pinecone/core-2020-05-10-deduplication huggingface dataset:
An Improved Synthesis of BrettPhos- and RockPhos-Type Biarylphosphine Ligands

Improved processes for the preparation of biphenyl-based phosphine ligands t-BuBrettPhos, RockPhos, and BrettPhos are presented. The new methods, featuring the use of Grignard reagents and catalytic amounts of copper, are superior to the previous methods, which require the use of tert-butyllithium and stoichiometric amounts of copper. Specifically, the use of less dangerous reagents provides a safer process, while the use of catalytic amounts of copper allows for the isolation of pure products in high yield. These improvements are particularly significant for the large-scale preparation of these ligands.National Institutes of Health (U.S.) (GM46059)Astellas USA Foundatio
Microwave-Promoted Copper-Free Sonogashira–Hagihara Couplings of Aryl Imidazolylsulfonates in Water

Aryl imidazol-1-ylsulfonates have been efficiently cross-coupled with aryl-, alkyl-, and silylacetylenes in neat water under copper-free conditions at 110 °C assisted by microwave irradiation. Using 0.5 mol% of an oxime palladacycle as precatalyst, 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (SPhos, 2 mol%) as ligand, hexadecyltrimethylammonium bromide (CTAB) as additive, and triethylamine (TEA) as base, a wide array of disubstituted alkynes has been prepared in good to high yields in only 30 min.Financial support from the MICINN (Projects CTQ2007-62771/BQU, CTQ2010-20387 and Consolider INGENIO 2010 CSD2007-00006), FEDER, from the Generalitat Valenciana (Project PROMETEO/2009/038), and the University of Alicante is acknowledged
Enantioselective Synthesis of Cyclopentadienes by Gold(I)- Catalyzed Cyclization of 1,3-Dien-5-ynes

An asymmetric synthesis of elusive chiral cyclopentadienes has been developed by gold(I)-catalyzed alkoxycyclization of 1,3-dien-5-ynes. The application of these substrates in completely diastereoselective Diels–Alder cycloaddition reactions, which can be carried out in one pot from achiral 1,3-dien-5-ynes, allows the preparation of highly functionalized products bearing five stereogenic centers with high enantiomeric excessesMinisterio de Ciencia e Innovacion (MICINN) and FEDER (CTQ2010-15358 and CTQ2009-09949/BQU) and Junta de Castilla y Leon (BU021A09 and GR-172) for financial support. A. M. S. thanks Junta de Castilla y Leon (Consejeria de Educacion) and Fondo Social Europeo for a PIRTU contract. P. G.-G. and M. A. F.-R. thank MICINN for "Juan de la Cierva" and "Ramon y Cajal" contractsThis is the peer reviewed version of the following article: Sanjuán, A. M., García-García, P., Fernández-Rodríguez, M. A. and Sanz, R. (2013), Enantioselective Synthesis of Cyclopentadienes by Gold(I)- Catalyzed Cyclization of 1,3-Dien-5-ynes. Adv. Synth. Catal., 355: 1955–1962. doi: 10.1002/adsc.201300448, which has been published in final form at 10.1002/adsc.201300448. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archivin
Development of chiral phosphoric acids based on ferrocene-bridged paracyclophane frameworks

International audienceThis work deals with the development of a new family of planar chiral phosphoric acids, based on a ferrocenophane/paracyclophane scaffold. The synthetic approach has been improved by taking advantage of a chiral phosphorylating agent to access enantiomerically enriched acids via diastereomers separation. These phosphoric acids have been used as catalysts for the enantioselective H-transfer reduction of alpha-substituted quinolines with Hantzsch esters. Optimization of both the catalyst and the Hantzsch reductant allowed ee in the range 82-92% to be attained starting from alpha-arylquinolines
Gold versus Palladium: A Regioselective Cycloisomerization of Aromatic Enynes

International audienceAromatic enynes can be transformed into arylnaphthalenes or benzofulvenes depending on the reaction conditions. Under gold(I) catalysis, exclusive or major 6-endo-dig cyclization took place leading to arylnaphthalenes. However, a catalytic system based on palladium iodide/1,3-Bis(diphenylphosphino)propane, in the presence of cesium carbonate as a base was necessary to furnish exclusively 5-exo-dig cyclization pattern, regardless to the electronic effects of the substituents. In the latter transformation, a mechanistic study (Kinetic Isotopic Effect, Density Functional Theory) involving a C-H activation is suggested for the exclusive benzofulvenes formation
Brønsted Acid-Catalyzed Straightforward Synthesis of Benzo[b]carbazoles from 2,3-Unsubstituted Indoles

Described is a general and efficient synthesis of valuable benzo[b]carbazoles by Brønsted acid-catalyzed reactions between simple C-2,C-3-unsubstituted indoles and ortho-[α-(hydroxy)benzyl]benzaldehyde acetals. Highly selective migration processes are involved as key steps in the overall cascade sequence that involves the one-pot formation of two new bonds and a cycle in a regioselective fashion.Ministerio de Economia y Competitividad (MINECO) and FEDER (CTQ2010-15358) for financial suuport. P. G.-G. and M.A.F.-R. thank MINECO for "Juan de la Cierva" and "Ramon y Cajal" contractsThis is the peer reviewed version of the following article: Suárez, A., García-García, P., Fernández-Rodríguez, M. A. and Sanz, R. (2014), Brønsted Acid-Catalyzed Straightforward Synthesis of Benzo[b]carbazoles from 2,3-Unsubstituted Indoles. Adv. Synth. Catal., 356: 374–382. doi: 10.1002/adsc.201300868, which has been published in final form at 10.1002/adsc.201300868. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving
Palladium(0)-Catalyzed Carbon[BOND]Hydrogen Bond Functionalization for the Synthesis of Indoloquinazolinones

The indoloquinazolinone ring system has attracted considerable attention as a pharmacophore, because it shows various biological activities. The reported synthetic methods for the compound are simple and direct, but are not effective for the direct synthesis of indoloquinazolinone with a methylene group at the C-6 position. A palladium(0)-catalyzed cyclization of chloroquinazolinone via C H functionalization was developed for a concise synthesis of indoloquinazolinone derivatives. The presence of a substituent at the C-6 position is important for obtaining the product in good yield. The conformation of the reaction intermediate, in particular the N C Pd bond angle, is important for the regioselectivity of the reaction
Cobalt-Impregnated Magnetite as General Heterogeneous Catalyst for the Hydroacylation Reaction of Azodicarboxylates

Catalysts consisting of cobalt and nickel impregnated on magnetite have been prepared, characterized and used for the hydroacylation reaction of different azodicarboxylate compounds with aldehydes, using nearly stoichiometric amounts of both reagents in only 3 h. Furthermore, this reaction has been conducted with the smallest amount of catalyst. The cobalt catalyst is stable enough to be removed by magnetic decantation and recycled ten-fold without any detrimental effect on the results.This work was supported by the Spanish Ministerio de Economía y Competitividad (MICINN; CTQ2011-24151) and University of Alicante. J. M.P. thanks the MICINN (FPI program) for her fellowship
Selective Aryl alpha-Diimine/Palladium-Catalyzed Bis-Alkoxy- carbonylation of Olefins for the Synthesis of Substituted Succinic Diesters

Aryl alpha-diimine derivatives have been used, for the first time, as efficient new ligands for the palladium-catalyzed oxidative bis-alkoxycarbonylation reaction of olefins. The most active catalyst was formed in situ from bis(9-anthryl)-2,3-dimethyl-1,4-diazabutadiene and palladium(II) trifluoroacetate [Pd(TFA)2]. This catalytic system was able to selectively convert olefins into succinic diesters in good yields (up to 97%) and low catalyst loading (up to 0.5 mol%) under mild reaction conditions [4 bar of carbon monoxide (CO) at 20 °C in the presence of p-toluenesulphonic acid as additive and p-benzoquinone as oxidant]. The optimized conditions could be successfully applied to both aromatic and aliphatic olefins, by using methanol, benzyl alcohol or isopropyl alcoho
Efficient Diastereo- and Enantioselective Synthesis of exo-Nitroprolinates by 1,3-Dipolar Cycloadditions Catalyzed by Chiral Phosphoramidite⋅Silver(I) Complexes

Chiral complexes formed by privileged phosphoramidites and silver triflate or silver benzoate are excellent catalysts for the general 1,3-dipolar cycloaddition between azomethine ylides generated from α-amino acid-derived imino esters and nitroalkenes affording with high dr the exo-cycloadducts 4,5-trans-2,5-cis-4-nitroprolinates in high ee at room temperature. In general, better results are obtained using silver rather than copper(II) complexes. In many cases the exo-cycloadducts can be obtained in enantiomerically pure form just after simple recrystallization. The mechanism and the justification of the experimentally observed stereodiscrimination of the process are supported by DFT calculations. These enantiomerically enriched exo-nitroprolinates can be used as reagents for the synthesis of nitropiperidines, by ester reduction and ring expansion, which are inhibitors of farnesyltransferase.This work has been supported by the Spanish Ministerio de Ciencia e Innovación (MICINN) (Consolider INGENIO 2010 CSD2007-00006, CTQ2010-20387), FEDER, Generalitat Valenciana (PROMETEO/2009/039abd PROMETEOII/2014/017), and by the University of Alicante. L. M. C. thanks the MICINN for an FPI fellowship. Financial support was provided by the MICINN and FEDER (projects CTQ2010-16959/BQU, and Consolider-Ingenio CSD2007-00006), the University of the Basque Country (UPV/EHU, UFI11/22 QOSYC), the Basque Government (GV/EJ, grant IT-324-07). The authors thank the SGI/IZO-SGIker UPV/EHU and the DIPC for generous allocation of computational resources
The synthesis of highly active iridium(I) complexes and their application in catalytic hydrogen isotope exchange

A series of robust iridium(I) complexes bearing a sterically encumbered N-heterocyclic carbene ligand, alongside a phosphine ligand, has been synthesised and investigated in hydrogen isotope exchange processes. These complexes have allowed isotope incorporation over a range of substrates with the use of practically convenient deuterium and tritium gas. Moreover, these active catalysts are capable of isotope incorporation to particularly high levels, whilst employing low catalyst loadings and in short reaction times. In addition to this, these new catalyst species have shown flexible levels of chemoselectivity, which can be altered by simple manipulation of preparative approaches. Furthermore, a number of industrially-relevant drug molecules have also been labelled, including the sulfonamide containing drug, Celecoxib. Alongside detailed NMR experiments, initial mechanistic investigations have also been performed, providing insight into both substrate binding energies, and, more importantly, relative energies of key steps in the mechanistic cycle as part of the overall exchange process
Rhodium nanoflowers stabilized by a nitrogen-rich PEG-tagged substrate as recyclable catalyst for the stereoselective hydrosilylation of internal alkynes

Morphology and size controllable rhodium nanoparticles stabilized by a nitrogen-rich polyoxyethylenated derivative have been prepared by reduction of RhCl3 with NaBH4 in water at room temperature and fully characterized. The flower-like Rh NPs are effective and recyclable catalysts for the stereoselective hydrosilylation of challenging internal alkynes and diynes, affording the (E)-vinylsilanes in quantitative yields for a wide range of substrates. The insolubility of the nanocatalyst in diethyl ether allows its easy separation and recycling
Modular ligands for dirhodium complexes facilitate catalyst customization

Although stereoselectivity is often the focus of ligand optimizations in catalysis, ligand modularity can be used to control many other properties of catalysts. For example, solubility, amenability to purification, and steric shielding of sensitive catalytic intermediates are all important, but seldom appreciated, functions of ligands. We describe a brief and modular approach to various homo- and heteroleptic lantern-type rhodium(II) complexes and perform benchmarking studies with the new catalysts in common rhodium(II)-catalyzed reactions. We demonstrate the power of ligand modularity by creating catalysts customized for aqueous catalysis or for applications in chemical biology
Chemistry of pyruvate enolates : anti-selective direct aldol reactions of pyruvate ester with sugar aldehydes promoted by a dinuclear zinc catalyst

A chiral dinuclear zinc complex can effectively catalyse the direct aldol reactions of pyruvic acid ester with various chiral sugar aldehydes, thus functionally mimicking the pyruvate-dependent type II aldolases. Application of sterically hindered aryl esters allows for the elusive aldol reaction of the pyruvate donor with controlled anti-selectivity en route to the short and efficient synthesis of 3-deoxy-2-ulosonic acids. Pyruvic acid ester is here used as a chemical equivalent of phosphoenol pyruvate (PEP) in imitation of the synthetic principle used in nature. The presented biomimetic methodologies use enol formation for the highly efficient and flexible formation of various C6–C9 ulosonic acids. Particularly, efficient and concise syntheses of 3-deoxy-D-erythro-hex-2-ulosonic acid (KDG, overall 50% yield), 3-deoxy-D-ribo-hept-2-ulosonic acid (DRH, overall 53% yield) and 3-deoxy-D-glycero-D-talo-non-2-ulosonic acid (4-epi-KDN, overall 78% yield) are described. This direct efficient application of pyruvic esters does not require additional demasking steps and thus surpassess previously methodologies utilising masked pyruvic synthons such 2-acetylthiazole and pyruvic aldehyde dimethyl acetal
Understanding potentials and restrictions of solvent-free enzymatic polycondensation of itaconic acid: an experimental and computational analysis

Itaconic acid is a chemically versatile unsaturated diacid that can be produced by fermentation and potentially it can replace petrol based monomers such as maleic and fumaric acids in the production of curable polyesters or new biocompatible functionalized materials. Unfortunately, due to the presence of the unsaturated C=C bond, polycondensation of itaconic acid is hampered by cross reactivity and isomerization. Therefore, enzymatic polycondensations would respond to the need of mild and selective synthetic routes for the production of novel bio-based polymers. The present work analyses the feasibility of enzymatic polycondensation of diethyl itaconate and, for the first time, provides comprehensive solutions embracing both the formulation of the biocatalyst, the reaction conditions and the choice of the co-monomers. Computational docking was used to disclose the structural factors responsible for the low reactivity of dimethyl itaconate and to identify possible solutions. Surprisingly, experimental and computational analysis revealed that 1,4-butanediol is an unsuitable co-monomer for the polycondensation of dimethyl itaconate whereas the cyclic and rigid 1,4-cyclohexanedimethanol promotes the elongation of the oligomers
Expedient Iodocyclization Approach Toward Polysubstituted 3H-Benzo[e]indoles

A facile and expedient iodocyclization of 4-(2-prop-1-ynylphenyl)-1H-pyrroles towards the synthesis of polysubstituted 3H-benzo[e]indoles is reported. The transformation was optimized and the best results were obtained by using iodine (1.2 equiv,) in dichloromethane, and potassium carbonate as base. The starting 1,2,3,4-tetrasubstituted pyrroles were efficiently obtained by means of a nickel(II) chloride-promoted four-component (nitromethane, amine, 2-alkynylbenzaldehyde and ethyl acetoacetate) reaction. Further functionalization of the resulting 5-iodoheterocycles was also explored.Fil: Martins, Guilherme M.. Universidade Federal de Santa Maria. Departamento de Qu ímica; BrasilFil: Zeni, Gilson. Universidade Federal de Santa Maria. Departamento de Qu ímica; BrasilFil: Back, David F.. Universidade Federal de Santa Maria. Departamento de Qu ímica; BrasilFil: Kaufman, Teodoro Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Silveira, Claudio C.. Universidade Federal de Santa Maria. Departamento de Qu ímica; Brasi
Palladium-Catalyzed Remote ortho-C-H Alkenylation of Alkyl Aryl Sulfones: Access to Densely Functionalized Indane Derivatives

This is the peer-reviewed version of the following article: Advanced Synthesis and Catalysis 358.7 (2016): 1065-1072, which has been published in final form at http://dx.doi.org/10.1002/adsc.201501129. This article may be used for non-commercial purposes in accordance with Wiley-VCH Terms and Conditions for Self-ArchivingA practical method for the palladium-cat-alyzed ortho-olefination of benzyl and phenethyl 2-pyridyl sulfones with electron-deficient alkenes using N-fluoro-2,4,6-trimethylpyridinium triflate ([F+]) as the terminal oxidant is described. The che-lating auxiliary (2-pyridyl)sulfonyl unit was demon-strated to be the key to the success of this reaction, which occurs efficiently with excellent regioselectiv-ity and monosubstitution selectivity. A variety of steric and electronic changes to both coupling part-ners is tolerated, including substitution at the ben-zylic position of the sulfone compound. Further-more, no appreciable loss of enantiopurity is ob-served when using non-racemic substrates. This method provides access to indane derivatives hold-ing three contiguous stereogenic centers with high diastereocontrol. The indane framework was con-structed by intramolecular Michael addition of the a-sulfonyl carbanion to the electrophilic alkeneWe thank the Spanish Government (MINECO, CTQ2012- 35790) for financial support. P.D. L. thanks the Spanish Government (MINECO) for an FPU predoctoral fellowshi
Oxidative Alkoxycarbonylation of Alkynes by Means of Aryl α-Diimine Palladium(II) Complexes as Catalysts

The straightforward in situ synthesized Bis-(2,6-diisopropyl)-acenaphthenequinonediimine palladium triflate catalyst was generally employed for both the mono-alkoxycarbonylation of terminal alkynes, and the bis-alkoxycarbonylation of 1,2-disubstituted alkynes by using mild reaction conditions (PCO= 4 bar, Temp. 20°C). Utilizing low catalyst loading (down to 0.5 mol%), a variety of propiolic esters were synthesized with good to excellent isolated yields. Most importantly the system was very efficient not only with methanol but also with a range of different alcohols, starting from the less hindered benzyl alcohol to the most ones, such as isopropanol and tert-butanol. In addition aromatic and aliphatic 1,2-disubstituted alkynes were converted into maleic acid derivatives, together with acid-catalyzed isomerization reaction, showing modest to good selectivity and excellent combined yields. In particular 3-hexyne showed a satisfactory degree of selectivity for the maleic diesters of methanol, and benzyl alcohol, obtaining the corresponding products with good isolated yields
Short and Efficient Chemoenzymatic Syntheses of non-Natural (−)-Muscarine and (+)-allo-Muscarine from Cyano-Sugar Precursors Catalyzed by Immobilized Burkholderia cepacia Lipase

Enantiopure (2R)-configured non-natural (−)-muscarine and (+)-allo-muscarine were efficiently synthesized by a chemoenzymatic approach from an easily accessible cyano-sugar available on large-scale. The key enzymatic hydrolysis step was accomplished by immobilized Burkholderia cepacia lipase (also known as Pseudomonas cepacia lipase, PSL-IM). The PSL-IM mediated regioselective hydrolysis of the 5-O-toluoyl ester group in cyano-sugars α− and β−, furnished 3-O-toluoyl-α-cyano-sugar and 3-O-toluoyl-β-cyano-sugar, respectively, with total selectivity and in excellent yields. To demonstrate the industrial utility of this method, 3-O-toluoyl-β-cyano-sugar was synthesized on 10 g scale using PSL-IM and catalyst reused. A key feature of the synthesis route described herein is the simultaneous hydrogenolysis of a tosyl group, reduction of a nitrile and deprotection of a toluoyl group using LiAlH4 in one-pot procedure. This study offers green protocol for synthesis of two muscarine derivatives in high yields employing a concise four-step strategy
Molybdenum-catalyzed deoxygenation of heteroaromatic n-oxides and hydroxides using Pinacol as Reducing Agent

A molybdenum-catalyzed deoxygenationof pyridine N -oxides and N-hydroxybenzotriazoles,as well as other azole N-oxides, has been developedusing pinacol as an environmentally friendly oxo-acceptor. The only by-products are acetone andwater making the process a convenient alternativeto established protocols in terms of waste gener-ation. The reaction is highly chemose lective and avariety of functional groups are tolerated. Theprocesses are usually very clean allowing theisolation of the pure deoxygenated products after asimple extraction in most cases.Ministerio de Economı´ayCompetitividad (MINECO) (CTQ2013-48937-C2-1-P,CTQ2015-70371-REDT, and CTQ2016-75023-C2-1-P) andJunta de Castilla y Leo´n and FEDER (BU076U16)This is the peer reviewed version of the following article: R. Rubio-Presa, M. A. Fernández-Rodríguez, M. R. Pedrosa, F. J. Arnáiz, R. Sanz, Adv. Synth. Catal. 2017, 359, 1752. doi: 10.1002/adsc.201700071, which has been published in final form at 10.1002/adsc.201700071. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archivin
Combining Sanford arylations on benzodiazepines with the nuisance effect

5-Phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-ones react under palladium- and visible light photoredox catalysis, in refluxing methanol, with aryldiazonium salts to afford the respective 5-(2- arylphenyl) analogues. With 2- or 4-fluorobenzenediazonium derivatives, both fluoroaryl- and methoxyaryl- products were obtained, the latter resulting from a SNAr on the fluorobenzenediazonium salt (“nuisance effect”). A computational DFT analysis of the palladium-catalysed and the palladium/ruthenium-photocalysed mechanism for the functionalization of benzodiazepines indicated that in the presence of the photocatalyst the reaction proceeds via a low-energy SET pathway avoiding the high-energy oxidative addition step in the palladium-only catalysed reaction pathway
Tin soaps in emulsion PVC heat stabilization

In this study, the effect of a liquid stabilizer based on organotins on PVC heat stability is investigated. Control and films with tin soap heat stabilizer Sn500K were prepared by solvent casting and they were heated at 160 and 180°C for different time periods. X-ray fluorescence spectroscopy analysis showed that tin was present in Sn500K and it was lead-free. DSC analysis showed that glass-transition temperature of films with Sn500K increased from 67 to 75-85°C by heating for 15 min at 180°C. IR spectroscopy indicated that concentration of carboxylate groups of Sn500K decreased with heating. Films with Sn500K did not degrade for short heating periods; however, degradation occurred in long heating times. Low concentration of Sn500K was recommended, since at high levels incompatibility with PVC and acceleration of degradation was observed. In the high temperature range, control and stabilized samples degraded in the same manner in two step