- Thiyl radical promoted chemo- and regioselective oxidation of CC bonds using molecular oxygen: Via iron catalysis
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The first example of the thiyl radical promoted ligand-free iron-catalyzed oxidative cleavage of alkenes using molecular oxygen (1 atm) has been developed. The reaction proceeds under mild reaction conditions with high efficiency and high chemo- and regioselectivity. It features a broad substrate scope and excellent functional group compatibility, enabling facile access to valuable molecules for application in medicinal chemistry. Preliminary mechanistic studies reveal that a vital intermediate dioxetane might be involved in the reaction and a thiyl radical plays a synergistic role in facilitating the selective oxidation of the CC bond.
- Xiong, Baojian,Zeng, Xiaoqin,Geng, Shasha,Chen, Shuo,He, Yun,Feng, Zhang
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supporting information
p. 4521 - 4527
(2018/10/17)
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- Synthesis and palladium(II) metal chemistry of thiazoline/imidazoline derived ligands: An efficient catalyst for cross-coupling reactions of arylboronic acids with acid chlorides and aryl halides
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The synthesis, reactivity, spectroscopic characterization and catalytic activities of a series of Pd(II) complexes bearing the chelating ligands 2-(4,5-dihydrothiazol-2-yl)aniline (2) and 2-(4,5-dihydro-1H-imidazol-2-yl)aniline (3) are reported. The reactions of 2 with [Pd(COD)Cl2] in 1:1 and 1:2 (ligand into metal and metal into ligand) molar ratios afforded the mononuclear complexes, PdCl2{κ2?N,S ? 2?(4,5-dihydrothiazol-2-yl)aniline} (4), Pd{κ2?N,N’?2?(4,5-dihydrothiazol-2-yl)aniline}2 (5) and Pd{κ12?N,N’?κ22?N,S ? 2?(4,5-dihydrothiazol-2-yl)aniline}2 (6), respectively, in good yields. The neutral mononuclear palladium complexes PdCl2{κ2?N,N’?(4,5-dihydro-1H-imidazol-2-yl)aniline} (7) and Pd{κ2?N,N’?2?(4,5-dihydro-1H-imidazol-2-yl)aniline}2 (8) were synthesized using [Pd(COD)Cl2] with appropriate molar ratios. The palladium complexes 4–8 were evaluated for their catalytic activities in base assisted cross coupling reactions between acid chlorides and aryl halide with boronic acids. The complex 4 was found to be an efficient catalyst for producing unsymmetrical ketones (TOF = 19.8 min?1) while complex 7 was effective for making biaryls (TOF = 19.8 min?1).
- Sudharsan, Murugesan,Suresh
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p. 598 - 608
(2018/09/18)
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- One-Pot Synthesis of Arylketones from Aromatic Acids via Palladium-Catalyzed Suzuki Coupling
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A palladium-catalyzed one-pot procedure for the synthesis of aryl ketones has been developed. Triazine esters when coupled with aryl boronic acids provided aryl ketones in moderate to excellent yields (up to 95%) in the presence of 1 mol % Pd(PPh3)2Cl2 for 30 min. (Chemical Equation Presented).
- Wu, Hongxiang,Xu, Baiping,Li, Yue,Hong, Fengying,Zhu, Dezhao,Jian, Junsheng,Pu, Xiaoer,Zeng, Zhuo
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p. 2987 - 2992
(2016/04/26)
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- Magnesium salt promoted tandem nucleophilic addition-Oppenauer oxidation of aldehydes with organozinc reagents
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A magnesium salt promoted synthesis of ketones via tandem nucleophilic addition-Oppenauer oxidation of aldehydes using organozinc chemistry was demonstrated. Magnesium salts concomitantly generated via magnesium metal mediated organohalide zincation exhibit high efficacy for nucleophilic addition of organozinc reagents to aromatic aldehydes and thereafter Oppenauer oxidation whereby ketones are formed in high to excellent yields.
- Fu, Ying,Zhao, Xing Ling,Hügel, Hulmet,Huang, Danfeng,Du, Zhengyin,Wang, Kehu,Hu, Yulai
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supporting information
p. 9720 - 9724
(2016/10/31)
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- An efficient and recyclable thermoregulated phosphine-palladium catalyst for the carbonylative Suzuki coupling of aryl halides with arylboronic acids in water
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An efficient protocol has been developed for the carbonylative Suzuki coupling of aryl halides using the thermoregulated phosphine-palladium as a reusable catalyst in pure water. This protocol was applied to a wide variety of hindered and functionalized aryl iodides and bromides with arylboronic acids, to afford the desired biaryl ketones in good to high yields. The palladium catalyst was easily recovered in the aqueous phase and reused up to eight cycles without a significant decrease in its activity.
- Hao, Yuanping,Jiang, Jingyang,Wang, Yanhua,Jin, Zilin
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p. 106 - 110
(2015/09/28)
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- Acyl hydrazides as acyl donors for the synthesis of diaryl and aryl alkyl ketones
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In this communication we describe a novel strategy for the formation of valuable diaryl and aryl alkyl ketones from acyl hydrazides. A wide variety of ketones are prepared and the mild reaction conditions allow for the use of a range of functionalities, especially in the synthesis of diaryl ketones.
- Akhbar, Ahmed R.,Chudasama, Vijay,Fitzmaurice, Richard J.,Powell, Lyn,Caddick, Stephen
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p. 743 - 746
(2014/01/06)
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- In situ generation of palladium nanoparticles: Ligand-free palladium catalyzed pivalic acid assisted carbonylative Suzuki reactions at ambient conditions
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Highly selective carbonylative Suzuki reactions of aryl iodides with arylboronic acids using an in situ generated nanopalladium system furnished products in high yields. The reactions were performed under ambient conditions and in the absence of an added ligand. The key to success is the addition of pivalic acid, which can effectively suppress undesired Suzuki coupling. The synthesis can be easily scaled up, and the catalytic system can be reused up to nine times. The nature of the active catalytic species are discussed.
- Zhou, Qing,Wei, Shaohua,Han, Wei
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p. 1454 - 1460
(2014/03/21)
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- Selective Mg insertion into substituted mono- and dichloro arenes in the presence of LiCl: A new preparation of boscalid
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The LiCl-mediated Mg insertion into polysubstituted aryl chlorides bearing up to three chloro substituents in ortho or meta position selectively leads to Grignard reagents which readily react with various electrophiles. As an application, we have developed a new formal synthesis of boscalid. Georg Thieme Verlag Stuttgart - New York.
- Dunst, Cora,Knochel, Paul
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experimental part
p. 2064 - 2068
(2011/10/09)
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- Atom-efficient cross-coupling reactions of triarylbismuths with acyl chlorides under Pd(0) catalysis
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The atom-efficient cross-coupling reaction of triarylbismuths with a variety of aliphatic, aromatic, and hetero-aromatic acyl chlorides was demonstrated to afford high yields of cross-coupled ketones under palladium catalysis. The corresponding cross-coupling reaction with diacid chlorides also furnished bis-coupled ketones in good yields.
- Rao, Maddali L.N.,Venkatesh, Varadhachari,Banerjee, Debasis
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p. 12917 - 12926
(2008/03/28)
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- Oligothiophene-linked bisnaphthopyrans: Sequential and temperature- dependent photochromism
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Photochromic bisnaphthopyrans linked with oligothiophenes were synthesized and their photochromic behavior studied. Sequential and temperature-dependent photochromism was observed in the oligothiophene linked bisnaphthopyrans. The kinetics of photo and thermal processes in bisnaphthopyrans in comparison with naphthopyrans were studied, Substituent and linking effects on the photochromic properties are discussed. We demonstrate that the cross-talk between the two photochromophores is dependent on the length of the oligothiophene linker. The presence of the bithiophene linker led to high colorability and high quantum yield of coloration.
- Zhao, Weili,Carreira, Erick M.
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p. 2671 - 2688
(2008/03/14)
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- Novel 1-[2-(diarylmethoxy)ethyl]-2-methyl-5-nitroimidazoles as HIV-1 non-nucleoside reverse transcriptase inhibitors. A structure-activity relationship investigation
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1-[2-(Diarylmethoxy)ethyl]-2-methyl-5-nitroimidazoles (DAMNIs) is a novel family of HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) active at submicromolar concentration. Replacement of one phenyl ring of 1-[2-(diphenylmethoxy)ethyl]-2-methyl-5-nitroimidazole (4) with heterocyclic rings, such as 2-thienyl or 3-pyridinyl, led to novel DAMNIs with increased activity. In HIV-1 WT cell-based assay the racemic 1-{2-[α-(thiophen-2-yl) phenylmethoxy]ethyl}-2-methyl-5-nitroimidazole (7) (EC50 = 0.03 μM) proved 5 times more active than compound 4. Docking experiments showed that the introduction of a chiral center would not affect the binding of both (R)-7 and (S)-7. The internal scoring function of the Autodock program calculated the same inhibition constant (Ki = 7.9 nM) for the two enantiomers. Compounds 7 (ID50 = 8.25 μM) were found more active than efavirenz (ID50 = 25 μM) against the viral RT carrying the K103N mutation, suggesting for these compounds a potential use in efavirenz based anti-AIDS regimens.
- De Martino, Gabriella,Regina, Giuseppe La,Pasquali, Alessandra Di,Ragno, Rino,Bergamini, Alberto,Ciaprini, Chiara,Sinistro, Anna,Maga, Giovanni,Crespan, Emmanuele,Artico, Marino,Silvestri, Romano
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p. 4378 - 4388
(2007/10/03)
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- Rh(1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) (COD) tetrafluoroborate, an unsymmetrical Rh-homoazallylcarbene: Synthesis, X-ray structure and reactivity in carbonyl arylation and hydrosilylation reactions
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The synthesis of novel Rh(1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6- tetrahydropyrimidin-2-ylidene)(COD) tetrafluoroborate (1, COD = η4-1,5-cyclooctadiene) is described. The N-heterocyclic carbene acts as a bidentate ligand with the carbene coordinating to the Rh(I) center and an arene group acting as a homoazallyl ligand. 1 was used in various carbonyl arylation and hydrosilylation reactions allowing the formation of the desired products with unprecedented selectivity and efficiency. Thus, turn-over numbers (TONs) up to 2000 were achieved.
- Imlinger, Nicolas,Wurst, Klaus,Buchmeiser, Michael R.
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p. 4433 - 4440
(2007/10/03)
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- Arylation of carbonyl compounds catalyzed by rhodium and iridium 1,3-R 2-tetrahydropyrimidin-2-ylidenes: Structure-reactivity correlations
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Six different well-defined rhodium and iridium N-heterocyclic carbene complexes, i.e., RhCl-(1,3-dimesityltetrahydropyrimidin-2-ylidene)(COD) (1), RhBr(1,3-dimesityltetrahydropyrimidin-2-ylidene)-(COD) (2), RhCl[1,3-di(2- propyl)tetrahydropyrimidin-2-ylidene](COD) (3), IrCl(1,3- dimesityltetrahydropyrimidin-2-ylidene)(COD) (4), Rh(CF3COO) (1,3-dimesityltetrahydropyrimidin-2-ylidene)(COD) (5), and IrBr[1,3-di(2-propyl) tetrahydropyrimidin-2-ylidene](COD) (6) (COD = 1,5-cyclooctadiene, mesityl = 2,4,6-trimethylphenyl) have been used as catalysts for the arylation of aldehydes and α,β-unsaturated ketones using different arylboronic acids. Compounds 1-4 and 6 were prepared by reaction of [RhCl(COD)]2 and [IrCl(COD)]2, respectively, with a base and the corresponding 1,3-R2-tetrahydropyrimidinium salt. Compound 5 was prepared by reaction of 1.0 equivalents of CF3COOAg with 1. The use of an excess of CF3COOAg resulted in the replacement of Rh(I) by Ag(I) and yielded Ag(1,3-dimesityltetrahydropyrimidin-2-ylidene)+Rh 2(CF3COO)3(COD)- (8). Compounds 4 and 8 were characterized by X-ray analysis. The activity of the rhodium complexes increased in the order 5 > 3 > 1 > 2, indicating the necessity of strongly electron-withdrawing groups at the metal centers, thus increasing their nucleophilicity. In due consequence, the softer iridium complexes 4 and 6 exhibited significantly reduced catalytic activity albeit with enhanced selectivity. The syntheses of the metal complexes as well as a detailed study on their reactivity in the arylation of carbonyl compounds using equimolar amounts of arylboronic acid and carbonyl compound in the presence of 0.08-1 mol % catalyst are presented.
- Imlinger, Nicolas,Mayr, Monika,Wang, Dongren,Wurst, Klaus,Buchmeiser, Michael R.
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p. 1836 - 1843
(2007/10/03)
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- Benzylation via Tandem Grignard Reaction - Iodotrimethylsilane (TMSI) Mediated Reduction
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A method has been developed which allows for the large scale preparation of biarylmethanes.This method involves the initial formation of biarylmethanols via reaction of aryl Grignards with carbonyl compounds followed by a subsequent reduction with iodotrimethylsilane (TMSI).A number of improvements over existing literature procedures are reported as well as previously unobserved dimerizations.Studies reveal that as few as 3 equiv of TMSI will give complete reduction in most cases where either of the substituents are not heteroaromatic.Mono-substituted alkanols react with TMSI to afford the corresponding iodides.A mechanistic study of the TMSI reduction is also reported.
- Stoner, Eric J.,Cothron, Darlene A.,Balmer, Mary K.,Roden, Brian A.
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p. 11043 - 11062
(2007/10/02)
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- 2-(Trifluoromethylsulfonyloxy)pyridine as a Reagent for the Ketone Synthesis from Carboxylic Acids and Aromatic Hydrocarbons
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A new reagent 2-(trifluoromethylsulfonyloxy)pyridine (TFOP) was prepared by the reaction of sodium salt of 2-pyridinol with trifluoromethylsulfonyl chloride in dioxane.The conpound TFOP in trifluoroacetic acid has been found to intermolecularly dehydrate from benzoic acid and aromatic hydrocarbons to give the corresponding benzophenones in high yield.It was further elucidated, in the reaction of fluorene, that a variety of carboxylic acids can be used as the acyl precursor for the aromatic ketone synthesis in conjunction with the TFOP/TFA system.This acylation procedure has been applied to the synthesis of 2-acylthiophenes, which are hard to prepare in a satisfactory yield by the classical Friedel-Crafts reaction using aluminum chloride as the catalyst.
- Keumi, Takashi,Yoshimura, Kiichiro,Shimada, Masakazu,Kitajima, Hidehiko
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p. 455 - 460
(2007/10/02)
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- Synthesis of α methyl 4 (2 thienylcarbonyl)benzeneacetic acid, suprofen, and derivatives
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A series of compounds with general structure Het CO Ar CH(CH3)COOH was prepared for pharmacological screening. Different synthetic approaches are described. α Methyl 4 (2 thienylcarbonyl)benzeneacetic acid (compound III-l, suprofen), was found to show a marked antiwrithing activity. Furthermore this compound proved to be a potent inhibitor of prostaglandin biosynthesis.
- van Daele,Boey,Sipido,De Bruyn,Janssen
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p. 1495 - 1501
(2007/10/05)
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