Computational Studies of Carboxylate-Assisted C − H Activation and Functionalization at Group 8 − 10 Transition Metal Centers

Computational Studies of Carboxylate-Assisted C−H Activation and Functionalization at Group 8−10 Transition Metal Centers

 

Davies, D. L.; Macgregor, S. A.; McMullin, C. L. Chem. Rev. ASAP

 

University of Leicester & Heriot-Watt University

http://pubs.acs.org/doi/pdf/10.1021/acs.chemrev.6b00839

Abstract:

 

Computational studies on carboxylate-assisted C−H activation and functionalization at group 8−10 transition metal centers are reviewed. This Review is organized by metal and will cover work published from late 2009 until mid-2016. A brief overview of computational work prior to 2010 is also provided, and this outlines the understanding of carboxylate-assisted C−H activation in terms of the “ambiphilic metal−ligand assistance” (AMLA) and “concerted metalation deprotonation” (CMD) concepts. Computational studies are then surveyed in terms of the nature of the C−H bond being
activated (C(sp2)−H or C(sp3)−H), the nature of the process involved (intramolecular with a directing group or intermolecular), and the context (stoichiometric C−H activation or within a variety of catalytic processes). This Review aims to emphasize the connection between computation and experiment and to highlight the contribution of computational chemistry to our understanding of catalytic C−H functionalization based on carboxylate-
assisted C−H activation. Some opportunities where the interplay between computation and experiment may contribute further to the areas of catalytic C−H functionalization and applied computational chemistry are identified.

 

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Dehydrogenative Synthesis of Linear α,β-Unsaturated Aldehydes with Oxygen at Room Temperature Enabled by tBuONO

Mei-Mei Wang, Xiao-Shan Ning, Jian-Ping Qu, and Yan-Biao Kang*
Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China

ACS Catal., 2017, 7, pp 4000–4003

DOI: 10.1021/acscatal.7b01008

Synthesis of linear α,β-unsaturated aldehydes via a room-temperature oxidative dehydrogenation has been realized by the cocatalysis of an organic nitrite and palladium with molecular oxygen as the sole clean oxidant. Linear α,β-unsaturated aldehydes could be efficiently prepared under aerobic catalytic conditions directly from the corresponding saturated linear aldehydes. Besides linear products, the aromatic analogy could also be smoothly achieved by the same standard method. The organic nitrite redox cocatalyst and alcohol solvent play a key role for realizing this method.

β-Hydride Elimination and C–H Activation by an Iridium Acetate Complex, Catalyzed by Lewis Acids. Alkane Dehydrogenation Cocatalyzed by Lewis Acids and [2,6-Bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl]iridium

http://pubs.acs.org/doi/abs/10.1021/jacs.6b12995

Yang Gao, Changjian Guan, Meng Zhou, Akshai Kumar, Thomas J. Emge, Ashley M. Wright, Karen I. Goldberg, Karsten Krogh-Jespersen, and Alan S. Goldman*

J. Am. Chem. Soc., 2017, 139 (18), pp 6338–6350

ABSTRACT：

NaBArF4 (sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate) was found to catalyze reactions of (Phebox)IrIII(acetate) (Phebox = 2,6-bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) complexes, including (i) β-H elimination of (Phebox)Ir(OAc)(n-alkyl) to give (Phebox)Ir(OAc)(H) and the microscopic reverse, alkene insertion into the Ir–H bond of (Phebox)Ir(OAc)(H), and (ii) hydrogenolysis of the Ir–alkyl bond of (Phebox)Ir(OAc)(n-alkyl) and the microscopic reverse, C–H activation by (Phebox)Ir(OAc)(H), as indicated by H/D exchange experiments. For example, β-H elimination of (Phebox)Ir(OAc)(n-octyl) (2-Oc) proceeded on a time scale of minutes at −15 °C in the presence of (0.4 mM) NaBArF4 as compared with a very slow reaction at 125 °C in the absence of NaBArF4. In addition to NaBArF4, other Lewis acids are also effective. Density functional theory calculations capture the effect of the Na+ cation and indicate that it operates primarily by promoting κ2–κ1 dechelation of the acetate anion, which opens the coordination site needed to allow the observed reaction to proceed. In accord with the effect on these individual stoichiometric reactions, NaBArF4 was also found to cocatalyze, with (Phebox)Ir(OAc)(H), the acceptorless dehydrogenation of n-dodecane.

Copper Acetate for Catalytic Methane to MeTFA

http://onlinelibrary.wiley.com/doi/10.1002/1099-0739(200008)14:8%3C438::AID-AOC20%3E3.0.CO;2-L/full

 Cu(OAc)₂-catalyzed partial oxidation of methane to methyl trifluoroacetate in the liquid phase

Authors

• First published: 24 July 2000
• DOI: 10.1002/1099-0739(200008)14
• Cited by (CrossRef): 15 articles

Abstract

Simple transition-metal salts were investigated as the catalysts for the partial oxidation of methane. In trifluoroacetic acid (TFA), methane could be efficiently converted to methyl trifluoroacetate by the Cu(OAc)₂/K₂S₂O₈ catalyst system. A quantitative yield (96.3%) based on methane has been obtained under the optimized conditions. A possible mechanism involving radical intermediates has been suggested for this reaction. Copyright © 2000 John Wiley & Sons, Ltd.

Homogeneous Functionalization of Methane

Homogeneous Functionalization of Methane

Gunsalus, N. J.; Koppaka, A.; Park, S. H.; Bischof, S. M.; Hashiguchi, B. G.; Periana, R. A.*
The Scripps Research Institute

Chem. Rev. ASAP
http://pubs.acs.org/doi/pdf/10.1021/acs.chemrev.6b00739

Abstract:

One of the remaining “grand challenges” in chemistry is the development of a next generation, less expensive, cleaner process that can allow the vast reserves of methane from natural gas to augment or replace oil as the source of fuels and chemicals. Homogeneous (gas/liquid) systems that convert methane to functionalized products with emphasis on reports after 1995 are reviewed. Gas/solid, bioinorganic, biological, and reaction systems that do not specifically involve methane functionalization are excluded. The various reports are grouped under the main element involved in the direct reactions with methane. Central to the review is classification of the various reports into 12 categories based on both practical considerations and the mechanisms of the elementary reactions with methane. Practical considerations are based on whether or not the system reported can directly or indirectly utilize O2 as the only net coreactant based only on thermodynamic potentials. Mechanistic classifications are based on whether the elementary reactions with methane proceed by chain or nonchain reactions and with stoichiometric reagents or catalytic species. The nonchain reactions are further classified as CH activation (CHA) or CH oxidation (CHO). The bases for these various classifications are defined. In particular, CHA reactions are defined as elementary reactions with methane that result in a discrete methyl intermediate where the formal oxidation state (FOS) on the carbon remains unchanged at −IV relative to that in methane. In contrast, CHO reactions are defined as elementary reactions with methane where the carbon atom of the product is oxidized and has a FOS less negative than −IV. This review reveals that the bulk of the work in the field is relatively evenly distributed across most of the various areas classified. However, a few areas are only marginally examined, or not examined at all. This review also shows that, while significant scientific progress has been made, greater advances, particularly in developing systems that can utilize O2, will be required to develop a practical process that can replace the current energy and capital intensive natural gas conversion process. We believe that this classification scheme will provide the reader with a rapid way to identify systems of interest while providing a deeper appreciation and understanding, both practical and fundamental, of the extensive literature on methane functionalization. The hope is that this could accelerate progress toward meeting this “grand challenge.”

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