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14 Mar 08:43

[ASAP] Thermal, Catalytic Conversion of Alkanes to Linear Aldehydes and Linear Amines

by Xinxin Tang, Xiangqing Jia and Zheng Huang

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Journal of the American Chemical Society
DOI: 10.1021/jacs.8b01526
09 Mar 10:02

Ligand-Controlled Chemoselective C(acyl)–O Bond vs C(aryl)–C Bond Activation of Aromatic Esters in Nickel Catalyzed C(sp2)–C(sp3) Cross-Couplings

by Adisak Chatupheeraphat, Hsuan-Hung Liao, Watchara Srimontree, Lin Guo, Yury Minenkov, Albert Poater, Luigi Cavallo and Magnus Rueping

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Journal of the American Chemical Society
DOI: 10.1021/jacs.7b12865
31 Oct 14:40

MOF-derived cobalt nanoparticles catalyze a general synthesis of amines

by Jagadeesh, R. V., Murugesan, K., Alshammari, A. S., Neumann, H., Pohl, M.-M., Radnik, J., Beller, M.

The development of base metal catalysts for the synthesis of pharmaceutically relevant compounds remains an important goal of chemical research. Here, we report that cobalt nanoparticles encapsulated by a graphitic shell are broadly effective reductive amination catalysts. Their convenient and practical preparation entailed template assembly of cobalt-diamine-dicarboxylic acid metal organic frameworks on carbon and subsequent pyrolysis under inert atmosphere. The resulting stable and reusable catalysts were active for synthesis of primary, secondary, tertiary, and N-methylamines (more than 140 examples). The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, or nitro compounds, and molecular hydrogen under industrially viable and scalable conditions, offering cost-effective access to numerous amines, amino acid derivatives, and more complex drug targets.

03 Sep 21:38

Metal–Ligand Bifunctional Catalysis: The “Accepted” Mechanism, the Issue of Concertedness, and the Function of the Ligand in Catalytic Cycles Involving Hydrogen Atoms

by Pavel A. Dub and John C. Gordon

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ACS Catalysis
DOI: 10.1021/acscatal.7b01791
25 Aug 06:58

Nickel-Catalyzed Azide–Alkyne Cycloaddition To Access 1,5-Disubstituted 1,2,3-Triazoles in Air and Water

by Woo Gyum Kim, Mi Eun Kang, Jae Bin Lee, Min Ho Jeon, Sungmin Lee, Jungha Lee, Bongseo Choi, Pedro M. S. D. Cal, Sebyung Kang, Jung-Min Kee, Gonçalo J. L. Bernardes, Jan-Uwe Rohde, Wonyoung Choe and Sung You Hong

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Journal of the American Chemical Society
DOI: 10.1021/jacs.7b06338
31 Jul 07:40

Photocatalytic Conversion of Nitrogen to Ammonia with Water on Surface Oxygen Vacancies of Titanium Dioxide

by Hiroaki Hirakawa, Masaki Hashimoto, Yasuhiro Shiraishi and Takayuki Hirai

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Journal of the American Chemical Society
DOI: 10.1021/jacs.7b06634
10 Jul 14:54

Understanding the Unusual Reduction Mechanism of Pd(II) to Pd(I): Uncovering Hidden Species and Implications in Catalytic Cross-Coupling Reactions

by Carin C. C. Johansson Seechurn, Theresa Sperger, Thomas G. Scrase, Franziska Schoenebeck and Thomas J. Colacot

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Journal of the American Chemical Society
DOI: 10.1021/jacs.7b01110
10 Jul 14:54

Iron-Catalyzed C–H Bond Activation

by Rui Shang, Laurean Ilies and Eiichi Nakamura

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Chemical Reviews
DOI: 10.1021/acs.chemrev.6b00772
10 Jul 14:49

Remote carboxylation of halogenated aliphatic hydrocarbons with carbon dioxide

by Francisco Juliá-Hernández

Remote carboxylation of halogenated aliphatic hydrocarbons with carbon dioxide

Nature 545, 7652 (2017). doi:10.1038/nature22316

Authors: Francisco Juliá-Hernández, Toni Moragas, Josep Cornella & Ruben Martin

Catalytic carbon–carbon bond formation has enabled the streamlining of synthetic routes when assembling complex molecules. It is particularly important when incorporating saturated hydrocarbons, which are common motifs in petrochemicals and biologically relevant molecules. However, cross-coupling methods that involve alkyl electrophiles result in catalytic bond formation only at specific and previously functionalized sites. Here we describe a catalytic method that is capable of promoting carboxylation reactions at remote and unfunctionalized aliphatic sites with carbon dioxide at atmospheric pressure. The reaction occurs via selective migration of the catalyst along the hydrocarbon side-chain with excellent regio- and chemoselectivity, representing a remarkable reactivity relay when compared with classical cross-coupling reactions. Our results demonstrate that site-selectivity can be switched and controlled, enabling the functionalization of less-reactive positions in the presence of a priori more reactive ones. Furthermore, we show that raw materials obtained in bulk from petroleum processing, such as alkanes and unrefined mixtures of olefins, can be used as substrates. This offers an opportunity to integrate a catalytic platform en route to valuable fatty acids by transforming petroleum-derived feedstocks directly.

10 Jul 14:44

Palladium-catalyzed carbon-sulfur or carbon-phosphorus bond metathesis by reversible arylation

by Lian, Z., Bhawal, B. N., Yu, P., Morandi, B.

Compounds bearing aryl-sulfur and aryl-phosphorus bonds have found numerous applications in drug development, organic materials, polymer science, and homogeneous catalysis. We describe palladium-catalyzed metathesis reactions of both compound classes, each of which proceeds through a reversible arylation manifold. The synthetic power and immediate utility of this approach are demonstrated in several applications that would be challenging to achieve by means of traditional cross-coupling methods. The C(sp2)–S bond metathesis protocol was used in the depolymerization of a commercial thermoplastic polymer and in the late-stage derivatization of a drug. The C(sp2)–P variant led to the convenient preparation of a variety of phosphorus heterocycles, including a potential chiral ligand and fluorescent organic materials, via a ring-closing transformation.

10 Jul 14:44

Decarboxylative borylation

by Li, C., Wang, J., Barton, L. M., Yu, S., Tian, M., Peters, D. S., Kumar, M., Yu, A. W., Johnson, K. A., Chatterjee, A. K., Yan, M., Baran, P. S.

The widespread use of alkyl boronic acids and esters is frequently hampered by the challenges associated with their preparation. We describe a simple and practical method to rapidly access densely functionalized alkyl boronate esters from abundant carboxylic substituents. This broad-scope nickel-catalyzed reaction uses the same activating principle as amide bond formation to replace a carboxylic acid moiety with a boronate ester. Application to peptides allowed expedient preparations of α-amino boronic acids, often with high stereoselectivity, thereby facilitating synthesis of the alkyl boronic acid drugs Velcade and Ninlaro as well as a boronic acid version of the iconic antibiotic vancomycin. The reaction also enabled the discovery and extensive biological characterization of potent human neutrophil elastase inhibitors, which offer reversible covalent binding properties.

10 Jul 14:43

Simple and Efficient Generation of Aryl Radicals from Aryl Triflates: Synthesis of Aryl Boronates and Aryl Iodides at Room Temperature

by Wenbo Liu, Xiaobo Yang, Yang Gao and Chao-Jun Li

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Journal of the American Chemical Society
DOI: 10.1021/jacs.7b03538
10 Jul 14:43

Recent Advances in Radical C–H Activation/Radical Cross-Coupling

by Hong Yi, Guoting Zhang, Huamin Wang, Zhiyuan Huang, Jue Wang, Atul K. Singh and Aiwen Lei

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Chemical Reviews
DOI: 10.1021/acs.chemrev.6b00620
10 Jul 14:41

The Suzuki–Miyaura Coupling of Nitroarenes

by M. Ramu Yadav, Masahiro Nagaoka, Myuto Kashihara, Rong-Lin Zhong, Takanori Miyazaki, Shigeyoshi Sakaki and Yoshiaki Nakao

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Journal of the American Chemical Society
DOI: 10.1021/jacs.7b03159
08 May 16:05

Deoxygenation of Ethers To Form Carbon–Carbon Bonds via Nickel Catalysis

by Zhi-Chao Cao and Zhang-Jie Shi

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Journal of the American Chemical Society
DOI: 10.1021/jacs.7b02326
10 Dec 14:58

Disulfide-Catalyzed Visible-Light-Mediated Oxidative Cleavage of C=C Bonds and Evidence of an Olefin–Disulfide Charge-Transfer Complex

by Yuchao Deng, Xiao-Jing Wei, Hui Wang, Yuhan Sun, Timothy Noël, Xiao Wang

Abstract

A photocatalytic method for the aerobic oxidative cleavage of C=C bonds has been developed. Electron-rich aromatic disulfides were employed as photocatalyst. Upon visible-light irradiation, typical mono- and multi-substituted aromatic olefins could be converted into ketones and aldehydes at ambient temperature. Experimental and computational studies suggest that a disulfide–olefin charge-transfer complex is possibly responsible for the unconventional dissociation of S−S bond under visible light.

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Mild and metal-free: A photocatalytic method for the aerobic oxidative cleavage of C=C bonds has been developed with electron-rich aromatic disulfides as photocatalyst. Upon visible-light irradiation, aromatic olefins were converted into ketones and aldehydes at ambient temperature. A disulfide–olefin charge-transfer complex is possibly responsible for the S−S bond dissociation.

20 Nov 21:18

[Research Article] A general catalytic β-C–H carbonylation of aliphatic amines to β-lactams

by Darren Willcox
Methods for the synthesis and functionalization of amines are intrinsically important to a variety of chemical applications. We present a general carbon-hydrogen bond activation process that combines readily available aliphatic amines and the feedstock gas carbon monoxide to form synthetically versatile value-added amide products. The operationally straightforward palladium-catalyzed process exploits a distinct reaction pathway, wherein a sterically hindered carboxylate ligand orchestrates an amine attack on a palladium anhydride to transform aliphatic amines into β-lactams. The reaction is successful with a wide range of secondary amines and can be used as a late-stage functionalization tactic to deliver advanced, highly functionalized amine products of utility for pharmaceutical research and other areas. Authors: Darren Willcox, Ben G. N. Chappell, Kirsten F. Hogg, Jonas Calleja, Adam P. Smalley, Matthew J. Gaunt
04 Nov 15:41

Chemistry: Meteorite makes good catalyst

Chemistry: Meteorite makes good catalyst

Nature 538, 7625 (2016). doi:10.1038/538293a

An iron-based mineral from a meteorite can catalyse a chemical reaction that splits water into oxygen and hydrogen, which can be used as fuel.Some naturally occurring metallic minerals are known to have catalytic activity. Kevin Sivula and his colleagues at the Swiss Federal Institute

04 Nov 15:41

Catalytic Conversion of Renewable Resources into Bulk and Fine Chemicals

by Johannes G. de Vries

Abstract

Several strategies can be chosen to convert renewable resources into chemicals. In this account, I exemplify the route that starts with so-called platform chemicals; these are relatively simple chemicals that can be produced in high yield, directly from renewable resources, either via fermentation or via chemical routes. They can be converted into the existing bulk chemicals in a very efficient manner using multistep catalytic conversions. Two examples are given of the conversion of sugars into nylon intermediates. 5-Hydroxymethylfurfural (HMF) can be prepared in good yield from fructose. Two hydrogenation steps convert HMF into 1,6-hexanediol. Oppenauer oxidation converts this product into caprolactone, which in the past, has been converted into caprolactam in a large-scale industrial process by reaction with ammonia. An even more interesting platform chemical is levulinic acid (LA), which can be obtained directly from lignocellulose in good yield by treatment with dilute sulfuric acid at 200°C. Hydrogenation converts LA into gamma-valerolactone, which is ring-opened and esterified in a gas-phase process to a mixture of isomeric methyl pentenoates in excellent selectivity. In a remarkable selective palladium-catalysed isomerising methoxycarbonylation, this mixture is converted in to dimethyl adipate, which is finally hydrolysed to adipic acid. Overall selectivities of both processes are extremely high. The conversion of lignin into chemicals is a much more complicated task in view of the complex nature of lignin. It was discovered that breakage of the most prevalent β-O-4 bond in lignin occurs not only via the well-documented C3 pathway, but also via a C2 pathway, leading to the formation of highly reactive phenylacetaldehydes. These compounds went largely unnoticed as they immediately recondense on lignin. We have now found that it is possible to prevent this by converting these aldehydes in a tandem reaction, as they are formed. For this purpose, we have used three different methods: acetalisation, hydrogenation, and decarbonylation. These reactions were first established in the tandem reactions of model compounds, but subsequently, we were able to show that this works equally well on organosolv lignin and even on lignocellulose.

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Catalysis is the key technology for the conversion of biomass-derived platform chemicals into existing bulk chemicals. Highly selective low-temperature conversions make these multistep routes more attractive than single-step fermentation or high-temperature gasification or pyrolysis routes. Development of high yielding conversion of lignin into chemicals is still needed to complete the biorefinery concept.

04 Nov 15:41

[Report] Formaldehyde stabilization facilitates lignin monomer production during biomass depolymerization

by Li Shuai
Practical, high-yield lignin depolymerization methods could greatly increase biorefinery productivity and profitability. However, development of these methods is limited by the presence of interunit carbon-carbon bonds within native lignin, and further by formation of such linkages during lignin extraction. We report that adding formaldehyde during biomass pretreatment produces a soluble lignin fraction that can be converted to guaiacyl and syringyl monomers at near theoretical yields during subsequent hydrogenolysis (47 mole % of Klason lignin for beech and 78 mole % for a high-syringyl transgenic poplar). These yields were three to seven times those obtained without formaldehyde, which prevented lignin condensation by forming 1,3-dioxane structures with lignin side-chain hydroxyl groups. By depolymerizing cellulose, hemicelluloses, and lignin separately, monomer yields were between 76 and 90 mole % for these three major biomass fractions. Authors: Li Shuai, Masoud Talebi Amiri, Ydna M. Questell-Santiago, Florent Héroguel, Yanding Li, Hoon Kim, Richard Meilan, Clint Chapple, John Ralph, Jeremy S. Luterbacher
04 Feb 16:27

Conversion of CO2 from Air into Methanol Using a Polyamine and a Homogeneous Ruthenium Catalyst

by Jotheeswari Kothandaraman, Alain Goeppert, Miklos Czaun, George A. Olah and G. K. Surya Prakash

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Journal of the American Chemical Society
DOI: 10.1021/jacs.5b12354
04 Feb 16:20

Conversion of alkanes to linear alkylsilanes using an iridium–iron-catalysed tandem dehydrogenation–isomerization–hydrosilylation

by Xiangqing Jia

Nature Chemistry 8, 157 (2016). doi:10.1038/nchem.2417

Authors: Xiangqing Jia & Zheng Huang

The selective conversion of abundant and inexpensive alkane feedstocks into value-added speciality chemicals is a significant and challenging goal, and methods for catalytically converting alkanes into useful linear alkylsilanes are unknown, to date. Now, a strategy combining alkane dehydrogenation with regioselective olefin isomerization–hydrosilylation to produce linear alkylsilanes is described.

20 Oct 14:10

Sulfur-Limonene Polysulfide: A Material Synthesized Entirely from Industrial By-Products and Its Use in Removing Toxic Metals from Water and Soil

by Michael P. Crockett, Austin M. Evans, Max J. H. Worthington, Inês S. Albuquerque, Ashley D. Slattery, Christopher T. Gibson, Jonathan A. Campbell, David A. Lewis, Gonçalo J. L. Bernardes, Justin M. Chalker

Abstract

A polysulfide material was synthesized by the direct reaction of sulfur and D-limonene, by-products of the petroleum and citrus industries, respectively. The resulting material was processed into functional coatings or molded into solid devices for the removal of palladium and mercury salts from water and soil. The binding of mercury(II) to the sulfur-limonene polysulfide resulted in a color change. These properties motivate application in next-generation environmental remediation and mercury sensing.

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Waste not: A polysulfide has been synthesized from the industrial by-products sulfur and limonene. The material can be processed into coatings or molded into objects and responds selectively to mercury(II), producing a bright yellow deposit that adheres to the material (see picture). The use of the polysulfide in water and soil remediation is demonstrated.

02 Oct 13:34

Chemoselective Alkene Hydrosilylation Catalyzed by Nickel Pincer Complexes

by Ivan Buslov, Jeanne Becouse, Simona Mazza, Mickael Montandon-Clerc, Xile Hu

Abstract

Chemoselective hydrosilylation of functionalized alkenes is difficult to achieve using base-metal catalysts. Reported herein is that well-defined bis(amino)amide nickel pincer complexes are efficient catalysts for anti-Markovnikov hydrosilylation of terminal alkenes with turnover frequencies of up to 83 000 per hour and turnover numbers of up to 10 000. Alkenes containing amino, ester, amido, ketone, and formyl groups are selectively hydrosilylated. A slight modification of reaction conditions allows tandem isomerization/hydrosilylation reactions of internal alkenes using these nickel catalysts.

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High turnover: Well-defined bis(amino)amide nickel pincer complexes are efficient catalysts for anti-Markovnikov hydrosilylation of terminal alkenes. The turnover frequencies are up to 83 000 per hour and turnover numbers are up to 10 000. The C[DOUBLE BOND]C bonds of alkenes containing amino, ester, amido, ketone, and formyl groups are selectively hydrosilylated.

09 Sep 08:51

Nanonickel-Catalyzed Suzuki–Miyaura Cross-Couplings in Water

by Sachin Handa, Eric D. Slack, Bruce H. Lipshutz

Abstract

Nickel nanoparticles, formed in situ and used in combination with micellar catalysis, catalyze Suzuki–Miyaura cross-couplings in water under very mild reaction conditions.

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Under water: Nickel nanoparticles, formed in situ and used in combination with micellar catalysis, catalyze Suzuki–Miyaura cross-couplings in water under very mild reaction conditions. A wide range of substrates is tolerated and the reaction medium can be recycled.

09 Sep 08:50

[Report] Iron-catalyzed intermolecular [2+2] cycloadditions of unactivated alkenes

by Jordan M. Hoyt
Cycloadditions, such as the [4+2] Diels-Alder reaction to form six-membered rings, are among the most powerful and widely used methods in synthetic chemistry. The analogous [2+2] alkene cycloaddition to synthesize cyclobutanes is kinetically accessible by photochemical methods, but the substrate scope and functional group tolerance are limited. Here, we report iron-catalyzed intermolecular [2+2] cycloaddition of unactivated alkenes and cross cycloaddition of alkenes and dienes as regio- and stereoselective routes to cyclobutanes. Through rational ligand design, development of this base metal–catalyzed method expands the chemical space accessible from abundant hydrocarbon feedstocks. Authors: Jordan M. Hoyt, Valerie A. Schmidt, Aaron M. Tondreau, Paul J. Chirik
09 Sep 08:50

The Triple-Bond Metathesis of Aryldiazonium Salts: A Prospect for Dinitrogen Cleavage

by Aaron D. Lackner, Alois Fürstner

Abstract

The {N2} unit of aryldiazonium salts undergoes unusually facile triple-bond metathesis on treatment with molybdenum or tungsten alkylidyne ate complexes endowed with triphenylsilanolate ligands. The reaction transforms the alkylidyne unit into a nitrile and the aryldiazonium entity into an imido ligand on the metal center, as unambiguously confirmed by X-ray structure analysis of two representative examples. A tungsten nitride ate complex is shown to react analogously. Since the bonding situation of an aryldiazonium salt is similar to that of metal complexes with end-on-bound dinitrogen, in which {N2}[RIGHTWARDS ARROW]M σ donation is dominant and electron back donation minimal, the metathesis described herein is thought to be a conceptually novel strategy toward dinitrogen cleavage devoid of any redox steps and, therefore, orthogonal to the established methods.

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Who knows? Although the extrusion of molecular nitrogen from aryldiazonium salts is extremely facile, the metathetic cleavage of the N[BOND]N triple bond on treatment with alkylidyne ate complexes of molybdenum or tungsten is shown to be even faster. The analogy between [Ar-N2]+ and known [M-N2] complexes makes this process a potential model for dinitrogen cleavage devoid of any redox steps.

09 Sep 08:50

Nickel-Catalyzed Reductive Coupling of Aryl Bromides with Tertiary Alkyl Halides

by Xuan Wang, Shulin Wang, Weichao Xue and Hegui Gong

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Journal of the American Chemical Society
DOI: 10.1021/jacs.5b06255
09 Sep 08:50

CO2 Hydrogenation to Formate and Methanol as an Alternative to Photo- and Electrochemical CO2 Reduction

by Wan-Hui Wang, Yuichiro Himeda, James T. Muckerman, Gerald F. Manbeck and Etsuko Fujita

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Chemical Reviews
DOI: 10.1021/acs.chemrev.5b00197
09 Sep 08:49

Metal–Ligand Cooperation

by Julia R. Khusnutdinova, David Milstein

Abstract

Metal–ligand cooperation (MLC) has become an important concept in catalysis by transition metal complexes both in synthetic and biological systems. MLC implies that both the metal and the ligand are directly involved in bond activation processes, by contrast to “classical” transition metal catalysis where the ligand (e.g. phosphine) acts as a spectator, while all key transformations occur at the metal center. In this Review, we will discuss examples of MLC in which 1) both the metal and the ligand are chemically modified during bond activation and 2) bond activation results in immediate changes in the 1st coordination sphere involving the cooperating ligand, even if the reactive center at the ligand is not directly bound to the metal (e.g. via tautomerization). The role of MLC in enabling effective catalysis as well as in catalyst deactivation reactions will be discussed.

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Together we’re effective: Metal–ligand cooperation (MLC) implies that both the metal and the ligand are directly involved in bond activation processes, in contrast to “classical” transition metal catalysis where the ligand acts as a spectator, while all key transformations occur at the metal center. This Review discusses diverse modes of MLC in bond formation and bond cleavage reactions.