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Blythe IM, Xu J, Fernandez Odell JS, Kampf JW, Bowring MA, Sanford MS. Characterization and Reactivity of Copper(II) and Copper(III) σ-Aryl Intermediates in Aminoquinoline-Directed C-H Functionalization. J Am Chem Soc 2023; 145:18253-18259. [PMID: 37552536 DOI: 10.1021/jacs.3c00914] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
Over the past decade, numerous reports have focused on the development and applications of Cu-mediated C-H functionalization reactions; however, to date, little is known about the Cu intermediates involved in these transformations. This paper details the observation and characterization of CuII and CuIII intermediates in aminoquinoline-directed C(sp2)-H functionalization of a fluoroarene substrate. An initial C(sp2)-H activation at CuII occurs at room temperature to afford an isolable anionic cyclometalated CuII complex. This complex undergoes single-electron oxidation with ferrocenium or AgI salts under mild conditions (5 min at room temperature) to afford C(sp2)-C(sp2) or C(sp2)-NO2 coupling products. Spectroscopic studies implicate the formation of a transient diamagnetic CuIII-σ-aryl intermediate that undergoes either (i) a second C(sp2)-H activation at CuIII followed by C-C bond-forming reductive elimination or (ii) reaction with a NO2- nucleophile and C(sp2)-NO2 coupling.
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Affiliation(s)
- Isaac M Blythe
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Jingtong Xu
- Department of Chemistry, Reed College, 3203 Woodstock Boulevard, Portland, Oregon 97202, United States
| | - Joaquin S Fernandez Odell
- Department of Chemistry, Reed College, 3203 Woodstock Boulevard, Portland, Oregon 97202, United States
| | - Jeff W Kampf
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Miriam A Bowring
- Department of Chemistry, Reed College, 3203 Woodstock Boulevard, Portland, Oregon 97202, United States
| | - Melanie S Sanford
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
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Rettig ID, Xu J, Knight EA, Truong PT, Bowring MA. Variable Kinetic Isotope Effect Reveals a Multistep Pathway for Protonolysis of a Pt–Me Bond. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Irving D. Rettig
- Department of Chemistry, Reed College, Portland, Oregon97202, United States
| | - Jingtong Xu
- Department of Chemistry, Reed College, Portland, Oregon97202, United States
| | | | - Phan T. Truong
- Department of Chemistry, Reed College, Portland, Oregon97202, United States
| | - Miriam A. Bowring
- Department of Chemistry, Reed College, Portland, Oregon97202, United States
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3
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Abstract
The kinetic isotope effect (KIE) is key to understanding reaction mechanisms in many areas of chemistry and chemical biology, including organometallic chemistry. This ratio of rate constants, kH /kD , typically falls between 1-7. However, KIEs up to 105 have been reported, and can even be so large that reactivity with deuterium is unobserved. We collect here examples of large KIEs across organometallic chemistry, in catalytic and stoichiometric reactions, along with their mechanistic interpretations. Large KIEs occur in proton transfer reactions such as protonation of organometallic complexes and clusters, protonolysis of metal-carbon bonds, and dihydrogen reactivity. C-H activation reactions with large KIEs occur with late and early transition metals, photogenerated intermediates, and abstraction by metal-oxo complexes. We categorize the mechanistic interpretations of large KIEs into the following three types: (a) proton tunneling, (b) compound effects from multiple steps, and (c) semi-classical effects on a single step. This comprehensive collection of large KIEs in organometallics provides context for future mechanistic interpretation.
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Affiliation(s)
- Phan T Truong
- Department of Chemistry, Reed College, 3203 SE Woodstock Blvd., Portland, OR 97222
| | - Sophia G Miller
- Department of Chemistry, Reed College, 3203 SE Woodstock Blvd., Portland, OR 97222
| | | | - Miriam A Bowring
- Department of Chemistry, Reed College, 3203 SE Woodstock Blvd., Portland, OR 97222
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4
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Truong PT, Miller SG, McLaughlin Sta. Maria EJ, Bowring MA. Frontispiece: Large Isotope Effects in Organometallic Chemistry. Chemistry 2021. [DOI: 10.1002/chem.202186061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Phan T. Truong
- Department of Chemistry Reed College 3203 SE Woodstock Blvd. Portland OR 97222
| | - Sophia G. Miller
- Department of Chemistry Reed College 3203 SE Woodstock Blvd. Portland OR 97222
| | | | - Miriam A. Bowring
- Department of Chemistry Reed College 3203 SE Woodstock Blvd. Portland OR 97222
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Abstract
Air-free glassware and techniques are used in most organometallic research laboratories, but their relative effectiveness has not been well studied. We report a method for quantitatively comparing air and moisture exclusion by air-free glassware. Samples of benzophenone dianion in various glassware are monitored by video as their purple color is quenched. Numerical values for time until colorless are extracted from the video data and interpreted as a relative measure of air and moisture exclusion. Low pressure/vacuum (LPV) NMR tubes demonstrated by far the best performance, compared to a variety of Schlenk flasks and standard NMR tubes. The findings are of immediate practical use for synthetic chemists, and the evaluation methods can be used by individual laboratories to assess other conditions for air and moisture exclusion.
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Affiliation(s)
| | | | - Ellis D Douma
- Department of Chemistry, Reed College, Portland, Oregon 97202, USA.
| | - Miriam A Bowring
- Department of Chemistry, Reed College, Portland, Oregon 97202, USA.
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6
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Bowring MA, Bradshaw LR, Parada GA, Pollock TP, Fernández-Terán RJ, Kolmar SS, Mercado BQ, Schlenker CW, Gamelin DR, Mayer JM. Activationless Multiple-Site Concerted Proton-Electron Tunneling. J Am Chem Soc 2018; 140:7449-7452. [PMID: 29847111 DOI: 10.1021/jacs.8b04455] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transfer of protons and electrons is key to energy conversion and storage, from photosynthesis to fuel cells. Increased understanding and control of these processes are needed. A new anthracene-phenol-pyridine molecular triad was designed to undergo fast photoinduced multiple-site concerted proton-electron transfer (MS-CPET), with the phenol moiety transferring an electron to the photoexcited anthracene and a proton to the pyridine. Fluorescence quenching and transient absorption experiments in solutions and glasses show rapid MS-CPET (3.2 × 1010 s-1 at 298 K). From 5.5 to 90 K, the reaction rate and kinetic isotope effect (KIE) are independent of temperature, with zero Arrhenius activation energy. From 145 to 350 K, there are only slight changes with temperature. This MS-CPET reaction thus occurs by tunneling of both the proton and electron, in different directions. Since the reaction proceeds without significant thermal activation energy, the rate constant indicates the magnitude of the electron/proton double tunneling probability.
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Affiliation(s)
- Miriam A Bowring
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , United States.,Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States.,Department of Chemistry , Reed College , Portland , Oregon 97202 , United States
| | - Liam R Bradshaw
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
| | - Giovanny A Parada
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , United States
| | - Timothy P Pollock
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
| | - Ricardo J Fernández-Terán
- Department of Chemistry, Ångström Laboratory , Uppsala University , Box 523, SE 75120 Uppsala , Sweden
| | - Scott S Kolmar
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , United States
| | - Brandon Q Mercado
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , United States
| | - Cody W Schlenker
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
| | - Daniel R Gamelin
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
| | - James M Mayer
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , United States.,Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
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Affiliation(s)
- Miriam A. Bowring
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Robert G. Bergman
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - T. Don Tilley
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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Abstract
The catalytic cleavage of two C-C single bonds is achieved by treatment of the hydrocarbon substrate spiro[bicyclo[2.2.1]hept-2-ene-7,1'-cyclopropane] with Pt(II) catalysts such as (Me2bpy)PtPh(NTf2) (Me2bpy = 4,4'-dimethyl-2,2'-bipyridine, NTf2(-) = N(SO2CF3)2(-)). The surprising rearrangement product 1,2,4,7,7a-pentahydroindene is generated in good yield. The mechanism of C-C bond activation is investigated using NMR spectroscopy, electrospray ionization mass spectrometry, and deuterium labeling, along with density functional theory calculations. These studies support an unusual catalytic mechanism in which an initial masked C-H bond activation initiates successive C-C bond cleavage events.
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Affiliation(s)
- Miriam A Bowring
- Department of Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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Hill AD, Zoerb MC, Nguyen SC, Lomont JP, Bowring MA, Harris CB. Determining equilibrium fluctuations using temperature-dependent 2D-IR. J Phys Chem B 2013; 117:15346-55. [PMID: 23844833 DOI: 10.1021/jp403791k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We demonstrate the capability of temperature-dependent 2D-IR to characterize sources of vibrational population transfer. In a model system of iron diene tricarbonyl "piano stool" complexes, this approach reveals symmetry breaking associated with equilibrium fluctuations and differentiates these from fluxional rearrangement. Tricarbonyl(1,3-butadiene)iron and tricarbonyl(1,5-cyclooctadiene)iron are shown to undergo intramolecular vibrational redistribution (IVR) coupled to the wagging motion of their carbonyl ligands. In the case of both molecules, these equilibrium fluctuations are distinguished from chemical exchange behaviors by their temperature dependence and arguments of molecular symmetry.
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Affiliation(s)
- Adam D Hill
- Department of Chemistry, University of California , Berkeley, California 94720, United States
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Bowring MA, Bergman RG, Tilley TD. Disambiguation of Metal and Brønsted Acid Catalyzed Pathways for Hydroarylation with Platinum(II) Catalysts. Organometallics 2011. [DOI: 10.1021/om2000458] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Miriam A. Bowring
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Robert G. Bergman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - T. Don Tilley
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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Abstract
Four factors are delineated that account for the difficulties in identifying and diagnosing manic disorders among children and adolescents. These factors are the low base rate of the disorder, its variable clinical presentation within and across episodes, its symptomatic overlap with more common disorders of childhood, and the constraints placed on symptom expression by the developmental stage of a child. Each of these factors is discussed in terms of its impact on the likelihood of recognizing mania, and strategies are proposed to improve diagnostic accuracy.
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Affiliation(s)
- M A Bowring
- Department of Psychiatry, University of Pittsburgh School of Medicine, PA
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Foreman JW, Bowring MA, Lee J, States B, Segal S. Effect of cystine dimethylester on renal solute handling and isolated renal tubule transport in the rat: a new model of the Fanconi syndrome. Metabolism 1987; 36:1185-91. [PMID: 3683187 DOI: 10.1016/0026-0495(87)90246-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The effect of cystine dimethylester on the renal handling of phosphate, glucose, alpha-amino nitrogen, amino acids, and protein in vivo and on the uptake of lysine, glycine, taurine, and alpha-methyl glucoside by isolated renal tubules in vitro was studied in adult male rats. Parenteral administration of 400 mumol twice a day for four days of cystine dimethylester led to an increased urine volume, and excretion of phosphate, glucose, alpha-amino nitrogen, and the amino acids glutamine, proline, alanine, 1/2 cystine, ornithine, lysine, histidine, and glycine. Cystine dimethylester treatment did not affect the creatine clearance nor were any renal anatomic abnormalities noted. Intracellular cysteine, but not cystine, was increased in the kidney after the four days of treatment. Pre-incubation of isolated renal tubules with 2 mmol/L cystine dimethylester for ten minutes markedly inhibited the uptake of 0.025 mmol/L lysine, 0.1 mmol/L glycine, 0.01 mmol/L taurine, and 2 mmol/L alpha-methyl glucoside. Incubation with 2 mmol/L cystine dimethylester for ten minutes did not affect the ability of the renal tubule to exclude trypan blue dye, although longer incubation times did lead to significant staining. The intracellular cystine concentration of the renal tubule did rise significantly after incubation with cystine dimethylester, a biochemical correlate of the human disease cystinosis. These studies indicate that cystine dimethylester can induce an experimental form of the Fanconi syndrome both in vivo and in vitro and offers a new model for investigating the mechanisms underlying this enigmatic disorder.
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Affiliation(s)
- J W Foreman
- Division of Biochemical Development and Molecular Diseases, Children's Hospital of Philadelphia, PA 19104
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Bowring MA, Foreman JW, Lee J, Segal S. Characteristics of lysine transport by isolated rat renal cortical tubule fragments. Biochim Biophys Acta 1987; 901:23-9. [PMID: 3109479 DOI: 10.1016/0005-2736(87)90252-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The uptake of L-lysine was examined in isolated renal cortical tubules. Lysine was actively taken up by the renal tubule cells isolated from 7-week-old rats. No metabolism of the transported lysine was found. There was no evidence for sodium-dependence of lysine uptake. Concentration dependence studies revealed that the lysine was taken up by one saturable transport system with a Km of 1.66 mmol/l and Vmax of 7 mmol/l intracellular fluid per 10 min. Lysine also entered by a non-saturable pathway. Arginine and ornithine inhibited the initial uptake of lysine. Cystine increased the efflux of lysine from preloaded renal cells via hetero-exchange, indicating that a common system exists for these two amino acids.
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Foreman JW, McNamara PD, Bowring MA, Lee J, Rea C, Segal S. Cystine-glutamate transport interactions in rat renal cortical tubules, brushborder vesicles, and cultured renal tubule cells. Biosci Rep 1986; 6:113-9. [PMID: 2870746 DOI: 10.1007/bf01145186] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Glutamate had no significant effect on the uptake of 0.025 mM cystine by isolated rat renal cortical tubules and brushborder membrane vesicles in contrast to lysine which significantly inhibits cystine transport. Glutamate, however, markedly inhibited cystine uptake by rat renal tubule cells grown in a serum-free, hormonally defined media for 5 days. Lysine also inhibited cystine transport in these cultured renal tubule cells.
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Abstract
The Ia (immune-associated, DR) antigen is a cell surface glycoprotein which is absent on normal circulating T lymphocytes but present on activated T lymphocytes. We studied the expression of this antigen on circulating T lymphocytes from patients with untreated hyperthyroid Graves' disease. All patients (n = 33) with recent onset hyperthyroid Graves' disease studied had an increased percentage and number of circulating Ia+ T cells. Patients with non-Graves's hyperthyroidism or Graves' disease patients more than 1 yr after thyroid ablation had normal values for Ia+ T cells. Other cell surface activation antigens, recognized by monoclonal antibodies 4F2 and 5E9, were not present on circulating T cells in patients with Graves' disease. The 100% positivity for increased numbers of Ia antigen-bearing T cells in hyperthyroid Graves' disease contrasts with our finding of 70% positivity in another HLA-DR-associated disease, recent onset type I diabetes mellitus. The pathogenic significance of these cells is not known, but they seem to represent selective activation of the immune system in patients with untreated hyperthyroid Graves' disease.
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Eisenbarth GS, Shimizu K, Bowring MA, Wells S. Expression of receptors for tetanus toxin and monoclonal antibody A2B5 by pancreatic islet cells. Proc Natl Acad Sci U S A 1982; 79:5066-70. [PMID: 6750614 PMCID: PMC346828 DOI: 10.1073/pnas.79.16.5066] [Citation(s) in RCA: 79] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Studies of the reaction of antibody A2B5 and tetanus toxin with pancreatic islet cells, islet cell tumors, and other human amine precursor uptake and decarboxylation (APUD) tumors are described. By indirect immunofluorescence, antibody A2B5 and tetanus toxin were shown to specifically bind to the plasma membrane of human, rat, chicken, and mouse islet cells. The binding of antibody A2B5 to the cell surface of living islet cells has allowed isolation of these cells from a suspension of pancreatic cells by using a fluorescence-activated cell sorter. In studies designed to determine whether tetanus toxin and antibody A2B5 bound to the same surface antigen, A2B5 and tetanus toxin did not compete for binding to normal islet cells, a human islet cell tumor, or a rat islet cell tumor. In addition to binding to islet cell tumors, antibody A2B5 reacts with frozen sections, isolated cells, and cell lines of neural, neural crest, and APUD origin.
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