 to give mesomorphic side chain polysiloxanes 16-18.Data of liquid crystalline properties of 12-14, 16-18 and precursors are discussed.
- Boberg, Friedrich,Mueller, Enno,Reddig, Wolfram
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p. 136 - 142
(2007/10/02)
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- Synthesis and Properties of Diethyl 5,10-Dihetera-5,10-dihydroindenoindene-2,7-dicarboxylates
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A series of six heterocyclic diesters 1b-6b containing all combinations of nitrogen, sulfur, and selenium has been prepared from a common precursor, diethyl 2,2'-dinitrostilbene-4,4'-dicarboxylate.Electrochemical analysis showed oxidation potential increases in the order NA liquid crystals.A new synthetic method leading to the indoloindazole ring system has been found.
- Kaszynski, Piotr,Dougherty, Dennis A.
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p. 5209 - 5220
(2007/10/02)
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- Electrophilic Substitution in (Arene)tricarbonylchromium Complexes. Part 1.
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The Friedel-Crafts acetylation of several (arene)tricarbonylchromium complexes have been investigated.From the results it is concluded that the tricarbonylchromium group deactivates to a small extent towards electrophilic substitution the ring to which it is attached.In the case of tricarbonyl(diphenylmethane)chromium (1; n=1), however, attack occurred on both rings to about an equal extent, possible explanations for this unexpected behaviour are advanced.
- von Rosenberg, Joseph L.,Pinder, A. Reginald
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p. 747 - 752
(2007/10/02)
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- Photochemical Transformations. 26. Sensitized and Unsensitized Photoreactions of Some Benzyl Chlorides in tert-Butyl Alcohol
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Benzyl chloride and a variety of meta- and para-substituted derivatives have been irradiated in tert-butylalcohol at 254 nm or in acetone-tert-butyl alcohol mixtures at 300 nm.Quantum and chemical yields of photosolvolysis products (benzyl tert-butyl ether and/or benzyl alcohol), photohomolysis products (bibenzyl and 4-phenyl-2-methyl-2-butanol), and corresponding products from substituted benzylchlorides have been measured as functions of substrate concentration and medium composition.Sensitized reactions favor bond heterolysis, but direct irradiations favor homolysis, although reactions are not clean in either case.There is no correlation between quantum yields for photosolvolysis and Hammett ? or Brown ?+ constants, and no salt effects of added lithium perchlorate were observed, in either direct or sensitized reactions.
- Cristol, Stanley J.,Bindel, Thomas H.
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p. 951 - 957
(2007/10/02)
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