- Dilithium Amides as a Modular Bis-Anionic Ligand Platform for Iron-Catalyzed Cross-Coupling
-
Dilithium amides have been developed as a bespoke and general ligand for iron-catalyzed Kumada-Tamao-Corriu cross-coupling reactions, their design taking inspiration from previous mechanistic and structural studies. They allow for the cross-coupling of alkyl Grignard reagents with sp2-hybridized electrophiles as well as aryl Grignard reagents with sp3-hybridized electrophiles. This represents a rare example of a single iron-catalyzed system effective across diverse coupling reactions without significant modification of the catalytic protocol, as well as remaining operationally simple.
- Neate, Peter G.N.,Zhang, Bufan,Conforti, Jessica,Brennessel, William W.,Neidig, Michael L.
-
supporting information
p. 5958 - 5963
(2021/08/18)
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- Enabling Metallophotoredox Catalysis in Parallel Solution-Phase Synthesis Using Disintegrating Reagent Tablets
-
Compressed tablets containing a mixture of a photocatalyst, a nickel catalyst, an inorganic base, and an inert excipient are employed as a fast, safe, and user-friendly chemical delivery system for two different metallophotoredox-catalyzed reactions. This delivery method simplifies the preparation of compound libraries using photoredox chemistry in a parallel setting. The reagent tablets were successfully applied to late-stage functionalization of drug-like intermediates. These tablets can be prepared with various reagents and catalysts in different sizes and be stored on the bench thanks to blister packaging.
- Borlinghaus, Niginia,Sch?nfeld, Barbara,Heitz, Stephanie,Klee, Johanna,Vukeli?, Stella,Braje, Wilfried M.,Jolit, Anais
-
supporting information
p. 16535 - 16547
(2021/12/02)
-
- Oxidative esterification of alcohols by a single-side organically decorated Anderson-type chrome-based catalyst
-
The direct esterification of alcohols with non-noble metal-based catalytic systems faces great challenges. Here, we report a new chrome-based catalyst stabilized by a single pentaerythritol decorated Anderson-type polyoxometalate, [N(C4H9)4]3[CrMo6O18(OH)3C{(OCH2)3CH2OH}], which can realize the efficient transformation from alcohols to esters by H2O2oxidation in good yields and high selectivity without extra organic ligands. A variety of alcohols with different functionalities including some natural products and pharmaceutical intermediates are tolerated in this system. The chrome-based catalyst can be recycled several times and still keep the original configuration and catalytic activity. We also propose a reasonable catalytic mechanism and prove the potential for industrial applications.
- Wang, Jingjing,Jiang, Feng,Tao, Chaofu,Yu, Han,Ruhlmann, Laurent,Wei, Yongge
-
supporting information
p. 2652 - 2657
(2021/04/21)
-
- 5-Phenyl-1,3,4-oxadiazol-2(3 H)-ones Are Potent Inhibitors of Notum Carboxylesterase Activity Identified by the Optimization of a Crystallographic Fragment Screening Hit
-
Carboxylesterase Notum is a negative regulator of the Wnt signaling pathway. There is an emerging understanding of the role Notum plays in disease, supporting the need to discover new small-molecule inhibitors. A crystallographic X-ray fragment screen was performed, which identified fragment hit 1,2,3-Triazole 7 as an attractive starting point for a structure-based drug design hit-To-lead program. Optimization of 7 identified oxadiazol-2-one 23dd as a preferred example with properties consistent with drug-like chemical space. Screening 23dd in a cell-based TCF/LEF reporter gene assay restored the activation of Wnt signaling in the presence of Notum. Mouse pharmacokinetic studies with oral administration of 23dd demonstrated good plasma exposure and partial blood-brain barrier penetration. Significant progress was made in developing fragment hit 7 into lead 23dd (>600-fold increase in activity), making it suitable as a new chemical tool for exploring the role of Notum-mediated regulation of Wnt signaling.
- Mahy, William,Willis, Nicky J.,Zhao, Yuguang,Woodward, Hannah L.,Svensson, Fredrik,Sipthorp, James,Vecchia, Luca,Ruza, Reinis R.,Hillier, James,Kj?r, Svend,Frew, Sarah,Monaghan, Amy,Bictash, Magda,Salinas, Patricia C.,Whiting, Paul,Vincent, Jean-Paul,Jones, E. Yvonne,Fish, Paul V.
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p. 12942 - 12956
(2020/11/13)
-
- Palladium-Catalyzed Chlorocarbonylation of Aryl (Pseudo)Halides Through In Situ Generation of Carbon Monoxide
-
An efficient palladium-catalyzed chlorocarbonylation of aryl (pseudo)halides that gives access to a wide range of carboxylic acid derivatives has been developed. The use of butyryl chloride as a combined CO and Cl source eludes the need for toxic, gaseous carbon monoxide, thus facilitating the synthesis of high-value products from readily available aryl (pseudo)halides. The combination of palladium(0), Xantphos, and an amine base is essential to promote this broadly applicable catalytic reaction. Overall, this reaction provides access to a great variety of carbonyl-containing products through in situ transformation of the generated aroyl chloride. Combined experimental and computational studies support a reaction mechanism involving in situ generation of CO.
- Bismuto, Alessandro,Boehm, Philip,Morandi, Bill,Roediger, Sven
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p. 17887 - 17896
(2020/08/19)
-
- Novel Class of Colony-Stimulating Factor 1 Receptor Kinase Inhibitors Based on an o-Aminopyridyl Alkynyl Scaffold as Potential Treatment for Inflammatory Disorders
-
Colony-stimulating factor 1 receptor (CSF-1R) is involved in inflammatory disorders as well as in many types of cancer. Based on high-throughput screening and docking results, we performed a detailed structure-activity-relationship study, leading to the d
- Xie, Zhicheng,Wu, Bing,Liu, Yingqiang,Ren, Wenming,Tong, Linjiang,Xiang, Caigui,Wei, Aihuan,Gao, Yuanzhuo,Zeng, Limin,Xie, Hua,Tang, Wei,Hu, Youhong
-
p. 1397 - 1414
(2020/02/04)
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- Aerobic Oxidative Cleavage and Esterification of C(OH)–C Bonds
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C(OH)–C bonds are widely distributed in naturally renewable biomass, such as carbohydrates, lignin, and their platform molecules. Selective cleavage and functionalization of C(OH)–C bonds is an attractive strategy in terms of producing value-added chemicals from biomass. However, effective transformation of alcohols into esters by activation of C(OH)–C bonds has not been achieved so far. Herein, for the first time, we report selective cleavage and esterification of C(OH)–C bonds, catalyzed by inexpensive copper salts, using environmentally benign oxygen as the oxidant, to afford methyl esters in excellent yields. A diverse range of phenylethanol derivatives that contain C(OH)–C bonds were effectively converted into methyl benzoates. Detailed analysis revealed that the high efficiency and selectivity resulted mainly from the fact that, in addition to the major esterification reaction, the side products (e.g., olefins and acids) were also transformed in situ into esters in the reaction system. C(OH)–C bonds are widely distributed in naturally renewable biomass. In the context of developing future biorefineries, selective cleavage and functionalization of C(OH)–C bonds are crucial and represent an attractive strategy in terms of producing value-added chemical compounds from biomass resources. In the current manuscript, we report, for the first time, an effective and selective method for the cleavage and esterification of C(OH)–C bonds of alcohols to produce esters, by using environmentally benign O2 as the terminal oxidant and inexpensive commercially available copper salts as catalysts. Furthermore, a detailed mechanistic study revealed that, in addition to the major esterification route, side products (e.g., olefins and acids), which are inevitably generated under oxidative and basic conditions, were also simultaneously converted into esters, thus significantly improving the final yields of target ester products. Native lignin represents the only naturally sustainable aromatic resource. Transformation of native lignin into valuable aromatics would make a great contribution to our planet. We report, for the first time, the effective transformation of alcohols into esters by esterification of C(OH)–C bonds, which offers a new way for the simultaneous degradation and functionalization of lignin. This reaction promotes new explorations for biomass valorization.
- Liu, Mingyang,Zhang, Zhanrong,Yan, Jiang,Liu, Shuaishuai,Liu, Huizhen,Liu, Zhaotie,Wang, Weitao,He, Zhenhong,Han, Buxing
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p. 3288 - 3296
(2020/10/20)
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- Aldehydes as potential acylating reagents for oxidative esterification by inorganic ligand-supported iron catalysis
-
The oxidative esterification of various aldehydes with alcohols could be achieved by a heterogeneous iron(iii) catalyst supported on a ring-like POM inorganic ligand under mild conditions, affording the corresponding esters, including several drug molecules and natural products, in high yields. ESI-MS and control experiments demonstrated that POM-FeV(O) was the active catalytic species and the plausible mechanism was presented. More importantly, the 6th run of the iron catalyst recycles shows only a slight decrease in the yield.
- Yu, Han,Wang, Jingjing,Wu, Zhikang,Zhao, Qixin,Dan, Demin,Han, Sheng,Tang, Jiangjiang,Wei, Yongge
-
supporting information
p. 4550 - 4554
(2019/08/21)
-
- Chloride-Induced Highly Active Au Catalyst for Methyl Esterification of Alcohols
-
Chloride is generally regarded as a harmful species for the heterogeneous catalysts, especially Au catalysts. In this work, a series of active Au/NiOx catalysts were successfully prepared with co-precipitation method by tracking the concentrations of chloride in the re-dispersed aqueous solutions. For methyl esterification of alcohols, the highest active Au/NiOx catalysts could be prepared from aqueous solutions containing 8-13 ppm chloride, the yield of methyl benzoate of catalyst Au/NiOx-9 was 99%. The catalyst structures and the role of chloride in catalysts were explored by ICP, BET, XPS, TEM and EXAFS characterizations. It was found that the appropriate amount of residual chloride in Au catalysts was beneficial to their catalytic activities. Especially for Au/NiOx-9, the appropriate amount of residual chloride had positive effects on the physicochemical properties of Au/NiOx catalyst, the position of Au nanoparticles (NPs) located on NiOx crystallites and the ratio of Auδ+/Au0 in catalyst, which together resulted in its high reactivity.
- Zhang, Chengming,Wang, Yongzhao
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p. 249 - 254
(2019/02/13)
-
- Deoxygenative cross-electrophile coupling of benzyl chloroformates with aryl iodides
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This work describes Ni-catalyzed cross-electrophile coupling of benzyl chloroformate derivatives with aryl iodides that generates a wide range of diaryl methane products. The mild reaction conditions merit the C-O bond radical fragmentation of benzyl chloroformates via halide abstraction or a single electron reduction by a Ni catalyst. This work offers a new substrate type for cross-electrophile couplings.
- Pan, Yingying,Gong, Yuxin,Song, Yanhong,Tong, Weiqi,Gong, Hegui
-
p. 4230 - 4233
(2019/05/06)
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- Methyl Perillate as a Highly Functionalized Natural Starting Material for Terephthalic Acid
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Renewable commodity chemicals can be generated from plant materials. Often abundant materials such as sugars are used for this purpose. However, these lack appropriate functionalities and, therefore, they require extensive chemical modifications before they can be used as commodity chemicals. The plant kingdom is capable of producing an almost endless variety of compounds, including compounds with highly appropriate functionalities, but these are often not available in high quantities. It has been demonstrated that it is possible to produce functionalized plant compounds on a large scale by fermentation in microorganisms. This opens up the potential to exploit plant compounds that are less abundant, but functionally resemble commodity chemicals more closely. To elaborate this concept, we demonstrate the suitability of a highly functionalized plant compound, methyl perillate, as a precursor for the commodity chemical terephthalic acid.
- Jongedijk, Esmer,van der Klis, Frits,de Zwart, Rozemarijn,van Es, Daan S.,Beekwilder, Jules
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p. 201 - 203
(2018/03/06)
-
- Iron-Catalyzed Isopropylation of Electron-Deficient Aryl and Heteroaryl Chlorides
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Traditional methods for the preparation of secondary alkyl-substituted aryl and heteroaryl chlorides challenge both selectivity and functional group tolerance. This contribution describes the use of statistical design of experiments to develop an effective procedure for the preparation of isopropyl-substituted (hetero)arenes with minimal isopropyl to n-propyl isomerization. The reaction tolerates electronically diverse aryl chloride coupling partners, with excellent conversion observed for strongly electron-deficient aromatic rings, such as esters and amides. Electron-rich systems, including methyl- and methoxy-substituted aryl chlorides, were found to be less reactive. Furthermore, the reaction was found to be most successful when heteroaryl chlorides were submitted to the cross-coupling protocol. By mapping substituent effects on reaction selectivity, we were able to show that electron-deficient aryl chlorides are essential for efficient coupling, and use electronic structure calculations to predict the likelihood of successful coupling through the estimation of the electron affinity of each aryl chloride. Moderate isolated yields were achieved with selected aryl chlorides, and moderate to good isolated yields were obtained for all the heteroaryl chlorides coupled. Excellent selectivity was observed when a 2,6-dichloroquinoline was used, allowing mono-substitution on a challenging substrate. (Figure presented.).
- Sanderson, James N.,Dominey, Andrew P.,Percy, Jonathan M.
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p. 1007 - 1017
(2017/03/27)
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- Single-electron transmetalation: An enabling technology for secondary alkylboron cross-coupling
-
Single-electron-mediated alkyl transfer affords a novel mechanism for transmetalation, enabling cross-coupling under mild conditions. Here, general conditions are reported for cross-coupling of secondary alkyltrifluoroborates with an array of aryl bromides mediated by an Ir photoredox catalyst and a Ni cross-coupling catalyst.
- Primer, David N.,Karakaya, Idris,Tellis, John C.,Molander, Gary A.
-
supporting information
p. 2195 - 2198
(2015/03/04)
-
- Nitrogen enriched mesoporous organic polymer anchored copper(ii) material: An efficient and reusable catalyst for the synthesis of esters and amides from aromatic systems
-
A new copper-grafted mesoporous poly-melamine-formaldehyde (Cu-mPMF) has been synthesized from melamine and paraformaldehyde in DMSO medium, followed by grafting of Cu(ii) at its surface. Cu-mPMF has been characterized by elemental analysis, powder XRD, HR TEM, FE-SEM, N2 adsorption study, FT-IR, UV-vis DRS, TGA-DTA, EPR spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The Cu-grafted mesoporous material showed very good catalytic activity in methyl esterification of benzylic alcohols and amidation of nitriles. Moreover, the catalyst is easily recoverable and can be reused seven times without appreciable loss of catalytic activity in the above reactions. The highly dispersed and strongly bound Cu(ii) sites in the Cu-grafted mesoporous polymer could be responsible for the observed high activities of the Cu-mPMF catalyst. Due to strong binding with the functional groups of the polymer, no evidence of leached copper from the catalyst during the course of reaction emerged, suggesting true heterogeneity in the catalytic process. This journal is
- Molla, Rostam Ali,Iqubal, Md. Asif,Ghosh, Kajari,Kamaluddin,Islam, Sk. Manirul
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p. 6546 - 6559
(2015/04/14)
-
- Upgrading malic acid to bio-based benzoates via a Diels-Alder-initiated sequence with the methyl coumalate platform
-
The conversion of naturally-occurring malic acid to the 2-pyrone methyl coumalate was optimized using a variety of acid catalysts. Coupling methyl coumalate with electron-rich dienophiles in an inverse electron-demand Diels-Alder (IEDDA)/decarboxylation/elimination domino sequence resulted in an investigation of the scope and limitations of the methodology. The thermal, metal-free, and one-pot procedure allows regioselective access to diverse aromatic compounds including tricyclic, biphenyl, and pyridinyl systems for elaboration. A comparison with analogous pyrones demonstrates the striking efficacy of methyl coumalate as a versatile platform for the generation of biorenewable functionalized benzoates. This journal is
- Lee, Jennifer J.,Pollock Iii, Gerald R.,Mitchell, Donald,Kasuga, Lindsay,Kraus, George A.
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p. 45657 - 45664
(2015/02/19)
-
- Copper-catalyzed methyl esterification reactions via C-C bond cleavage
-
The highly effective synthesis of methyl esters from benzylic alcohols, aldehydes, or acids via copper-catalyzed C-C cleavage from tert-butyl hydroperoxide is reported in this paper for the first time. Our protocol is easily accessible and practical, making it a possible supplement for the traditional way.
- Zhu, Yan,Yan, Hong,Lu, Linhua,Liu, Defu,Rong, Guangwei,Mao, Jincheng
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p. 9898 - 9905
(2013/10/22)
-
- The dual role of ionic liquid BmimBF4, precursor of N-heterocyclic carbene and solvent, in the oxidative esterification of aldehydes
-
Room temperature ionic liquid BmimBF4 (1-butyl-3- methylimidazolium tetrafluoroborate) has been utilized in the N-heterocyclic carbene-catalyzed oxidation of aldehydes to yield esters. In the presence of MnO2 as oxidant and of DBU and caesium carbonate as bases, aromatic, heteroaromatic and aliphatic esters have been isolated in good to excellent yields. The recyclability of the used ionic liquid along with the excess of inorganic reagents has been proved. The simple and cheap BmimBF4 ionic liquid played the dual role of precatalyst and solvent. This is the first time that such a reaction has been carried out with an ionic liquid as solvent.
- Chiarotto, Isabella,Feroci, Marta,Sotgiu, Giovanni,Inesi, Achille
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p. 8088 - 8095
(2013/08/23)
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- Selective oxidation of alcohols to esters using heterogeneous Co 3O4-N@C catalysts under mild conditions
-
Novel cobalt-based heterogeneous catalysts have been developed for the direct oxidative esterification of alcohols using molecular oxygen as benign oxidant. Pyrolysis of nitrogen-ligated cobalt(II) acetate supported on commercial carbon transforms typical homogeneous complexes to highly active and selective heterogeneous Co3O4-N@C materials. By applying these catalysts in the presence of oxygen, the cross and self-esterification of alcohols to esters proceeds in good to excellent yields.
- Jagadeesh, Rajenahally V.,Junge, Henrik,Pohl, Marga-Martina,Radnik, Joerg,Brueckner, Angelika,Beller, Matthias
-
supporting information
p. 10776 - 10782
(2013/08/23)
-
- Synthesis, molecular modeling and biological evaluation of 2-(benzylthio)-5-aryloxadiazole derivatives as anti-tumor agents
-
A series of 2-(benzylthio)-5-aryloxadiazole derivatives have been designed and synthesized, and their biological activities are also evaluated for EGFR inhibitory activity. Fourteen compounds among the twenty compounds are reported for the first time. Their chemical structures are characterized by 1H NMR, MS, and elemental analysis. Anti-proliferative and EGFR inhibition assay results have demonstrated that compound 3e shows the most potent biological activity (IC50 = 1.09 μM for MCF-7 and IC50 = 1.51 μM for EGFR). Docking simulation has been performed to position compound 3e into the EGFR active site to determine the probable binding model, with an estimated binding free energy value of -10.7 kcal/mol. Compound 3e with potent inhibitory activity in tumor growth inhibition may be a promising anti-tumor leading compound for the further research.
- Liu, Kai,Lu, Xiang,Zhang, Hong-Jia,Sun, Juan,Zhu, Hai-Liang
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scheme or table
p. 473 - 478
(2012/03/13)
-
- Pd-PEPPSI-IPentCl: A highly effective catalyst for the selective cross-coupling of secondary organozinc reagents
-
No migration? No problem. A series of new N-heterocyclic carbene based Pd complexes has been created and evaluated in the Negishi cross-coupling of aryl and heteroaryl chlorides, bromides, and triflates with a variety of secondary alkylzinc reagents (see scheme). The direct elimination product is nearly exclusively formed; in most examples there is no migratory insertion at all. Copyright
- Pompeo, Matthew,Hadei, Niloufar,Organ, Michael G.,Froese, Robert D. J.
-
supporting information
p. 11354 - 11357,4
(2012/12/12)
-
- Pd-PEPPSI-IPentCl: A highly effective catalyst for the selective cross-coupling of secondary organozinc reagents
-
No migration? No problem! A series of new N-heterocyclic carbene based Pd complexes has been created and evaluated in the Negishi cross-coupling of aryl and heteroaryl chlorides, bromides, and triflates with a variety of secondary alkylzinc reagents (see scheme). The direct elimination product is nearly exclusively formed; in most examples there is no migratory insertion at all. Copyright
- Pompeo, Matthew,Froese, Robert D. J.,Hadei, Niloufar,Organ, Michael G.
-
supporting information
p. 11354 - 11357
(2013/01/15)
-
- A general and efficient zinc-catalyzed oxidation of benzyl alcohols to aldehydes and esters
-
Go green: A general and efficient zinc-catalyzed oxidation of benzyl alcohols has been developed. In the presence of a zinc catalyst, various aldehydes and esters have been prepared in good to excellent yields under mild conditions (see scheme).
- Wu, Xiao-Feng
-
experimental part
p. 8912 - 8915
(2012/09/22)
-
- Negishi cross-coupling of secondary alkylzinc halides with aryl/heteroaryl halides using Pd-PEPPSI-IPent
-
Pd-PEPPSI-IPent has proven to be an excellent catalyst for the Negishi cross-coupling reaction of secondary alkylzinc reagents with a wide variety of aryl/heteroaryl halides. Importantly, β-hydride elimination/migratory insertion of the organometallic leading to the production of isomeric coupling products has been significantly reduced using the highly-hindered Ipent ligand.
- Alimsiz, Seluk,Organ, Michael G.
-
supporting information; experimental part
p. 5181 - 5183
(2011/06/09)
-
- Nickel-catalyzed Negishi cross-coupling reactions of secondary alkylzinc halides and aryl iodides
-
A general Ni-catalyzed process for the cross-coupling of secondary alkylzinc halides and aryl/heteroaryl iodides has been developed. This is the first process to overcome the isomerization and β-hydride elimination problems that are associated with the use of secondary nucleophiles, and that have limited the analogous Pd-catalyzed systems. The impact of salt additives was also investigated. It was found that the presence of LiBF4 dramatically improves both isomeric retention and yield for challenging substrates.(Figure Presented)
- Joshi-Pangu, Amruta,Ganesh, Madhu,Biscoe, Mark R.
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supporting information; experimental part
p. 1218 - 1221
(2011/04/27)
-
- Catalytic oxidative esterification of aldehydes and alcohols using KI-TBHP
-
A simple and mild procedure for the facile oxidative esterification of aldehydes and alcohols using potassium iodide (KI) in combinzation with tert-butyl hydroperoxide (TBHP) as an external oxidant is described. Oxidative esterification is induced by iodine generated in situ by the chemical oxidation of KI with TBHP.
- Reddy, K. Rajender,Venkateshwar,Maheswari, C. Uma,Prashanthi
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experimental part
p. 186 - 195
(2010/03/24)
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- Computational and experimental structure-reactivity relationships: evidence for a side reaction in Alpine-Borane reductions of d-benzaldehydes
-
Extraordinary stereoselectivity, approaching 100%, has been reported in the reductions of d-benzaldehydes by B-isopinocampheyl-9-borabicyclo[3.3.1]nonane (Alpine-Borane). This is likely because of the extreme size disparity of groups on either side of the carbonyl. Here, we present a structure-reactivity study whereby the reductions of variably substituted d-benzaldehydes are explored using highly sensitive measures for enantiomeric excess and relative reactivity. These results are compared to the relative rates predicted from density functional calculations. The results indicate that 2,6-disubstitution adversely affects the stereoselectivity by means of a non-selective reduction via the dehydroboration product of Alpine-Borane, 9-borabicyclo[3.3.1]nonane.
- Zhu, Hui,Soledad Reyes,Meyer, Matthew P.
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supporting information; experimental part
p. 6803 - 6806
(2010/04/29)
-
- Selective oxidation of acetophenones bearing various functional groups to benzoic acid derivatives with molecular oxygen
-
Acetophenones substituted by alkyl, alkoxy, acetoxy, and halogen groups were selectively oxidized with molecular oxygen to the corresponding benzoic acids by using the N,N',N"-trihydroxyisocyanuric acid (THICA)/cobalt(II) acetate [Co(OAc)2] and THICA/Co(OAc)2/manganese(II) acetate.
- Nakamura, Ryota,Obora, Yasushi,Ishii, Yasutaka
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experimental part
p. 1677 - 1684
(2011/02/25)
-
- Photodecarbonylation of ketodiacids as ammonium salts: efficient Formation of C-C bonds between adjacent quaternary centers in the crystalline state
-
Here we report the crystallization and solid photochemistry of six quaternary ammonium salts of 2,4-di-p-carboxyphenyl-2,4-dimethyl pentanone. While salt formation resulted in solids with different melting temperatures and crystallinities, photochemical e
- Family, Farnosh,Garcia-Garibay, Miguel A.
-
experimental part
p. 2476 - 2480
(2009/07/25)
-
- Negishi coupling of secondary alkylzinc halides with aryl bromides and chlorides
-
(Chemical Equation Presented) An efficient palladium-catalyzed process has been developed for Negishi coupling of secondary alkylzinc halides with a wide range of aryl bromides and activated aryl chlorides. A palladium catalyst composed of a new biaryldialkylphosphine ligand, CPhos, effectively promotes the rate of the reductive elimination step relative to the rate of the undesired β-hydride elimination. The broad substrate scope and excellent ratio of the desired secondary to the undesired primary coupling product make this method a powerful and reliable tool forC(sp3)-C(sp2) bond formation.
- Han, Chong,Buchwald, Stephen L.
-
supporting information; experimental part
p. 7532 - 7533
(2009/10/16)
-
- Efficient cross-coupling of secondary alkyltrifluoroborates with aryl chlorides-reaction discovery using parallel microscale experimentation
-
Microscale parallel experimentation was used to discover three catalyst systems capable of coupling secondary organotrifluoroborates with sterically and electronically demanding aryl chlorides and bromides. The ensuing results represent the first comprehensive study of alkylboron coupling to aryl chlorides and, in particular, using secondary alkylboron partners. A ligand-dependent β-hydride elimination/reinsertion mechanism was implicated in the cross-coupling of more hindered substrates, leading to isomeric mixtures of coupled products in some cases. Copyright
- Dreher, Spencer D.,Dormer, Peter G.,Sandrock, Deidre L.,Molander, Gary A.
-
supporting information; body text
p. 9257 - 9259
(2009/02/02)
-
- A new class of nifuroxazide analogues: Synthesis of 5-nitrothiophene derivatives with antimicrobial activity against multidrug-resistant Staphylococcus aureus
-
Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) has been an increasing problem worldwide since the initial reports over 40 years ago. To examine new drug leads with potential antibacterial activities, 14 p-substituted benzoic acid [(5-nitro-thiophen-2-yl)-methylene]-hydrazides were designed, synthesized, and tested against standard and multidrug-resistant S. aureus strains by serial dilution tests. All compounds exhibited significant bacteriostatic activity and some of them also showed bactericidal activity. The results confirmed the potential of this class of compounds as an alternative for the development of selective antimicrobial agents.
- Masunari, Andrea,Tavares, Leoberto Costa
-
p. 4229 - 4236
(2008/03/13)
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- One Pot Electrooxidative Conversion of Benzyl Type Alcohols into the Corresponding Methyl Carboxylates
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One-pot conversion of several benzyl type alcohols into the corresponding methyl carboxylates was carried out by indirect electrooxidation using iodide ion as the electron carrier.
- Okimoto, Mitsuhiro,Nagata, Yuji,Sueda, Satoru,Takahashi, Yukio
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p. 281 - 285
(2007/10/03)
-
- Iron catalyzed cross coupling reactions of aromatic compounds
-
A process for the production of compounds Ar—R1 by means of a cross-coupling reaction of an organometallic reagent R1—M with an aromatic or heteroaromatic substrate Ar—X catalyzed by one or several iron salts or iron complexes as catalysts or pre-catalysts, present homogeneously or heterogeneously in the reaction mixture. This new invention exhibits substantial advantages over established cross coupling methodology using palladium- or nickel complexes as the catalysts. Most notable aspects are the fact that (i) expensive and/or toxic nobel metal catalysts are replaced by cheap, stable, commercially available and toxicologically benign iron salts or iron complexes as the catalysts or pre-catalysts, (ii) commercially attractive aryl chlorides as well as various aryl sulfonates can be used as starting materials, (iii) the reaction can be performed under “ligand-free” conditons, and (iv) the reaction times are usually very short.
- -
-
Page/Page column 5
(2010/02/03)
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- Iron-catalyzed cross-coupling reactions of alkyl-Grignard reagents with aryl chlorides, tosylates, and triflates
-
Aryl chlorides are better substrates than the corresponding bromides or iodides in the presented cross-coupling with alkyl Grignard reagents that is catalyzed by iron salts (see scheme); even aryl tosylates are converted efficiently. This situation is att
- Fuerstner, Alois,Leitner, Andreas
-
p. 609 - 612
(2007/10/03)
-
- Iron-catalyzed cross-coupling reactions
-
Simple iron salts such as FeCln, Fe(acac)n (n = 2,3) or the salen complex 4 turned out to be highly efficient, cheap, toxicologically benign, and environmentally friendly precatalysts for a host of cross-coupling reactions of alkyl o
- Fuerstner, Alois,Leitner, Andreas,Mendez, Maria,Krause, Helga
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p. 13856 - 13863
(2007/10/03)
-
- Antitumor Activity of 5-Aryl-2,3-dihydroimidazoisoquinolines
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A series of 5-aryl-2,3-dihydroimidazoisoquinolines previously reported to be platelet activating factor (PAF) receptor antagonist were evaluated for potential antitumor activity.Several compounds, such as the 5-(4'-tert-butylphenyl) (65), 5- (69), and 5-(4'-cyclohexylphenyl) (71) analogs showed very good cytotoxicity against several tumor cell lines. 5--2,3-dihydroimidazoisoquinoline (SDZ 62-434, 53) was more effective on a milligram per kilogram basis than the clinical cytostatic agent edelfosine (1) in increasing survivors and decreasing tumor volume in the oral mouse Meth A fibrosarcoma assay.It was selected for further development and is currently in phase I clinical trials in cancer patients.
- Houlihan, William J.,Munder, Paul G.,Handley, Dean A.,Cheon, Seung H.,Parrino, Vincent A.
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p. 234 - 240
(2007/10/02)
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- N2S2 tetradentate ligands for soft cationic species: preparation of new ligands of potential interest in nuclear medicine
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The synthesis of N2S2 tetradentate ligands of the bis-(enaminothioester) type was carried out starting from 3-(methylthio)-3H-1,2-dithiolylium iodides and diamines.The title compounds, which are potential ligands for soft cationic species, can be obtained from 1,3-diaminopropan-2-ol and subsequently modified into the dissymmetrical succinic acid ester of the ligand and N-hydroxysuccinimide.The appendage of such a linking group on the chelating structure should allow further grafting to monoclonal antibodies in view of potential applications in nuclear medicine. 3H-1,2-dithiole-3-thione / 1,3-diaminopropan-2-ol / bis-(enaminothioester) / N2S2 tetradentate ligand / N-hydroxysuccinimidyl ester
- Charbonnel-Jobic, Gaelle,Guemas, Jean-Pierre,Adelaere, Bruno,Parrain, Jean-Luc,Quintard, Jean-Paul
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p. 624 - 636
(2007/10/02)
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- Electrochemical Reduction of Organic Compounds. 22. Preparation of Aromatic Aldehydes by Electroreduction of Esters and Amides in the Presence of Chlorotrimethylsilane
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The electroreduction of aromatic esters 1 and amides 9 in dry acetonitrile in the presence of chlorotrimethylsilane 2 affords aldehydes 3 in moderate to good yields depending on the aromatic substituents.The formation of 3 and characteristic by-products is discussed.
- Goetz-Schatowitz, P.-R.,Struth, G.,Voss, J.,Wiegand, G.
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p. 230 - 234
(2007/10/02)
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- THERMAL CONVERSION OF METHYL 8-VINYL-3-OXO-2-OXABICYCLOOCT-5-EN-6-CARBOXYLATES TO TETRAHYDROCOUMARINS AND METHYL BENZOATES
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Methyl 8-methyl- and 8-methoxy-8-vinyl-3-oxo-2-oxabicyclooct-5-en-6-carboxylates (3 and 5), prepared by the Diels-Alder reaction of methyl 2-oxo-2H-pyran-5-carboxylate with 2-methyl- and 2-methoxy-1,3-butadienes, were converted into methyl 9-methyl- and 9-methoxy-3-oxo-2-oxabicyclodeca-4,8-diene-6-carboxylates (tetrahydrocoumarins) by a Cope rearrangement at about 140 deg C, respectively.On the other hand, 3 and 5 were transformed into methyl 4-isopropyl- and 4-acetylbenzoates via the reaction of methyl tricyclo2,7>oct-3-en-4-carboxylates at about 257 deg C in the presence of Pd-C, respectively.
- Matsui, Takanao,Matsushita, Yoh-ichi,Nakayama, Mitsuru
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p. 723 - 728
(2007/10/02)
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- Substituent effects on benzyl radical hyperfine coupling (hfc) constants. Part 3. Comparison of the α-hfc for substituted benzyl radicals with the β-hfc for substituted cumyl radicals
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The electron spin resonance (esr) spectra of eighteen para-substituted cumyl radicals were analyzed.The relationship between the β-hyperfine coupling (β-hfc) constants of these cumyl radicals and the corresponding α-hfc constants of benzyl radicals was studied.Although there is a general trend for the α- and β-hfc values to vary in a similar manner, specific deviations from a linear correlation between these parameters were observed.These deviations were rationalized by considering charge effects on spin delocalization.The correlation coefficient for the linear regression analysis of these α- and β-hfc values was found to significantly improve when parameters reflecting charge effects on spin delocalization were included in an extended Hammett treatment of the spectral data.
- Arnold, Donald R.,Nicholas, A. Martin de P.,Snow, Miles S.
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p. 1150 - 1156
(2007/10/02)
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- U.V. Absorbing cosmetic compositions
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Cosmetic compositions containing dibenzoylmethane compounds of the formula STR1 wherein R and R1 are straight-chain or branched alkyl of 1-8 carbon atoms, n an integer from 0-3 and n' an integer from 1-3, dissolved in the fatty components of said composition have superior sun-protection efficiency.
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- SYNTHESIS AND REARRANGEMENTS OF ALKYL-QUADRICYCLANONES
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Both 1-isopropyl-6- and 7-methoxycarbonyl-quadricyclanones, the first alkyl-substituted molecules of this type, have been synthesized.Cycloaddition reactions with methylpropiolate failed.Their different behaviour in rearrangement and degradation reactions
- Figeys, H. P.,Destrebecq, M.,Lommen, G. Van
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p. 2369 - 2372
(2007/10/02)
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