- Redox-Neutral ortho Functionalization of Aryl Boroxines via Palladium/Norbornene Cooperative Catalysis
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Palladium/norbornene (Pd/NBE) cooperative catalysis, also known as the Catellani reaction, has become an increasingly useful method for site-selective arene functionalization; however, certain constraints still exist because of its intrinsic mechanistic pathway. Herein, we report a redox-neutral ortho functionalization of aryl boroxines via Pd/NBE catalysis. An electrophile, such as carboxylic acid anhydrides or O-benzoyl hydroxylamines, is coupled at the boroxine ortho position, and a proton as the second electrophile is introduced at the ipso position. This reaction does not require extra oxidants or reductants and avoids stoichiometric bases or acids, thereby tolerating a wide range of functional groups. In particular, orthogonal chemoselectivity between aryl iodide and boroxine moieties is demonstrated, which could be used to control reaction sequences. Finally, a deuterium-labeling study supports the ipso protonation pathway. This unique mechanistic feature could inspire the development of a new class of Pd/NBE-catalyzed transformations.Poly-substituted aromatics are ubiquitously found in drugs and agrochemicals. To realize streamlined synthesis, it is highly attractive if functional groups can be site-selectively introduced at unactivated positions with common arene starting materials. Here, a method is developed to directly introduce acyl and amino groups at unactivated ortho positions of readily available aryl boron compounds. Compared with the known ortho functionalization approaches, this method does not require stoichiometric bases, external oxidants, or reductants. Consequently, the reaction is chemoselective: a wide range of functional groups, including highly reactive aryl iodides, can be tolerated. The primary innovation lies in the use of a proton to terminate the ipso aryl intermediate and regenerate the active palladium catalyst. This unique mode of reactivity in the palladium/norbornene catalysis should open the door for developing new redox-neutral methods for site-selective arene functionalization.A redox-neutral ortho functionalization of aryl boroxines via palladium/norbornene cooperative catalysis is developed. The ortho amination and acylation are achieved with carboxylic acid anhydrides and O-benzoyl hydroxylamines as an electrophile, respectively, whereas protonation occurs at the ipso position. This transformation avoids using either extra oxidants and reductants or stoichiometric bases and acids. In addition, orthogonal chemoselectivity between aryl iodide and boroxine moieties is demonstrated for pathway divergence.
- Li, Renhe,Liu, Feipeng,Dong, Guangbin
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supporting information
p. 929 - 939
(2019/04/10)
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- A synthesis of biaryl ketones via the C–S bond cleavage of thiol ester by a Cu/Ag salt
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We report the synthesis of biaryl ketones via an unprecedented copper/silver catalyzed acylative cross-coupling of thiol esters with either an arylboronic acid or a potassium aryltrifluoroborate. This new method proceeds without a requisite Pd-catalyst and Cu(I)TC mediator, and is efficient, versatile, operationally simple, and accommodating functionally diverse thiol esters, arylboronic acids, and potassium aryltrifluoroborates.
- Ghosh, Prasanjit,Ganguly, Bhaskar,Das, Sajal,Perl, Eliyahu
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p. 2751 - 2756
(2017/06/23)
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- The second aryl ketone compounds
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The invention provides a synthetic method for diaryl ketone compounds. The method comprises the following steps: adding ester derivatives of raw material diaryl methanol, DDQ and water into an organic solvent, carrying out stirring, then carrying out heating to 110 to 140 DEG C and carrying out reaction for 0.5 to 12 h, and subjecting obtained reaction liquid to after-treatment so as to obtain the diaryl ketone compounds, wherein the ester derivatives of the raw material diaryl methanol have a structural formula as shown in a formula (V), (VI), (VII) or (VIII), and one-to-one correspondingly obtained products have the structural formula as shown in the formula (I), (II), (III) or (IV). The synthetic method for the diaryl ketone compounds provided by the invention has the advantages of simple, convenient and safe operation, mild reaction conditions and high product selectivity.
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Paragraph 0051; 0052
(2017/08/24)
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- Diaryl a ketone compound catalytic oxidation synthesis method
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The invention provides a catalytic oxidation synthesis method of a diaryl ketone compound. In an organic solvent, ester derivatives of diaryl methanol are used as reaction substrates, DDQ and TBN are used as catalysts, oxygen is used as an oxidant, so as to react for 1 to 12 h under the conditions of oxygen pressure of 0.1 to 0.4 MPa and temperature of 110 to 140 DEG C, and post processing is performed on reaction liquid, so as to obtain a product of the diaryl ketone compound; structural formulas of the ester derivatives of the diaryl methanol as the reaction substrates are shown in the formulas (V), (VI), (VII) or (VIII), and structural formulas of products which are correspondingly obtained one by one are shown in the formulas (I), (II), (III) or (IV). The catalytic oxidation synthesis method has the advantages of simplicity, convenience and safety in operation, mild reaction condition, high product selectivity and environmental friendliness.
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Paragraph 0051-0052
(2020/05/05)
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- Iron-catalyzed carbonylation of aryl halides with arylborons using stoichiometric chloroform as the carbon monoxide source
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A general iron-catalyzed carbonylative Suzuki-Miyaura coupling of aryl halides with arylborons is reported, using stoichiometric CHCl3 as the CO source. The high efficiency, economy, selectivity, and operational simplicity of this transformation make this method a valuable tool in organic synthesis. Importantly, the presented strategy allows effective 13C labeling simply by using the commercially available 13C-labeled CHCl3. On the basis of the initial mechanistic exploration, an aryl radical intermediate is proposed in the present carbonylation process.
- Zhao, Hongyuan,Du, Hongyan,Yuan, Xiaorong,Wang, Tianjiao,Han, Wei
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supporting information
p. 5782 - 5787
(2016/11/06)
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- Visible light mediated efficient oxidative benzylic sp3 C-H to ketone derivatives obtained under mild conditions using O2
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A photooxygenation of benzylic sp3 C-H reaction has been demonstrated using O2 mediated by visible light. This protocol provides a simple and mild route to obtain ketones from benzylic sp3 C-H bonds. Various benzylic sp3 C-H bonds can be transformed into the desired ketone derivatives in moderate to good yields. The 18O2 labelling experiments demonstrated that the oxygen introduced into ketone originated from dioxygen. A plausible mechanism has been proposed accordingly.
- Yi, Hong,Bian, Changliang,Hu, Xia,Niu, Linbin,Lei, Aiwen
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supporting information
p. 14046 - 14049
(2015/09/15)
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- Transition-metal-free, ambient-pressure carbonylative cross-coupling reactions of aryl halides with potassium aryltrifluoroborates
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We disclose an unprecedented transition-metal-free carbonylative cross coupling of aryl halides with potassium aryl trifluoroborates even at atmospheric pressure of carbon monoxide. This protocol is efficient, operationally simple, and shows wide scope with regard to both aryl halides and potassium aryl trifluoroborates containing a series of active functional groups.
- Jin, Fengli,Han, Wei
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supporting information
p. 9133 - 9136
(2015/06/08)
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- Tetraethylammonium iodide catalyzed synthesis of diaryl ketones via the merger of cleavage of C-C double bonds and recombination of aromatic groups
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An efficient method for synthesizing diaryl ketones via merging of oxidative cleavage of C-C double bonds and recombination of aromatic groups is developed with Et4NI (2.5 mol%) as the catalyst and NaIO4 as the oxidant. The control experiments provide valuable mechanistic insights into the formation of diaryl ketones, and suggest that NaIO4 serves as an epoxidation and nucleophilic deformylation reagent.
- Zeng, Xianghua,Xu, Daqian,Miao, Chengxia,Xia, Chungu,Sun, Wei
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p. 46494 - 46497
(2014/12/10)
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- Facile preparation of aromatic ketones from aromatic bromides and arenes with aldehydes
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Aromatic ketones were efficiently prepared in good yields by the reactions of aryl bromides with n-BuLi, followed by the reactions with aromatic aldehydes or aliphatic aldehydes and the subsequent treatment with molecular iodine and K2CO3, in a one-pot method. The same treatment of arenes, instead of aromatic bromides, also provided the corresponding aromatic ketones in good yields. Using these methods, various diaryl ketones and alkyl aryl ketones bearing electron-rich aromatics and electron-deficient aromatics could be prepared efficiently by a simple, transition-metal-free, and therefore environmentally benign experimental procedure.
- Ushijima, Sousuke,Dohi, Souya,Moriyama, Katsuhiko,Togo, Hideo
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experimental part
p. 1436 - 1442
(2012/03/09)
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- Ionically tagged benzimidazole palladium(II) complex: Preparation and catalytic application in cross-coupling reactions
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An imidazolium chloride tagged palladium(II) complex has been conveniently prepared and structurally analyzed. It is active toward cross-coupling of arylboronic acid with aryl halide and benzoyl chloride, giving moderate to high yield of the desired biaryls and aryl ketones, respectively. The present phosphine-free (N-N)Pd(II) complex could be efficiently recycled at least four times with minor decrease of activity in the aqueous Suzuki-Miyaura coupling reaction.
- Zhang, Li,Wu, Junliang,Shi, Lijun,Xia, Chungu,Li, Fuwei
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supporting information; experimental part
p. 3897 - 3901
(2011/08/09)
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- Benzylated 1,2,3-triazoles as anticoccidiostats
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Substituted 5-amino-4-carbamoyl-1,2,3-triazoles 3a-w were prepared by two synthetic schemes and evaluated in vivo for anticoccidial activity. Both schemes proceeded by brominating appropriately substituted toluenes 4a-s,v to 5a-s,v. In Scheme I, the brominated benzyl analogues 5 were converted to the corresponding benzyl azides 6, which were treated with cyanoacetamide to yield 1-substituted-5-amino-4-carbamoyl-1,2,3-triazoles 3. In Scheme II, the benzyl halides 5 were employed to alkylate the sodium salt of 5-amino-4-carbamoyl-1,2,3-triazole (7). Preliminary screening data against Eimeria acervulina and E. tenella in chickens suggested structural requirements for maximizing activity. Further evaluation against a relatively resistant series of eight Eimeria field isolates revealed L-651,582 (3a) to be a highly effective coccidiostat. However, unacceptable tissue residues precluded further development. Mechanistic studies on this series of 5-amino-4-carbamoyl-1,2,3-triazoles and, in particular, on L-651,582 (3a) revealed that its mode of action does not involve inhibition of IMP dehydrogenase, but probably interferes with host cell calcium entry. In addition, L-651,582 has been found to have antiproliferative activity in several disease models and was recently reported to possess antimetastatic activity in a model of ovarian cancer progression.
- Bochis,Chabala,Harris,Peterson,Barash,Beattie,Brown,Graham,Waksmunski,Tischler,Joshua,Smith,Colwell,Wyvratt Jr.,Fisher,Tamas,Nicolich,Schleim,Wilks
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p. 2843 - 2852
(2007/10/02)
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- 5-amino or substituted amino 1,2,3-triazoles
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Novel 5-amino or substituted amino 1,2,3-triazoles are disclosed as having anticoccidial activity. The compounds are useful for controlling coccidiosis when administered in minor quantities to animals, in particular to poultry, usually in admixture with a
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- Carboxylic Trifluoromethanesulfonic Anhydrides as Highly Effective Acylation Agents. - Perfluoroalkanesulfonic Acid Catalyzed Acylation of Arenes
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Arene- and alkanecarboxylic trifluoromethanesulfonic anhydrides 2 and 5 are highly effective acylation agents, which react without Friedel-Crafts catalysts even with deactivated aromatics to yield aryl ketones 3 and 6, respectively.Acylation of arenes with carbonyl chlorides 4 and catalytic amounts of perfluoroalkanesulfonic acid gives ketones 3 and 6, resp., in good yields.Under similar conditions other strong Broensted acids show a considerably smaller degree of catalytic effect.
- Effenberger, Franz,Sohn, Erich,Epple, Gerhard
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p. 1195 - 1208
(2007/10/02)
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