Oxidative 1,2-Difunctionalization of Ethylene via Gold-Catalyzed Oxyarylation

Oxidative 1,2-Difunctionalization of Ethylene via Gold-Catalyzed Oxyarylation
Matthew J. Harper†, Edward J. Emmett, John F. Bower , and Christopher A. Russell

School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
Syngenta, Jealott’s Hill International Research Centre, Bracknell, Berkshire RG42 6EY, United Kingdom

Link:J. Am. Chem. Soc., 2017, 139 (36), pp 12386–12389

DOI: 10.1021/jacs.7b06668
Publication Date (Web): August 22, 2017



Abstract



Under the conditions of oxidative gold catalysis, exposure of ethylene to aryl silanes and alcohols generates products of 1,2-oxyarylation. This provides a rare example of a process that allows catalytic differential 1,2-difunctionalization of this feedstock chemical.

A unified photoredox-catalysis strategy for C(sp3)– H hydroxylation and amidation using hypervalent iodine

A unified photoredox-catalysis strategy for C(sp3)– H hydroxylation and amidation using hypervalent iodine 

Guo-Xing Li,a Cristian A. Morales-Rivera,b Fang Gao,a Yaxin Wang,a Gang He,a Peng Liu *b and Gong Chen *ac

 

aState Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin 300071, China. E-mail: gongchen@nankai.edu. cn
bDepartment of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA. E-mail: pengliu@pitt.edu
cDepartment of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, PA 16802, USA. E-mail: guc11@psu.edu

Chem. Sci. 2017, ASAP 

DOI: 10.1039/c7sc02773g

http://pubs.rsc.org/en/content/articlepdf/2017/sc/c7sc02773g?page=search

Abstract:

We report a unified photoredox-catalysis strategy for both hydroxylation and amidation of tertiary and benzylic C–H bonds. Use of hydroxyl perfluorobenziodoxole (PFBl–OH) oxidant is critical for efficient tertiary C–H functionalization, likely due to the enhanced electrophilicity of the benziodoxole radical. Benzylic methylene C–H bonds can be hydroxylated or amidated using unmodified hydroxyl benziodoxole oxidant Bl–OH under similar conditions. An ionic mechanism involving nucleophilic trapping of a carbocation intermediate by H2O or CH3CN cosolvent is presented.

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Volume 23, Issue 50
September 7, 2017
Pages 11992–12003

Special Issue: Special Issue Celebrating the 150th Anniversary of the Gesellschaft Deutscher Chemiker (German Chemical Society)

Concept

Catalytic NH₃ Synthesis using N₂/H₂ at Molecular Transition Metal Complexes: Concepts for Lead Structure Determination using Computational Chemistry

Authors

Dr. Markus Hölscher^* and Prof. Dr. Walter Leitner

DOI: 10.1002/chem.201604612

 http://onlinelibrary.wiley.com/wol1/doi/10.1002/chem.201604612/abstract

Abstract

While industrial NH₃ synthesis based on the Haber–Bosch-process was invented more than a century ago, there is still no molecular catalyst available which reduces N₂ in the reaction system N₂/H₂ to NH₃. As the many efforts of experimentally working research groups to develop a molecular catalyst for NH₃ synthesis from N₂/H₂ have led to a variety of stoichiometric reductions it seems justified to undertake the attempt of systematizing the various approaches of how the N₂ molecule might be reduced to NH₃ with H₂ at a transition metal complex. In this contribution therefore a variety of intuition-based concepts are presented with the intention to show how the problem can be approached. While no claim for completeness is made, these concepts intend to generate a working plan for future research. Beyond this, it is suggested that these concepts should be evaluated with regard to experimental feasibility by checking barrier heights of single reaction steps and also by computation of whole catalytic cycles employing density functional theory (DFT) calculations. This serves as a tool which extends the empirically driven search process and expands it by computed insights which can be used to rationalize the various challenges which must be met.

Aqueous Au-Pd colloids catalyze selective CH4 oxidation to CH3OH with O2 under mild conditions

Aqueous Au-Pd colloids catalyze selective CH₄ oxidation to CH₃OH with O₂ under mild conditions

Nishtha Agarwal¹,Simon J. Freakley¹,Rebecca U. McVicker¹,Sultan M. Althahban²,Nikolaos Dimitratos¹,Qian He¹,David J. Morgan¹,Robert L. Jenkins¹David J. Willock¹,Stuart H. Taylor¹,Christopher J. Kiely¹,²Graham J. Hutchings¹,

1Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK.²Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015, USA.

http://science.sciencemag.org/content/early/2017/09/06/science.aan6515

Abstract

The selective oxidation of methane, the primary component of natural gas, remains an important challenge in catalysis. Using colloidal gold-palladium nanoparticles rather than the same nanoparticles supported on titanium oxide, we oxidized methane to methanol with high selectivity (92%) in aqueous solution at mild temperatures. Using isotopically labeled O₂ as an oxidant in the presence of H₂O_2, we demonstrate that the methanol produced incorporated a substantial fraction (70%) of gas-phase O₂. More oxygenated products were formed than H₂O₂ consumed, suggesting that the controlled breakdown of H₂O₂ activates methane which subsequently incorporates molecular oxygen through a radical process. If a source of methyl radicals can be established, then the selective oxidation of methane to methanol using molecular oxygen is possible.