1
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Abstract
When searching for the ideal molecule to fill a particular functional role (for example, a medicine), the difference between success and failure can often come down to a single atom1. Replacing an aromatic carbon atom with a nitrogen atom would be enabling in the discovery of potential medicines2, but only indirect means exist to make such C-to-N transmutations, typically by parallel synthesis3. Here, we report a transformation that enables the direct conversion of a heteroaromatic carbon atom into a nitrogen atom, turning quinolines into quinazolines. Oxidative restructuring of the parent azaarene gives a ring-opened intermediate bearing electrophilic sites primed for ring reclosure and expulsion of a carbon-based leaving group. Such a 'sticky end' approach subverts existing atom insertion-deletion approaches and as a result avoids skeleton-rotation and substituent-perturbation pitfalls common in stepwise skeletal editing. We show a broad scope of quinolines and related azaarenes, all of which can be converted into the corresponding quinazolines by replacement of the C3 carbon with a nitrogen atom. Mechanistic experiments support the critical role of the activated intermediate and indicate a more general strategy for the development of C-to-N transmutation reactions.
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Affiliation(s)
- Jisoo Woo
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
| | - Colin Stein
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
| | | | - Mark D Levin
- Department of Chemistry, The University of Chicago, Chicago, IL, USA.
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2
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Gonzalez-Valero A, Reeves AG, Page ACS, Moon PJ, Miller E, Coulonval K, Crossley SWM, Xie X, He D, Musacchio PZ, Christian AH, McKenna JM, Lewis RA, Fang E, Dovala D, Lu Y, McGregor LM, Schirle M, Tallarico JA, Roger PP, Toste FD, Chang CJ. An Activity-Based Oxaziridine Platform for Identifying and Developing Covalent Ligands for Functional Allosteric Methionine Sites: Redox-Dependent Inhibition of Cyclin-Dependent Kinase 4. J Am Chem Soc 2022; 144:22890-22901. [PMID: 36484997 PMCID: PMC10124963 DOI: 10.1021/jacs.2c04039] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Activity-based protein profiling (ABPP) is a versatile strategy for identifying and characterizing functional protein sites and compounds for therapeutic development. However, the vast majority of ABPP methods for covalent drug discovery target highly nucleophilic amino acids such as cysteine or lysine. Here, we report a methionine-directed ABPP platform using Redox-Activated Chemical Tagging (ReACT), which leverages a biomimetic oxidative ligation strategy for selective methionine modification. Application of ReACT to oncoprotein cyclin-dependent kinase 4 (CDK4) as a representative high-value drug target identified three new ligandable methionine sites. We then synthesized a methionine-targeting covalent ligand library bearing a diverse array of heterocyclic, heteroatom, and stereochemically rich substituents. ABPP screening of this focused library identified 1oxF11 as a covalent modifier of CDK4 at an allosteric M169 site. This compound inhibited kinase activity in a dose-dependent manner on purified protein and in breast cancer cells. Further investigation of 1oxF11 found prominent cation-π and H-bonding interactions stabilizing the binding of this fragment at the M169 site. Quantitative mass-spectrometry studies validated 1oxF11 ligation of CDK4 in breast cancer cell lysates. Further biochemical analyses revealed cross-talk between M169 oxidation and T172 phosphorylation, where M169 oxidation prevented phosphorylation of the activating T172 site on CDK4 and blocked cell cycle progression. By identifying a new mechanism for allosteric methionine redox regulation on CDK4 and developing a unique modality for its therapeutic intervention, this work showcases a generalizable platform that provides a starting point for engaging in broader chemoproteomics and protein ligand discovery efforts to find and target previously undruggable methionine sites.
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Affiliation(s)
- Angel Gonzalez-Valero
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Audrey G. Reeves
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Annika C. S. Page
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Patrick J. Moon
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Edward Miller
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Katia Coulonval
- Faculté de Médecine, Institute of Interdisciplinary Research, Université Libre de Bruxelles, Campus Erasme, Brussels 1070, Belgium
| | - Steven W. M. Crossley
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Xiao Xie
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Dan He
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Patricia Z. Musacchio
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Alec H. Christian
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Jeffrey M. McKenna
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Richard A. Lewis
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Eric Fang
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Dustin Dovala
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Yipin Lu
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Lynn M. McGregor
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Markus Schirle
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - John A. Tallarico
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Pierre P. Roger
- Faculté de Médecine, Institute of Interdisciplinary Research, Université Libre de Bruxelles, Campus Erasme, Brussels 1070, Belgium
| | - F. Dean Toste
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Christopher J. Chang
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
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3
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He D, Feng H, Sundberg B, Yang J, Powers J, Christian AH, Wilkinson JE, Monnin C, Avizonis D, Thomas CJ, Friedman RA, Kluger MD, Hollingsworth MA, Grandgenett PM, Klute KA, Toste FD, Chang CJ, Chio IIC. Methionine oxidation activates pyruvate kinase M2 to promote pancreatic cancer metastasis. Mol Cell 2022; 82:3045-3060.e11. [PMID: 35752173 PMCID: PMC9391305 DOI: 10.1016/j.molcel.2022.06.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 04/06/2022] [Accepted: 06/02/2022] [Indexed: 02/07/2023]
Abstract
Cancer mortality is primarily a consequence of its metastatic spread. Here, we report that methionine sulfoxide reductase A (MSRA), which can reduce oxidized methionine residues, acts as a suppressor of pancreatic ductal adenocarcinoma (PDA) metastasis. MSRA expression is decreased in the metastatic tumors of PDA patients, whereas MSRA loss in primary PDA cells promotes migration and invasion. Chemoproteomic profiling of pancreatic organoids revealed that MSRA loss results in the selective oxidation of a methionine residue (M239) in pyruvate kinase M2 (PKM2). Moreover, M239 oxidation sustains PKM2 in an active tetrameric state to promote respiration, migration, and metastasis, whereas pharmacological activation of PKM2 increases cell migration and metastasis in vivo. These results demonstrate that methionine residues can act as reversible redox switches governing distinct signaling outcomes and that the MSRA-PKM2 axis serves as a regulatory nexus between redox biology and cancer metabolism to control tumor metastasis.
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Affiliation(s)
- Dan He
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Huijin Feng
- Institute for Cancer Genetics, Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA; Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Belen Sundberg
- Institute for Cancer Genetics, Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA; Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Jiaxing Yang
- Institute for Cancer Genetics, Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA; Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Justin Powers
- Institute for Cancer Genetics, Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA; Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Alec H Christian
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | | | - Cian Monnin
- Metabolomics Innovation Resource, Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC H3A 1A3, Canada
| | - Daina Avizonis
- Metabolomics Innovation Resource, Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC H3A 1A3, Canada
| | - Craig J Thomas
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD 20850, USA; Lymphoid Malignancies Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Richard A Friedman
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Biomedical Informatics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Michael D Kluger
- Division of Gastrointestinal & Endocrine Surgery, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Michael A Hollingsworth
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Paul M Grandgenett
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kelsey A Klute
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - F Dean Toste
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Christopher J Chang
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
| | - Iok In Christine Chio
- Institute for Cancer Genetics, Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA; Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA.
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4
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Abstract
Discovery chemists routinely identify purpose-tailored molecules through an iterative structural optimization approach, but the preparation of each successive candidate in a compound series can rarely be conducted in a manner matching their thought process. This is because many of the necessary chemical transformations required to modify compound cores in a straightforward fashion are not applicable in complex contexts. We report a method that addresses one facet of this problem by allowing chemists to hop directly between chemically distinct heteroaromatic scaffolds. Specifically, we show that selective photolysis of quinoline N-oxides with 390-nanometer light followed by acid-promoted rearrangement affords N-acylindoles while showing broad compatibility with medicinally relevant functionality. Applications to late-stage skeletal modification of compounds of pharmaceutical interest and more complex transformations involving serial single-atom changes are demonstrated.
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Affiliation(s)
- Jisoo Woo
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | | | | | - Yuan Jiang
- Analytical Research and Development, Merck & Co., Inc., Boston, MA, USA
| | | | - Mark D Levin
- Department of Chemistry, University of Chicago, Chicago, IL, USA
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5
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Christian AH. Metallaphotoredox-Catalyzed C-S Cross-Coupling between Heteroaryl Bromides and α-Thioacetic Acids to Access Biaryl Thioethers. J Org Chem 2021; 86:10914-10920. [PMID: 34260227 DOI: 10.1021/acs.joc.1c01309] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Metallaphotoredox-catalyzed C-S cross-coupling between heteroaryl bromides and α-thioacetic acids to form biaryl thioethers is described herein. This transformation allows for cross-coupling between building blocks containing reactive functional groups, nitrogen heterocycles, and pharmaceutically relevant scaffolds. Mechanistic experiments indicate a unique means by which this C-S cross-coupling occurs.
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Affiliation(s)
- Alec H Christian
- Discovery Chemistry, Merck & Co., Inc., 33 Avenue Louis Pasteur, Boston, Massachusetts 02115, United States
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6
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Beavers WN, DuMont AL, Monteith AJ, Maloney KN, Tallman KA, Weiss A, Christian AH, Toste FD, Chang CJ, Porter NA, Torres VJ, Skaar EP. Staphylococcus aureus Peptide Methionine Sulfoxide Reductases Protect from Human Whole-Blood Killing. Infect Immun 2021; 89:e0014621. [PMID: 34001560 PMCID: PMC8281210 DOI: 10.1128/iai.00146-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/07/2021] [Indexed: 11/20/2022] Open
Abstract
The generation of oxidative stress is a host strategy used to control Staphylococcus aureus infections. Sulfur-containing amino acids, cysteine and methionine, are particularly susceptible to oxidation because of the inherent reactivity of sulfur. Due to the constant threat of protein oxidation, many systems evolved to protect S. aureus from protein oxidation or to repair protein oxidation after it occurs. The S. aureus peptide methionine sulfoxide reductase (Msr) system reduces methionine sulfoxide to methionine. Staphylococci have four Msr enzymes, which all perform this reaction. Deleting all four msr genes in USA300 LAC (Δmsr) sensitizes S. aureus to hypochlorous acid (HOCl) killing; however, the Δmsr strain does not exhibit increased sensitivity to H2O2 stress or superoxide anion stress generated by paraquat or pyocyanin. Consistent with increased susceptibility to HOCl killing, the Δmsr strain is slower to recover following coculture with both murine and human neutrophils than USA300 wild type. The Δmsr strain is attenuated for dissemination to the spleen following murine intraperitoneal infection and exhibits reduced bacterial burdens in a murine skin infection model. Notably, no differences in bacterial burdens were observed in any organ following murine intravenous infection. Consistent with these observations, USA300 wild-type and Δmsr strains have similar survival phenotypes when incubated with murine whole blood. However, the Δmsr strain is killed more efficiently by human whole blood. These findings indicate that species-specific immune cell composition of the blood may influence the importance of Msr enzymes during S. aureus infection of the human host.
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Affiliation(s)
- William N. Beavers
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Ashley L. DuMont
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Andrew J. Monteith
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - K. Nichole Maloney
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Keri A. Tallman
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Andy Weiss
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Alec H. Christian
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA
| | - F. Dean Toste
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA
| | - Christopher J. Chang
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Ned A. Porter
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Victor J. Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
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7
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Abstract
This review will cover the importance of and most recent approaches toward geminal difluoroalkyl groups. Transition metal-mediated, photochemical, organocatalytic, and other methods as well as their mechanistic implications will be discussed, with special emphasis on applications to biologically-relevant compounds.
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Affiliation(s)
- Dayanne R Carvalho
- Discovery Chemistry, Merck & Co., Inc., 33 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA.
| | - Alec H Christian
- Discovery Chemistry, Merck & Co., Inc., 33 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA.
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8
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Elledge SK, Tran HL, Christian AH, Steri V, Hann B, Toste FD, Chang CJ, Wells JA. Systematic identification of engineered methionines and oxaziridines for efficient, stable, and site-specific antibody bioconjugation. Proc Natl Acad Sci U S A 2020; 117:5733-5740. [PMID: 32123103 PMCID: PMC7084160 DOI: 10.1073/pnas.1920561117] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The field of chemical modification of proteins has been dominated by random modification of lysines or more site-specific labeling of cysteines, each with attendant challenges. Recently, we have developed oxaziridine chemistry for highly selective modification of methionine called redox-activated chemical tagging (ReACT) but have not broadly tested the molecular parameters for efficient and stable protein modification. Here we systematically scanned methionines throughout one of the most popular antibody scaffolds, trastuzumab, used for antibody engineering and drug conjugation. We tested the expression, reactivities, and stabilities of 123 single engineered methionines distributed over the surface of the antibody when reacted with oxaziridine. We found uniformly high expression for these mutants and excellent reaction efficiencies with a panel of oxaziridines. Remarkably, the stability to hydrolysis of the sulfimide varied more than 10-fold depending on temperature and the site of the engineered methionine. Interestingly, the most stable and reactive sites were those that were partially buried, presumably because of their reduced access to water. There was also a 10-fold variation in stability depending on the nature of the oxaziridine, which was determined to be inversely correlated with the electrophilic nature of the sulfimide. Importantly, the stabilities of the best analogs were sufficient to support their use as antibody drug conjugates and potent in a breast cancer mouse xenograft model over a month. These studies provide key parameters for broad application of ReACT for efficient, stable, and site-specific antibody and protein bioconjugation to native or engineered methionines.
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Affiliation(s)
- Susanna K Elledge
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158
| | - Hai L Tran
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158
| | - Alec H Christian
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Veronica Steri
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
- Preclinical Therapeutics Core, University of California, San Francisco, CA 94158
| | - Byron Hann
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
- Preclinical Therapeutics Core, University of California, San Francisco, CA 94158
| | - F Dean Toste
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Christopher J Chang
- Department of Chemistry, University of California, Berkeley, CA 94720
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
| | - James A Wells
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158;
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158
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9
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Christian AH, Jia S, Cao W, Zhang P, Meza AT, Sigman MS, Chang CJ, Toste FD. A Physical Organic Approach to Tuning Reagents for Selective and Stable Methionine Bioconjugation. J Am Chem Soc 2019; 141:12657-12662. [PMID: 31361488 PMCID: PMC6781863 DOI: 10.1021/jacs.9b04744] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We report a data-driven, physical organic approach to the development of new methionine-selective bioconjugation reagents with tunable adduct stabilities. Statistical modeling of structural features described by intrinsic physical organic parameters was applied to the development of a predictive model and to gain insight into features driving the stability of adducts formed from the chemoselective coupling of oxaziridine and methionine thioether partners through Redox Activated Chemical Tagging (ReACT). From these analyses, a correlation between sulfimide stabilities and sulfimide ν (C═O) stretching frequencies was revealed. We exploited the rational gains in adduct stability exposed by this analysis to achieve the design and synthesis of a bis-oxaziridine reagent for peptide stapling. Indeed, we observed that a macrocyclic peptide formed by ReACT stapling at methionine exhibited improved uptake into live cells compared to an unstapled congener, highlighting the potential utility of this unique chemical tool for thioether modification. This work provides a template for the broader use of data-driven approaches to bioconjugation chemistry and other chemical biology applications.
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Affiliation(s)
- Alec H. Christian
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Shang Jia
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Wendy Cao
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Patricia Zhang
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Arismel Tena Meza
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Matthew S. Sigman
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Christopher J. Chang
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
- Howard Hughes Medical Institute, University of California, Berkeley, California 94720, United States
| | - F. Dean Toste
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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10
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Abstract
Herein, we report the integration of simple linear regressions with gold(I) catalysis to interrogate the influence of phosphine structure on metal-catalyzed organic transformations. We demonstrate that observed product ratios in [4 + 3]/[4 + 2] cycloisomerization processes are influenced by both steric and electronic properties of the phosphine, which can be represented by the Au-Cl distance. In contrast, the observed selectivity of a similar [2 + 3]/[2 + 2] cycloisomerization is governed by L/B1, a steric parameter. Using this correlation, we were able to accurately predict the selectivity of a previously untested, Buchwald-type ligand to enhance selectivity for the same transformation. This ligand found further utility in increasing the selectivity of a previously reported gold-catalyzed cycloisomerization/arylation of 1,6-enynes by ~1 kcal/mol.
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Affiliation(s)
- Alec H. Christian
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Zachary L. Niemeyer
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Matthew S. Sigman
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - F. Dean Toste
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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11
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Affiliation(s)
- Alec H. Christian
- Worldwide Research and Development, Pfizer Inc., Eastern
Point Road, Groton, Connecticut 06340, United States
| | - Peter Müller
- Department of Chemistry 6-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Sebastien Monfette
- Worldwide Research and Development, Pfizer Inc., Eastern
Point Road, Groton, Connecticut 06340, United States
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