- SYNTHESIS AND SOME PHYSICAL PROPERTIES OF TRANS-4- left brace beta -(TRANS-4 prime -N-ALKYLCYCLOHEXYL)-1 prime right brace -ETHYLCYCLOHEXANE-1-CARBOXYLATES.
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A series of trans-4- left brace beta -(trans-4 prime -n-alkylcyclohexyl)-1 prime right brace -ethylcyclohexane-1-carboxylates, which show nematic phases, was prepared. Their transition temperatures and enthalpies were measured. Their bulk viscosities and birefringences were determined by extrapolation. The influence of terminal halogeno and alkyl groups on the N-I transition temperatures and the C-N transition enthalpies for the trans-4- left brace beta -(trans4- prime -n-alkylcyclohexyl)-1 prime right brace -enthylcyclohexane-1-carboxylates is discussed and compared with the influence for the 1-(trans-4- prime -n-alkylcyclohexyl)-2-(4 double prime -helobiphenyl-4- prime -yl)ethanes. The bulk viscosity as a function of the third power of the van der Waals radius of the helogeno group and the birefringence as a function of the van der Waals radius of the halogeno group for the 4-halophenyl trans-4 prime - left brace beta -(trans-4- double prime -n-propylcyclohexyl)-1 double prime right brace -ethylcyclohexane-1 prime -carboxylates are discussed.
- Takatsu,Takeuchi,Sato
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Read Online
- Synthesis of Fluorenes and Dibenzo[ g,p]chrysenes through an Oxidative Cascade
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We have developed robust, operationally simple syntheses of fluorenes and of dibenzo[g,p]chrysenes through oxidative cascade processes. These structures that are commonly encountered in optoelectronic materials, dyes, and pharmaceutical products are acces
- Dickinson, Cody F.,Tius, Marcus A.,Yap, Glenn P. A.
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supporting information
p. 1559 - 1563
(2022/02/07)
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- Pd-catalyzed protecting-group-free cross-couplings of iodophenols with atom-economic triarylbismuth reagents
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An efficient protocol for the protecting-group-free synthesis of unsymmetrical hydroxybiaryls via the Pd-catalyzed cross-couplings of unprotected iodophenols with triarylbismuth reagents is described. The presented protocols exhibits good to high yields of hydroxybiaryls.
- Rao, Maddali L.N.,Meka, Suresh
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- Cost-effective bio-derived mesoporous carbon nanoparticles-supported palladium catalyst for nitroarene reduction and Suzuki–Miyaura coupling by microwave approach
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A new heterogeneous catalyst was synthesized by immobilizing Pd on areca nut kernel-derived carbon nanospheres (CNSs). The CNSs, without any further activation processes, accommodated 3% of Pd on their surface. The new Pd/CNS material was used for the reduction of nitroarenes and Suzuki–Miyaura coupling of bromoarenes with aryl boronic acids. The reactions were conducted under microwave irradiation at 160 °C using 12 mol% of Pd/CNS (0.36% actual Pd content). The reduction of nitroarenes into their respective amino compounds was achieved in 10–20 min (conversion up to 100%); by contrast, the Suzuki–Miyaura reactions yielded up to 98% at 150 °C with 10 mol% of Pd/CNS catalyst. The products were identified using gas chromatography and nuclear magnetic resonance spectroscopy. The catalyst was isolated from reaction mixture and reused without any significant loss in the activity. Thus, the present work introduces one-pot-derived porous CNSs as efficient catalytic support to Pd, establishing an alternative to existing Pd/C in terms of cost and efficiency.
- Supriya,Ananthnag, Guddekoppa S.,Shetti, Vijayendra S.,Nagaraja,Hegde, Gurumurthy
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- A one-pot protocol for the fluorosulfonation and Suzuki coupling of phenols and bromophenols, streamlined access to biaryls and terphenyls
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A one-pot protocol for the fluorosulfation and Suzuki coupling of phenols is described. The tandem reaction proceeds efficiently at room temperature, and various biaryls and biaryl fluorosulfates were obtained in good to excellent yields. Furthermore, biaryl fluorosulfates were utilized as versatile building blocks for the preparation of terphenyls. The Royal Society of Chemistry 2020.
- Hu, Rui,Li, Xinmin,Ren, Changyue,Yuan, Zeli,Zhang, Hang,Zhang, Tingting
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supporting information
p. 4748 - 4753
(2020/08/17)
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- COMPOUNDS AND METHODS FOR TREATING OXALATE-RELATED DISEASES
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Disclosed herein are compounds and compositions for modulating glycolate oxidase, useful for treating oxalate-related diseases, such as hyperoxaluria, where modulating glycolate oxidase is expected to be therapeutic to a patent in need thereof. Methods of modulating glycolate oxidase activity in a human or animal subject is also provided.
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Paragraph 0248; 0280; 0282
(2019/09/12)
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- Experimental evidence for the formation of cationic intermediates during iodine(iii)-mediated oxidative dearomatization of phenols
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Iodine(iii)-based oxidants are commonly used reagents for the oxidative dearomatization of phenols. Having a better understanding of the mechanism through which these reactions proceed is important for designing new iodine(iii)-based reagents, catalysts, and reactions. We have performed a Hammett analysis of the oxidative dearomatization of substituted 4-phenylphenols. This study confirms that iodine(iii)-mediated oxidative dearomatizations likely proceed through cationic phenoxenium ions and not the direct addition of a nucleophile to an iodine-bound phenol intermediate.
- Tang, Ting,Harned, Andrew M.
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p. 6871 - 6874
(2018/10/02)
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- Nickel-Catalyzed Cyanation of Phenol Derivatives with Zn(CN)2 Involving C-O Bond Cleavage
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An efficient nickel-catalyzed cyanation of aryl sulfonates, fluorosulfonates, and sulfamates with Zn(CN)2 was developed, which provides a facile access to the nitrile products in generally good to excellent yields. The reaction is accomplished by using NiII complex as the precatalyst and DMAP as the additive. The method also displays wide functional group compatibility; for example, keto, methoxy, N,N-dimethylamino, cyano, ester, and pyridyl groups are well-tolerated during the reaction process.
- Gan, Yi,Wang, Gaonan,Xie, Xin,Liu, Yuanhong
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p. 14036 - 14048
(2018/11/03)
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- An acetatopalladium(II) complex with 1-benzyl-N-(3,5-di-tert-butylsalicylidene)piperidin-4-amine: Synthesis, structure and catalytic applications in Suzuki–Miyaura coupling of arylboronic acids with hydroxyaryl halides
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The Schiff base 1-benzyl-N-(3,5-di-tert-butylsalicylidene)piperidin-4-amine (HL) and its acetatopalladium(II) complex having the formula [Pd(L)(OAc)] were synthesized. Both HL and [Pd(L)(OAc)] were characterized using elemental analysis and various spectroscopic (infrared, UV–visible, 1H NMR and 13C NMR) and mass spectrometric measurements. The molecular structure of the complex was determined using X-ray crystallographic analysis. In the complex, the pincer-like NNO-donor L? and the monodenate OAc? provide a distorted square-planar N2O2 coordination environment around the metal centre. The physicochemical properties and the spectroscopic features of [Pd(L)(OAc)] are consistent with its molecular structure. The complex was found to be an effective catalyst for the Suzuki–Miyaura cross-coupling reactions of hydroxyaryl halides with arylboronic acids in predominantly aqueous media. The reactions afforded hydroxybiaryl products in good to excellent yields with a wide substrate scope.
- Keesara, Srinivas,Narendra Babu,Pal, Samudranil
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- A highly efficient and reusable palladium(II)/cationic 2,2′-bipyridyl-catalyzed stille coupling in water
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A water-soluble PdCl2 (NH3 )2 /cationic 2,2′ -bipyridyl system was found to be a highly efficient catalyst for Stille coupling of aryl iodides and bromides with organostannanes. The coupling reaction was conducted at 110°C in water, under aerobic conditions, in the presence of NaHCO3 as a base to afford corresponding Stille coupling products in good to high yields. When aryltributylstannanes were employed, the reactions proceeded smoothly under a very low catalyst loading (as little as 0.0001 mol %). After simple extraction, the residual aqueous phase could be reused in subsequent runs, making this Stille coupling economical. In the case of tetramethylstannane, however, a greater catalyst loading (1 mol %) and the use of tetraethylammonium iodide as a phase-transfer agent were required in order to obtain satisfactory yields.
- Wu, Wei-Yi,Liu, Ling-Jun,Chang, Fen-Ping,Cheng, Yu-Lun,Tsai, Fu-Yu
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- Imidazo oxazine derivatives, pharmaceutically acceptable salts thereof or optical isomer thereof and pharmaceutical composition containing the same as an active ingredient
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The present invention relates to imidazo oxazine derivatives, pharmaceutically acceptable salt thereof or optical isomer thereof, and a pharmaceutical composition comprising the same as an effective component. Derivatives of 2-nitro-6,7-dihydroimidazole[2,1-b][1,3]oxazine of which the seventh position is substituted, and pharmaceutically acceptable salt thereof, or optical isomer thereof, have excellent effect of inhibiting tubercular bacillus, specifically inactive tubercular bacillus, thus are useful to use as a pharmaceutical composition comprising the same as effective components for treating tuberculosis.COPYRIGHT KIPO 2016
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Paragraph 0405-0409
(2016/10/09)
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- PEG Click-Triazole Palladacycle: An Efficient Precatalyst for Palladium-Catalyzed Suzuki-Miyaura and Copper-free Sonogashira Reactions in Neat Water
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A novel water-soluble, phosphine-free PEG click triazole palladacycle has been successfully synthesized. As a precatalyst, the palladacycle exhibited superior catalytic activity towards Suzuki-Miyaura and copper-free Sonogashira cross-coupling in neat water with the turnover numbers (TONs) of up to 9.8×105. In addition, the catalyst could be reused at least 3 times without significant loss of reactivity. A water-soluble PEG click triazole palladacycle has been successfully synthesized. The palladacycle exhibited superior catalytic activity towards Suzuki-Miyaura and copper-free Sonogashira cross-coupling in neat water.
- Zhang, Guofu,Zhang, Wei,Luan, Yuxin,Han, Xingwang,Ding, Chengrong
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supporting information
p. 705 - 710
(2015/12/05)
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- Pd nanoparticle-silica nanotubes (Pd@SNTs) as an efficient catalyst for Suzuki-Miyaura coupling and sp2 C-H arylation in water
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Silica nanotubes (SNTs) functionalized with Pd-NPs on the inner surface performed as efficient nano-reactors for C-C coupling in water; the nano-confinement offers minimized leaching of Pd and yet efficient mass transfer for Suzuki-Miyaura coupling and C-H arylation of thiazoles in water with very high TON.
- Park, Ginam,Lee, Sanghee,Son, Sang Jun,Shin, Seunghoon
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supporting information
p. 3468 - 3473
(2013/12/04)
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- A convenient chemical-microbial method for developing fluorinated pharmaceuticals
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A significant proportion of pharmaceuticals are fluorinated and selecting the site of fluorine incorporation can be an important beneficial part a drug development process. Here we describe initial experiments aimed at the development of a general method of selecting optimum sites on pro-drug molecules for fluorination, so that metabolic stability may be improved. Several model biphenyl derivatives were transformed by the fungus Cunninghamella elegans and the bacterium Streptomyces griseus, both of which contain cytochromes P450 that mimic oxidation processes in vivo, so that the site of oxidation could be determined. Subsequently, fluorinated biphenyl derivatives were synthesised using appropriate Suzuki-Miyaura coupling reactions, positioning the fluorine atom at the pre-determined site of microbial oxidation; the fluorinated biphenyl derivatives were incubated with the microorganisms and the degree of oxidation assessed. Biphenyl-4-carboxylic acid was transformed completely to 4′-hydroxybiphenyl-4-carboxylic acid by C. elegans but, in contrast, the 4′-fluoro-analogue remained untransformed exemplifying the microbial oxidation-chemical fluorination concept. 2′-Fluoro- and 3′-fluoro-biphenyl-4-carboxylic acid were also transformed, but more slowly than the non-fluorinated biphenyl carboxylic acid derivative. Thus, it is possible to design compounds in an iterative fashion with a longer metabolic half-life by identifying the sites that are most easily oxidised by in vitro methods and subsequent fluorination without recourse to extensive animal studies.
- Bright, Tara V.,Dalton, Fay,Elder, Victoria L.,Murphy, Cormac D.,O'Connor, Neil K.,Sandford, Graham
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p. 1135 - 1142
(2013/03/28)
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- Metallomicelles of palladium(II) complexes as efficient catalysts for the Suzuki-Miyaura reaction in neat water
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Metallomicelles of palladium(II) complex 4 are found to be an efficient catalyst for Suzuki-Miyaura reactions of aryl bromides substituted with a long alkyl chain and arylboronic acids at 80 °C in neat water. The reactions proceed smoothly to generate the corresponding biaryl compounds in moderate to excellent yields. Various biphenyl derivatives were successfully obtained by complex 4 catalysis of the Suzuki-Miyaura reactions in the absence of any surfactants in neat water. Copyright
- Liu, Yan,Ma, Xiaowei,Xie, Jianwei,Liu, Ping,Dai, Bin,He, Ren
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p. 494 - 498
(2013/08/23)
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- Design, synthesis, and anti-proliferative evaluation of [1,1′-biphenyl]-4-ols as inhibitor of HUVEC migration and tube formation
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Allylated biphenol neolignans contain a variety of chemopreventive entities that have been used as anti-tumor drug leads. Herein, 37 allylated biphenols were evaluated for anti-proliferative activity by the MTT assay and inhibitory effect on the migration and tube formation of HUVECs featuring anti-angiogenic properties. 3-(2-Methylbut-3-en-2-yl)-3′,5′-bis(trifluoromethyl)-[1, 1′-biphenyl]-4-ol (5c) exerted an inhibitory effect on HUVECs compared to honokiol (IC50 = 47.0 vs. 52.6 μM) and showed significant blocking effects on the proliferation of C26, Hela, K562, A549, and HepG2 (IC 50 = 15.0, 25.0, 21.2, 29.5, and 13.0 μM, respectively), superior to those of honokiol (IC50 = 65.1, 62.0, 42.0, 75.0, and 55.4 μM, respectively). Importantly, compound 5c inhibited the migration and capillary-like tube formation of HUVECs in vitro.
- Ran, Yan,Ma, Liang,Wang, Xuewei,Chen, Jinying,Wang, Guangcheng,Peng, Aihua,Chen, Lijuan
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experimental part
p. 8091 - 8104
(2012/10/07)
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- Palladium nanoparticles supported on SiO2 by chemical vapor deposition (CVD) technique as efficient catalyst for Suzuki-Miyaura coupling of aryl bromides and iodides: Selective coupling of halophenols
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Nanoparticles of palladium were supported on SiO2 by chemical vapor deposition technique. The obtained Pd nanocatalyst was characterized by various techniques. This catalyst was found to be very efficient for the selective cross-coupling of hydroxyl-substituted aryl iodides and bromide with arylboronic acids in water at room temperature to produce the corresponding hydroxyl-substituted biaryls. Coupling of phenylboronic acid with aryl iodides and bromides carrying substituents other than hydroxy group was also performed efficiently in refluxing ethanol. Copyright 2012 John Wiley & Sons, Ltd. Palladium nanoparticles supported on SiO2 as an efficient heterogeneous catalyst was prepared by CVD technique and applied in Suzuki coupling reaction mild conditions. The Suzuki reaction of halophenols was conducted at room temperature in the presence of this catalyst. Copyright
- Iranpoor, Nasser,Firouzabadi, Habib,Safavi, Afsaneh,Motevalli, Somayeh,Doroodmand, Mohammad M.
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experimental part
p. 417 - 424
(2012/09/22)
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- Microwave-assisted aqueous Suzuki coupling reactions catalyzed by ionic palladium(II) complexes
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Suzuki coupling is one of the most powerful methods for the synthesis of biaryls. We have prepared and characterized a series of unsymmetrical sulfonated watersoluble Pd(II)-pyridyl imine complexes and investigated them as catalysts for the Suzuki cross-coupling reaction in water under microwave irradiation. The compounds proved to be effective catalysts. Springer Science+Business Media B.V. 2011.
- Hanhan, M. Emre,Senemoglu, Yetkin
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experimental part
p. 109 - 116
(2012/08/28)
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- Structural modification of honokiol, a biphenyl occurring in magnolia officinalis: The evaluation of honokiol analogues as inhibitors of angiogenesis and for their cytotoxicity and structure-activity relationship
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Honokiol, widely known as an antitumor agent, has been used as an antiangiogenesis drug lead. In this paper, 47 honokiol analogues and derivatives were investigated for their antiangiogenic activity by application of the transgenic zebrafish screening model, antiproliferative and cytotoxic activity against HUVECs, and three tumor cell lines by MTT assay. 3′,5-Diallyl-2, 4′-dihydroxy-[1,1′-biphen-yl]-3,5′-dicarbaldehyde (8c) was found to suppress the newly grown segmental vessels from the dorsal aorta of zebrafish and prevent inappropriate vascularization as well as exhibit more potent inhibitory effects on the proliferation of HUVECs, A549, HepG2, and LL/2 cells (IC50 = 15.1, 30.2, 10.7, and 21.7 μM, respectively) than honokiol (IC50 = 52.6, 35.0, 16.5, and 65.4 μM, respectively). Analogue 8c also effectively inhibited the migration and capillary-like tube formation of HUVECs in vitro. The antiangiogenic effect and antiproliferative activity of these structurally modified honokiol analogues and derivatives have led to the establishment of a structure-activity relationship.
- Ma, Liang,Chen, Jinying,Wang, Xuewei,Liang, Xiaolin,Luo, Youfu,Zhu, Wei,Wang, Tianen,Peng, Ming,Li, Shucai,Jie, Shi,Peng, Aihua,Wei, Yuquan,Chen, Lijuan
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experimental part
p. 6469 - 6481
(2011/12/01)
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- An efficient protocol for the palladium-catalysed Suzuki-Miyaura cross-coupling
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The palladacyclic catalyst precursor received by ortho-palladation of ([1,1′-biphenyl]-2-yloxy)diisopropyl-phosphine represents a highly active system for Suzuki-Miyaura cross-coupling reactions when used in neat water. An efficient, broadly applicable and sustainable aqueous protocol was developed using 2.5 eq. of Na2CO3 as base, allowing the reaction to be performed under air and at ambient temperature with Pd loadings of 0.04 mol%. Coupling products are obtained in high yields and excellent purity by simple filtration with no organic solvents needed throughout the whole reaction. A broad variety of functional groups are tolerated and a large number of substrates can be applied with this protocol. The crystal structure of the palladacyclic catalyst precursor is presented as well as investigations targeting the nature of catalyst activation and the active catalytic species.
- Marziale, Alexander N.,Jantke, Dominik,Faul, Stefan H.,Reiner, Thomas,Herdtweck, Eberhardt,Eppinger, Joerg
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supporting information; experimental part
p. 169 - 177
(2011/03/23)
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- Suzuki-Miyaura cross coupling reactions with Phenoldiazonium salts
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The Suzuki-Miyaura coupling of phenol diazonium salts and aryl trifluoroborates yields 4-hydroxybiaryls in a protecting group-free synthesis. The Royal Society of Chemistry 2011.
- Schmidt, Bernd,Hoelter, Frank
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supporting information; experimental part
p. 4914 - 4920
(2011/08/06)
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- Bis(imino)pyridine palladium(II) complexes as efficient catalysts for the Suzuki-Miyaura reaction in water
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Bis(imino)pyridine palladium(II) complexes 3 and 4 of type [PdCl(L)PF 6] are found to be efficient catalysts for Suzuki-Miyaura reactions of aryl halides and arylboronic acids. The reactions proceed smoothly to generate the corresponding biaryl compounds in moderate to excellent yields. The synthesis of various fluorinated biphenyl derivatives was successfully achieved by the complex 4 catalyzed the Suzuki-Miyaura reaction in the presence of surfactants bearing a long alkyl chain. Copyright
- Liu, Ping,Yan, Mei,He, Ren
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experimental part
p. 131 - 134
(2010/11/04)
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- Desymmetrization of cyclohexadienones via bronsted acid-catalyzed enantioselective oxo-michael reaction
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Chemical Reaction Reprentation Desymmetrlzatlon of cyclohexadlenones via enantloselectlve oxo-Mlchael reaction catalyzed by chlral phosphoric add to afford highly enantloenrlched 1,4-dloxane and tetrahydrofuran derivatives In excellent yields has been realized. The newly established methodology allows the facile enantloselectlve synthesis of clerolndlclns C, D, and F.Copyright
- Gu, Qing,Rong, Zi-Qiang,Zheng, Chao,You, Shu-Li
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supporting information; experimental part
p. 4056 - 4057
(2010/05/01)
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- Fragment-based substrate activity screening method for the identification of potent inhibitors of the Mycobacterium tuberculosis phosphatase PtpB
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A new substrate-based fragment approach for the identification of novel PTP inhibitors is presented. This method was applied to Mycobacterium tuberculosis PtpB, a promising new target for the treatment of tuberculosis. This resulted in the development of the most potent PtpB inhibitor reported to date (0.22 μM) with low molecular weight and good selectivity against a panel of other protein tyrosine phosphatases. Copyright
- Soellner, Matthew B.,Rawls, Katherine A.,Grundner, Christoph,Alber, Tom,Ellman, Jonathan A.
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p. 9613 - 9615
(2008/02/13)
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- Design, synthesis, and evaluation of 2-alkoxydihydrocinnamates as PPAR agonists
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A series of 2-alkoxydihydrocinnamates were synthesized as PPARγ and PPARα dual agonists. In vitro studies in cell model showed that these compounds were efficacious. Compound 1g was found to be a potent PPARα/γ dual agonist and will be further evaluated for the treatment of type II diabetes.
- Lu, Ying,Guo, Zongru,Guo, Yanshen,Feng, Jun,Chu, Fengming
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p. 915 - 919
(2007/10/03)
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- Synthesis of 18F-labelled biphenyls via SUZUKI cross-coupling with 4-[18F]fluoroiodobenzene
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The SUZUKI reaction of organoboron compounds with 4-[18F] fluoroiodobenzene has been developed as a novel radiolabelling technique in 18F chemistry. The cross-coupling reaction of p-tolylboronic acid with 4-[18F]fluoroiodobenzene was used to screen different palladium complexes, bases and solvents. Optimized reaction conditions (Pd 2(dba)3, Cs2CO3, acetonitrile, 60°C for 5 min) were further applied to the synthesis of various 18F-labelled biphenyls bearing different functional groups. The reaction proceeded in excellent radiochemical yields of up to 94% within 5 min while showing good compatibility to many functional groups. Copyright
- Steiniger, Bjoern,Wuest, Frank R.
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p. 817 - 827
(2007/10/03)
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- Recyclable and highly active cationic 2,2′-bipyridyl palladium(II) catalyst for Suzuki cross-coupling reaction in water
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A water-soluble and air-stable palladium(II)/cationic 2,2′-bipyridyl catalyst is proven to be a recyclable and extremely active catalyst for Suzuki reaction in aqueous and aerobic conditions. The conveniently prepared catalyst showed little loss in the catalytic process of the coupling between 4-bromoacetophenone and phenylboronic acid after five cycles. For the reactions of aryl chlorides, biaryls were formed in high yields under refluxing temperature in the presence of TBAB.
- Wu, Wei-Yi,Chen, Shao-Nung,Tsai, Fu-Yu
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p. 9267 - 9270
(2008/02/10)
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- ERbeta ligands. Part 1: the discovery of ERbeta selective ligands which embrace the 4-hydroxy-biphenyl template.
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The synthesis and structure-activity relationships of a series of simple biphenyls is described. Optimization of the 4-hydroxy-biphenyl template led to compounds with ERbeta selectivity on the order of 20-70-fold.
- Edsall Jr., Richard J,Harris, Heather A,Manas, Eric S,Mewshaw, Richard E
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p. 3457 - 3474
(2007/10/03)
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- Pd/C as a reusable catalyst for the coupling reaction of halophenols and arylboronic acids in aqueous media
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Pd/C was found to catalyze the Suzuki-Miyaura coupling reaction of halophenols in aqueous media. When halophenols were treated with ArB(OH)2 and a catalytic amount of 10% Pd/C (0.3 mol % Pd) in aqueous K2CO3 solution, the corresponding hydroxybiaryls were obtained in a high yield or quantitatively. The palladium catalyst was easily recovered and reused.
- Sakurai, Hidehiro,Tsukuda, Tatsuya,Hirao, Toshikazu
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p. 2721 - 2722
(2007/10/03)
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- Cross-coupling reactions with boronic acids in water catalysed by oxime-derived palladacycles
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Palladacycles derived from phenone-oximes 1 are efficient precatalysts for the Suzuki-Miyaura coupling of arylboronic acids with aromatic and heteroaromatic bromides and chlorides under water reflux under aerobic conditions. Alternatively, the coupling can also be carried out at room temperature in methanol-water. Aryl bromides gave biaryls with TON up to 105 and TOF up to 7 × 104 h-1. Activated and deactivated aryl chlorides need the presence of TBAB for the couplings, showing slightly lower efficiency (TON up to 9000 and TOF up to 3850 h-1). C(sp2)-C(sp3) bonds can also be formed by cross-coupling reactions of trimethylboroxine and butylboronic acid with aromatic bromides and chlorides under water reflux and of benzylic and allylic chlorides or acetates with arylboronic acids in acetone-water at room temperature.
- Botella, Luis,Nájera, Carmen
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- Palladium-tetraphosphine complex: An efficient catalyst for allylic substitution and Suzuki cross-coupling
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A new tetraphosphine, the cis-cis-cis-1,2,3,4-tetrakis (diphenylphosphinomethyl)cyclopentane (Tedicyp) has been synthesized and used in palladium-catalyzed reactions. This tetraphosphine in combination with [Pd(C3H5)Cl]2 affords a very efficient catalyst for coupling reactions. Turnover numbers of 980 000 for allylic amination, 9 800 000 for allylic alkylation and 97 000 000 for Suzuki cross-coupling can be obtained in the presence of this catalyst.
- Feuerstein,Laurenti,Doucet,Santelli
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p. 2320 - 2326
(2007/10/03)
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- Palladium-tetraphosphine catalysed cross coupling of aryl bromides with arylboronic acids: Remarkable influence of the nature of the ligand
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The cis, cis, cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane- [PdCl(C3H5)]2 system catalyses the cross coupling of aryl bromides with arylboronic acids with very high substrate-catalyst ratios in good yields; a turnover number of 28 000 000 can be obtained for the addition of 4-bromobenzophenone to benzeneboronic acid in the presence of this catalyst.
- Feuerstein,Laurenti,Bougeant,Doucet,Santelli
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p. 325 - 326
(2007/10/03)
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- Biphenyl hydroxamate inhibitors of matrix metalloproteinases
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Compounds of formula STR1 or a pharmaceutically acceptable salt thereof inhibit matrix metalloproteinases and TNFα secretion and are useful in the treatment of inflammatory disease states. Also disclosed are matrix metalloproteinases and TNFα secretion inhibiting compositions and a method for inhibiting matrix metalloproteinases and TNFα secretion.
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- Discovery of potent nonpeptide inhibitors of stromelysin using SAR by NMR
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With the use of an NMR-based method, potent (IC50 25 nM) nonpeptide inhibitors of the matrix metalloproteinase stromelysin (MMP-3) were discovered. The method, called SAR by NMR (for structure-activity relationships by nuclear magnetic resonance), involves the identification, optimization, and linking of compounds that bind to proximal sites on a protein. Using this technique, two ligands that bind weakly to stromelysin (acetohydroxamic acid, K(D) = 17 mM; 3-(cyanomethyl)-4'-hydroxybiphenyl, K(D) = 0.02 mM) were identified. On the basis of NMR-derived structural information, the two fragments were connected to produce a 15 nM inhibitor of this enzyme. This compound was rapidly discovered (less than 6 months) and required only a minimal amount of chemical synthesis. These studies indicate that the SAR by NMR method can be effectively applied to enzymes to yield potent lead inhibitors-an important part of the drug discovery process.
- Hajduk,Sheppard,Nettesheim,Olejniczak,Shuker,Meadows,Steinman,Carrera Jr.,Marcotte,Severin,Walter,Smith,Gubbins,Simmer,Holzman,Morgan,Davidsen,Summers,Fesik
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p. 5818 - 5827
(2007/10/03)
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- Mechanisms of the photochemical rearrangement of diphenyl ethers
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The mechanism of the photochemical rearrangement of diphenyl ether (1a) was studied. Irradiation of 1a in ethanol gave 2-phenylphenol (2, 42%) and 4-phenylphenol (3, 11%) as rearrangement products, in addition to phenol (4, 30%) and benzene (5, 25%) as diffusion products. Cross-coupling experiments employing [2H10]1a demonstrated that the formation of 2- and 4-phenylphenol was an intramolecular process. Irradiation of 1a in benzene or in toluene gave biphenyls in good yields. The combined yields of rearrangement products (2 and 3) increased with increase of solvent viscosity, with a concomitant decrease in the formation of 4. All the results can be rationalized in terms of excitation of 1a to the singlet state and dissociation to a radical pair intermediate involving phenoxy and phenyl radicals. Intramolecular recombination of these radicals gives rearrangement products, and escape followed by hydrogen abstraction from the solvent gives diffusion products. When position 4 of 1a was occupied by an electron-donating substituent (1b-e), aryloxy-phenyl bond cleavage to give the corresponding rearrangement products prevailed over phenoxy-aryl bond cleavage. The opposite was the case for substrates with an electron-withdrawing substituent at position 4 (1h,i).
- Haga, Naoki,Takayanagi, Hiroaki
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p. 735 - 745
(2007/10/03)
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- Arylation of Phenols. Convenient, Regiospecific Methods for Mono- or Bis-p-fluorophenylations, Suitable for Large Scale Syntheses
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Phenols have been arylated by a palladium(0)-catalyzed coupling reaction.Two methods were used: a Grignard reagent of a protected phenol component 2 was coupled with a haloarene, or an umpolung (reversed reactivity) where unprotected phenolic halides 6 were coupled with aryl Grignard reagents.Bis-arylation and regiospecific ortho-, meta- and para-arylations were achieved.Aryl-aryl-couplings were insensitive to steric hindrance in the Grignard component, but were inhibited by sulfur-containing substituents in the phenolic component.A thiocyanate substituted biaryl was used to synthesize arylated phenols with various sulfur functionalities.
- Jendralla, Heiner,Chen, Li-Jian
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p. 827 - 833
(2007/10/02)
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- Activation of Reducing Agents. Sodium Hydride Containing Complex Reducing Agents. 32. NiCRAL's as Very Efficient Agents in Promoting Cross-Coupling of Aryl Halides
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Nickel-containing complex reducing agents NiCRA-bpy are shown to be the first nickel reagents able to efficiently perform cross-coupling of aryl halides.The presence of KI in the reaction medium generally improves the procedure.The mechanism and influence of the structures of the substrates are discused.
- Lourak, Mouhsine,Vanderesse, Regis,Fort, Yves,Caubere, Paul
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p. 4844 - 4848
(2007/10/02)
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- F-NMR-spectroscopy for the identification of photo products generated from aromatic iodo compounds - IV
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The investigation demonstrates the analytical power of F-NMR spectroscopy for the identification of isomeric substituted fluorobiphenyls.The biphenyls are formed by u.v. irradiation of iodobenzenes in aromatic solvents.A special procedure for the identification is outlined and tendencies of the results-chemical shifts and relative rates for the production of isomers-are discussed in consideration of electronic and steric substituent effects.
- Kelm, J.,Strauss, K.
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p. 689 - 692
(2007/10/02)
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