Editorial pubs.acs.org/CR
Introduction: CH Activation he first glimmerings of advance in the homogeneous catalysis of C−H activation and functionalization reactions by transition metal complexes go right back to Fenton with his classic 1894 paper.1 The modern development of the topic, however, dates from the 1970s with Shilov’s platinum chemistry,2 on which Labinger has contributed a review in this issue.3 An early and continuing aspiration of C−H activation is the possibility of methane conversion to useful partial oxidation products such as MeOH. This need has only grown more intense with the rise of hydrofracking, a technique that has very greatly enhanced the global supply of methane. Schwach, Pan, and Xinhe Bao cover this area with their review of heterogeneous catalytic reactions.4 Periana and co-workers also cover this problem but from the homogeneous side with a mechanism-based discussion of the different approaches that either could be or are being adopted.5 A third approach, based on methane monooxygenases and their mimics, is discussed by Sunney Chan and co-workers.6 Physicochemical and theoretical studies help provide the fundamental basis on which the catalytic work can best be planned. Jin-Pei Cheng and co-workers discuss the relevant bond strength data and how they relate to reactivity and selectivity.7 On the other hand, Davies, Macgregor, and McMullin cover the computational aspects of carboxylateassisted C−H activation.8 Perutz and Eisenstein look at the competition between C−H and C−F bond activation in fluorocarbons.9 Palladium, the champion catalytic metal for coupling chemistry, is covered by Jin-Quan Yu and co-workers for the case of sp3 C−H activation.10 Palladium also plays a major role in the work on sp2 C−H activation reviewed by Jingsong You and co-workers that covers oxidative heteroarene−heteroarene coupling.11 A variety of metals and mechanisms are at play in the review by Weiping Su and co-workers on decarboxylative C−H functionalization, a reaction with high promise in the sense that a wide variety of carboxylic acids are readily available.12 The catalytic enantioselective transformations discussed in the review by Cramer and co-workers also rely heavily on Pd.13 Jun and co-workers cover precious metal− ligand cooperation to provide selectivity in C−H activation.14 Aiwen Lei covers radical C−H activation and radical crosscoupling.15 Moving to a cheaper metal may make economic sense if the catalytic activity permits. In this vein, Shang, Ilies, and Nakamura look at stoichiometric and catalytic C−H bond activation with iron.16 Collins and Ryabov cover the wellknown TAML iron-based catalysts that are extremely effective in a wide variety of oxidative processes.17 Ellman and coworkers cover a wide variety of metals, both precious and base, for catalyzed C−H bond addition to polar groups.18 A wide variety of metals catalyze acceptorless dehydrogenative alcohol oxidation, as discussed in Crabtree’s review,19 which also includes applications to heterocycle synthesis and hydrogen storage. Chang and co-workers cover catalyzed C−H
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© 2017 American Chemical Society
amination, again involving a variety of metals.20 C−H functionalization of azines is the topic of the review by Murakami, Itami, and co-workers.21 Guangbin Dong and coworkers look at CH alkylation with alkenes as the alkylating agent.22 Finally, C−C activation has gained attention, with the main reactivity being shown by strained ring systems, as discussed by Bower and co-workers.23 A new player in the CH activation field is organocatalysis, a field with green credentials by avoiding metals altogether. Qin, Zhu, and Sanzhong Luo discuss this aspect in the context of a variety of useful CH functionalizations.24 C−H activation and functionalization, once considered exotic exceptions to the general rules, has now become a key concept that cannot easily be ignored in the design of synthetic work. In particular, late stage functionalization25 of complex organic molecules provides a potential way to simplify synthetic strategies as well as permit a wider variety of final products to be made from the same late stage intermediate.
Robert H. Crabtree Yale University
Aiwen Lei
Wuhan University
AUTHOR INFORMATION ORCID
Robert H. Crabtree: 0000-0002-6639-8707 Aiwen Lei: 0000-0001-8417-3061 Notes
Views expressed in this editorial are those of the authors and not necessarily the views of the ACS. Biographies
Bob Crabtree, educated at New College, Oxford with Malcolm Green, did his Ph.D. with Joseph Chatt at Sussex and spent four years in Paris with Hugh Felkin at the CNRS, Gif. At Yale since 1977, he is now the Whitehead Professor. He has been an ACS and RSC organometallic Special Issue: CH Activation Published: July 12, 2017 8481
DOI: 10.1021/acs.chemrev.7b00307 Chem. Rev. 2017, 117, 8481−8482
Chemical Reviews
Editorial
(8) Davies, D. L.; Macgregor, S. A.; McMullin, C. L. Computational Studies of Carboxylate-Assisted C−H Activation and Functionalization at Group 8−10 Transition Metal Centers. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00839. (9) Eisenstein, O.; Milani, J.; Perutz, R. N. Selectivity of C−H activation and competition between C−H and C−F bond activation at fluorocarbons. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.7b00163. (10) He, J.; Wasa, M.; Chan, K. S. L.; Shao, Q.; Yu, J. Q. PalladiumCatalyzed Transformations of Alkyl C−H Bonds. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00622. (11) Yang, Y.; Lan, J.; You, J. Oxidative C−H/C−H Coupling Reactions between Two (Hetero)arenes. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00567. (12) Wei, Y.; Hu, P.; Zhang, M.; Su, W. Metal-Catalyzed Decarboxylative C−H Functionalization. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00516. (13) Newton, C. G.; Wang, S. G.; Oliveira, C. C.; Cramer, N. Catalytic Enantioselective Transformations Involving C−H Bond Cleavage by Transition-Metal Complexes. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00692. (14) Kim, D. S.; Park, W. J.; Jun, C. H. Metal−Organic Cooperative Catalysis in C−H and C−C Bond Activation. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00554. (15) Yi, H.; Zhang, G.; Wang, H.; Huang, Z.; Wang, J.; Singh, A. K.; Lei, A. Recent Advances in Radical C−H Activation/Radical CrossCoupling. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00620. (16) Shang, R.; Ilies, L.; Nakamura, E. Iron-Catalyzed C−H Bond Activation. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00772. (17) Collins, T. J.; Ryabov, A. D. Targeting of High-Valent IronTAML Activators at Hydrocarbons and Beyond. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.7b00034. (18) Hummel, J. R.; Boerth, J. A.; Ellman, J. A. Transition-MetalCatalyzed C−H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00661. (19) Crabtree, R. H. Homogeneous Transition Metal Catalysis of Acceptorless Dehydrogenative Alcohol Oxidation: Applications in Hydrogen Storage and to Heterocycle Synthesis. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00556. (20) Park, Y.; Kim, Y.; Chang, S. Transition Metal-Catalyzed C−H Amination: Scope, Mechanism, and Applications. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00644. (21) Murakami, K.; Yamada, S.; Kaneda, T.; Itami, K. C−H Functionalization of Azines. Chem. Rev. 2017, DOI: 10.1021/ acs.chemrev.7b00021. (22) Dong, Z.; Ren, Z.; Thompson, S. J.; Xu, Y.; Dong, G. Transition-Metal-Catalyzed C−H Alkylation Using Alkenes. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00574. (23) Fumagalli, G.; Stanton, S.; Bower, J. F. Recent Methodologies That Exploit C−C Single-Bond Cleavage of Strained Ring Systems by Transition Metal Complexes. Chem. Rev. 2017, DOI: 10.1021/ acs.chemrev.6b00599. (24) Qin, Y.; Zhu, L.; Luo, S. Organocatalysis in Inert C−H Bond Functionalization. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00657. (25) Chen, M. S.; White, M. C. A predictably selective aliphatic C-H oxidation reaction for complex molecule synthesis. Science 2007, 318, 783−787.
chemistry awardee, Baylor Medallist, Mond lecturer, Kosolapoff awardee, and Stauffer Lecturer, has chaired the ACS Inorganic Division, and is the author of an organometallic textbook, now in its 6th edition. Early work on catalytic alkane C−H activation and functionalization was followed by exploration of H2 complexation, dihydrogen bonding, and catalysis of water splitting. He is a Fellow of the ACS, RSC, IUPAC, and the American Academy as well as a member of the National Academy of Sciences.
Aiwen Lei obtained his doctoral degree in 2000 with Xiyan Lu at the Shanghai Institute of Organic Chemistry of the Chinese Academy of Science and then worked as a postdoctoral fellow with Xumu Zhang at Penn State (2000−2003) and James P. Collman at Stanford (2003− 2005). From 2005, he started his independent career at Wuhan University. He is a Chang Jiang Scholar and currently serves as an Associate Dean of the Institute for Advanced Studies (IAS) of Wuhan University. In contrast to the classic coupling reactions between Electrophile (E)/Nucleophile (Nu), utilizing Nu1/Nu2, Aiwen Lei developed a new bond forming strategy: “Oxidative Cross-coupling”. He and his group can selectively couple the following pairs R1M1/ R2M2, R1H/R2M, and R1-H/R2H using stoichiometric external oxidants. Gratifyingly, without utilizing extra oxidant, R1-H/R2-H can be selectively cross-coupled, along with H2-evolution, through photoor electrochemistry. In 2015, he became a Fellow of the Royal Society of Chemistry (FRSC) and has won many awards, such as the Roche Chinese Young Investigator Award (2015), the Eli Lilly Scientific Excellence Award in Chemistry (2011), and the CAPA Distinguished Faculty Award (2009), among many others.
REFERENCES (1) Fenton, H. J. H. Oxidation of tartaric acid in presence of iron. J. Chem. Soc., Trans. 1894, 65, 899−911. (2) Shilov, A. E.; Shul’pin, G. B. Activation of C-H bonds by metal complexes. Chem. Rev. 1997, 97, 2879−2932. (3) Labinger, J. A. Platinum-Catalyzed C−H Functionalization. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00583. (4) Schwach, P.; Pan, X.; Bao, X. Direct Conversion of Methane to Value-Added Chemicals over Heterogeneous Catalysts: Challenges and Prospects. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00715. (5) Gunsalus, N. J.; Koppaka, A.; Park, S. H.; Bischof, S. M.; Hashiguchi, B. G.; Periana, R. A. Homogeneous Functionalization of Methane. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00739. (6) Wang, V. C. C.; Maji, S.; Chen, P. P. Y.; Lee, H. K.; Yu, S. S. F.; Chan, S. Y. Alkane Oxidation: Methane Monooxygenases, Related Enzymes, and Their Biomimetics. Chem. Rev. 2017, DOI: 10.1021/ acs.chemrev.6b00624. (7) Xue, X. S.; Ji, P.; Zhou, B.; Cheng, J. P. The Essential Role of Bond Energetics in C−H Activation/Functionalization. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00664. 8482
DOI: 10.1021/acs.chemrev.7b00307 Chem. Rev. 2017, 117, 8481−8482
