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Introduction to the Virtual Issue Honoring Robert Bergman’s 2017 Wolf Prize in Chemistry In honor of Bob’s well-deserved award, Organometallics is excited to publish this Virtual Issue honoring his recent contributions to the journal. One notable feature of Bob’s papers highlighted in this issue is their topical diversity. Each publication presents top-quality organometallic chemistry, while the applications touch various aspects of small-molecule activation, catalysis, and mechanistic studies. Many of these recent papers were conducted in collaboration with colleagues at UC Berkeley. Examples include understanding reductive elimination in platinum compounds from a collaboration with Don Tilley and co-workers6 and work that was featured on the cover of issue 8 in 2016 on the synthesis of gold pincer compounds in collaboration with Dean Toste and co-workers.7 Other articles featured from collaborations with Don Tilley and his group include a mechanistic study differentiating the role of Brønsted acids in platinum-catalyzed hydroarylation chemistry8 and synthesis of a dicationic platinum complex that is competent for allylic C−H activation in protic media.9 But the Wolf prize is about C−H activation, after all. So it is only appropriate that here we also include some of Bob’s more “classic” publications in Organometallics. His most cited Organometallics paper10 is one coauthored with then-graduate student Patrick Walsh and X-ray crystallographer Frederick Hollander on zirconocene imido complexes. These findings were contemporaneous with those made by Peter Wolczanski11 with non-metallocene titanium and zirconium imido complexes and opened the era of C−H activation by 1,2-addition across a metal−ligand multiple bond. On a more personal note, it is these papers that inspired the work of my group on the hydrogenation and functionalization of molecular nitrogen by 1,2-addition.12 Other classic Bergman papers included in this issue are a paper coauthored with Jonathan Ellman and colleagues13 on the role of preagostic rhodium hydride interactions in C−H bond functionalization and one of my personal favorites, an article in collaboration again with Don Tilley et al.14 on cyclopentadienyl iridium and rhodium(III) complexes with pendant phosphines that promote hydrogen isotope exchange with hydrocarbons using D2O. Bob has also served as a mentor to numerous graduate students, postdocs, and visiting scientists that have come through his laboratories both at Caltech and at UC Berkeley. While the contributions of these outstanding scientists often extend far beyond the realm of academic publishing and Organometallics, some of their papers published in the journal principally after 2013 are also featured in this Virtual Issue. What is noteworthy is the breadth of disciplines and the types of organometallic chemistry undertaken by the former members of the Bergman research group. The contribution from Bill Jones and co-workers15 reports the cleavage of carbon−nitrile bonds by palladium complexes, an important and longstanding problem in the synthesis of Nylon precursors.
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he impact of organometallic chemistry on organic synthesis is undisputed. It is now commonplace to find cross-coupling reactions, alkene hydrogenations, and olefin metathesis processes as key steps during the synthesis of complex molecular targets. In contemporary organometallic chemistry and homogeneous catalysis, C−H functionalization is entering this pantheon and has transitioned from an academic challenge to a transformative tool in organic synthesis.1,2 C−H functionalization is also one of the most actively pursued topics at the interfaces of organometallic chemistry, catalysis, and organic methodology. Where did it all begin, and how did we get here? Like most impactful organometallic transformations, modern C−H activation methods can be traced to landmark studies in fundamental reactivity and mechanism. In 1982, a communication entitled “C−H Activation in Completely Saturated HydrocarbonsDirect Observation of M + R−H → M(R)”3 was published in the Journal of the American Chemical Society that, along with a subsequent paper from W. A. G. Graham,4 ushered in the modern age of metal-promoted C−H activation. The lead author on this paper was Robert G. Bergman, the Gerald E. K. Branch Distinguished Professor at the University of CaliforniaBerkeley and the 2017 winner of the Wolf Prize in Chemistry. The Wolf Prizes are international, highly visible, and prestigious prizes awarded each year in six disciplines. The citation for this year’s Chemistry Prize is for “[Bergman’s] discovery of the activation responses of carbon−hydrogen bonds in hydrocarbons by soluble organometallic complexes”. As many of our readers know, Bob is a fixture in our community and one of the most visible members in organometallic chemistry. He is a frequent author in Organometallics and since the inception of the journal has published nearly 100 papers with us. This prolific activity places him among the top 25 submitting authors of all time. Like many of the founding members of contemporary organometallic chemistry, Bob was trained as a physical organic chemist, having earned his Ph.D. at the University of Wisconsin Madison with Jerome Berson. In fact, one of Bob’s signature contributions from his early independent career is the so-called “Bergman cyclization”, the thermal cyclization of cis-1,5hexadiyn-3-enes to benzene-1,4-diradicals.5 Like much of Bob’s chemistry, what began as a fundamental investigation into an interesting chemical transformation evolved into something with much more practical impact. The Bergman cyclization has been identified as a key pathway in DNA cleavage with antibitiotics that bind to nucleic acids and has been an inspiration for the synthesis of complex molecules with specific biological functions. Bob, in his research then at Caltech and later at UC Berkeley, transitioned into organometallic chemistry and has been a prolific researcher with interests ranging from C−H activation to homogeneous catalysis and more recently biomass conversion and conducting catalytic reactions in well-defined molecular containers. © 2017 American Chemical Society
Published: March 13, 2017 957
DOI: 10.1021/acs.organomet.7b00134 Organometallics 2017, 36, 957−959
Organometallics
Editor's Page
In closing, this is another great time and cause for celebration for organometallic chemistry! Once again, fundamental curiosity of how transition metals do remarkable things with organic molecules and figuring out the how and the why has resulted in evolution to a transformative synthetic method that is only now beginning to reach its potential. So, a hearty and well-deserved congratulations to Bob Bergman and best wishes for future development of this exciting area of science. One is left to ponder: with a recognition so notable as the Wolf Prize in Chemistry, could a call from Stockholm be next? Stay tuned!
Other palladium chemistry includes a study from Karen Goldberg and collaborators Rick Kemp et al. on C−H activation by pincer-supported hydroxide complexes.16 Anna Badaj and Gino Lavoie17 describe the preparation of palladium methyl complexes that undergo unusual ligand-based modifications upon treatment with isocyanides. These papers, along with the contribution from Bruce Arndtsen’s group18 on the mechanism of oxidative addition of haloalkanes to cyclopentadienyl rhenium complexes, are quintessential Bergmantype chemistry: scholarly, mechanistically focused fundamental science. While Bob is well-known for his work with iridium, rhodium, and ruthenium, some of his earliest work in organometallic chemistry involved first-row transition metals such as vanadium19 and cobalt.20 Not surprisingly, many of the papers in this issue feature organometallic chemistry and catalysis with first-row transition metals. Jennifer Schomaker and co-workers report a nickel-catalyzed method for the Markovnikov selective hydroboration of styrenes,21 and Jeffrey Stryker et al. describe cobalt-catalyzed cycloadditions.22 Shane Krska, a former Bergman postdoc and currently a senior chemist at Merck, coauthored a paper with my laboratory on developing iron dialkyl catalysts for the asymmetric hydrogenation of alkenes.23 The contribution from Sarina Bellows, Thomas Cundari, and Patrick Holland24 explores the role spin crossover processes play in β-hydrogen elimination reactions with high-spin iron(II) and cobalt(II) alkyl complexes with “nacnac”-type ligands. Fitting with the citation of the Wolf Prize, C−H activation reactions are also prominently featured in the issue. Landon Durak and Jared Lewis25 report a dual-metal process where palladium cross-coupling and the resulting C−H arylation is enabled by iridium-promoted C−H activation. A theoretical paper from Roy Periana, Daniel Ess, and co-workers26 explores the possibility of C−H activation with main-group elements and what mechanisms are plausible to promote such chemistry. This is an emerging and exciting area of organometallic chemistry, one we hope to see more prominently featured in future issues of Organometallics. Other contributions include one from Bernd Straub et al. on selective routes to heterobimetallic NHC complexes,27 Patrick Walsh, Marisa Kozlowski, and co-workers28 on alkenes as chelating groups in zinc-mediated additions to ketones, and Christina Rotsides and Keith Woerpel’s mechanistic study of insertion reactions with silacyclopropanes.29 Suzanne Blum and co-workers30 uncover an interesting and “non-innocent” role for sodium chloride in a kinetic study of Lewis acid catalyzed oxyboration, and a collaborative paper from Rory Waterman, Dave Morris, Jaqueline Kiplinger, et al.31 describes the rich chemistry available with heavy elements and reports silane dehydrogenation chemistry with uranium hydrides. The final paper is from one of our Associate Editors, Laurel Schafer.32 The work was in collaboration with Rhett Kempe and colleagues and reports titanium aminopyridinate complexes for catalytic hydroamination chemistry. The scientific relationship to Bergman’s work is clear, as Bob has been a pioneer in hydroamination catalysis, particularly with early transition metals. What is more telling was Laurel’s motivation for inclusion in this issue. Though Laurel never spent time in Bob’s group, she was a postdoc with Don Tilley. Like many of us, Bob has been an informal mentor and friend throughout our careers. It is both an honor and a pleasure to collate this excellent body of articles in celebration of his Wolf Prize in Chemistry.
Paul J. Chirik, Editor-in-Chief
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Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
AUTHOR INFORMATION
ORCID
Paul J. Chirik: 0000-0001-8473-2898 Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS.
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REFERENCES
(1) Hartwig, J. F. J. Am. Chem. Soc. 2016, 138, 2. (2) Hartwig, J. F.; Larsen, M. A. ACS Cent. Sci. 2016, 2, 281. (3) Janowicz, A. H.; Bergman, R. G. J. Am. Chem. Soc. 1982, 104, 352. (4) Hoyano, J. K.; Graham, W. A. J. Am. Chem. Soc. 1982, 104, 3723. (5) Jones, R. R.; Bergman, R. G. J. Am. Chem. Soc. 1972, 94, 660. (6) Liberman-Martin, A. L.; Levine, D. S.; Liu, W.; Bergman, R. G.; Tilley, T. D. Organometallics 2016, 35, 1064. (7) Johnson, M. W.; DiPasquale, A. G.; Bergman, R. G.; Toste, F. D. Organometallics 2014, 33, 4169. (8) Bowring, M. A.; Bergman, R. G.; Tilley, T. D. Organometallics 2011, 30, 1295. (9) Bowring, M. A.; Bergman, R. G.; Tilley, T. D. Organometallics 2013, 32, 5266. (10) Walsh, P. J.; Hollander, F. J.; Bergman, R. G. Organometallics 1993, 12, 3705. (11) (a) Bennett, J. L.; Wolczanski, P. T. J. Am. Chem. Soc. 1997, 119, 10696. (b) Cummins, C. C.; Baxter, S. M.; Wolczanski, P. T. J. Am. Chem. Soc. 1988, 110, 8731. (12) (a) Pool, J. A.; Lobkovsky, E.; Chirik, P. J. Nature 2004, 427, 527. (b) Pool, J. A.; Bernskoetter, W. H.; Chirik, P. J. J. Am. Chem. Soc. 2004, 126, 14326. (c) Bernskoetter, W. H.; Lobkovsky, E.; Chirik, P. J. J. Am. Chem. Soc. 2005, 127, 14051. (13) Lewis, J. C.; Wu, J.; Bergman, R. G.; Ellman, J. A. Organometallics 2005, 24, 5737. (14) Klei, S. R.; Tilley, T. D.; Bergman, R. G. Organometallics 2002, 21, 4905. (15) Munjanja, L.; Torres-López, C.; Brennessel, W. W.; Jones, W. D. Organometallics 2016, 35, 2010. (16) Bailey, W. D.; Luconi, L.; Rossin, A.; Yakhvarov, D.; Flowers, S. E.; Kaminsky, W.; Kemp, R. A.; Giambastiani, G.; Goldberg, K. I. Organometallics 2015, 34, 3998. (17) Badaj, A. C.; Lavoie, G. G. Organometallics 2013, 32, 4577. (18) Yempally, V.; Moncho, S.; Muhammad, S.; Brothers, E. N.; Arndtsen, B. A.; Bengali, A. A. Organometallics 2014, 33, 3591. (19) For example, see: Kinney, R. J.; Jones, W. D.; Bergman, R. G. J. Am. Chem. Soc. 1978, 100, 635. (20) For example, see: (a) Vollhardt, K. P.; Bercaw, J. E.; Bergman, R. G. J. Am. Chem. Soc. 1974, 96, 4998. (b) Schore, N. E.; Ilenda, C.; Bergman, R. G. J. Am. Chem. Soc. 1976, 98, 7436. (21) Touney, E. E.; Van Hoveln, R.; Buttke, C. T.; Freidberg, M. D.; Guzei, I. A.; Schomaker, J. M. Organometallics 2016, 35, 3436. (22) Ylijoki, K. E. O.; Kirk, A. D.; Böcklein, S.; Witherell, R. D.; Stryker, J. M. Organometallics 2015, 34, 3335. 958
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Organometallics
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(23) Hoyt, J. M.; Shevlin, M.; Margulieux, G. W.; Krska, S. W.; Tudge, M. T.; Chirik, P. J. Organometallics 2014, 33, 5781. (24) Bellows, S. M.; Cundari, T. R.; Holland, P. L. Organometallics 2013, 32, 4741. (25) Durak, L. J.; Lewis, J. C. Organometallics 2014, 33, 620. (26) King, C. R.; Gustafson, S. J.; Black, B. R.; Butler, S. K.; Konnick, M. M.; Periana, R. A.; Hashiguchi, B. M.; Ess, D. H. Organometallics 2017, 36, 109. (27) Seitz, S. C.; Rominger, F.; Straub, B. F. Organometallics 2013, 32, 2427. (28) Raffier, L.; Gutierrez, O.; Stanton, G. R.; Kozlowski, M. C.; Walsh, P. J. Organometallics 2014, 33, 5371. (29) Rotsides, C. Z.; Woerpel, K. A. Organometallics 2016, 35, 3132. (30) Johnson, J. S.; Chong, E.; Tu, K. N.; Blum, S. A. Organometallics 2016, 35, 655. (31) Pagano, J. K.; Dorhout, J. M.; Czerwinski, K. R.; Morris, D. E.; Scott, B. L.; Waterman, R.; Kiplinger, J. L. Organometallics 2016, 35, 617. (32) Chong, E.; Qayyum, S.; Schafer, L. L.; Kempe, R. Organometallics 2013, 32, 1858.
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DOI: 10.1021/acs.organomet.7b00134 Organometallics 2017, 36, 957−959
