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Bharadwaj V, Rahman MS, Sampson P, Seed AJ, Brasch NE. Exploring the Potential of 2-(2-Nitrophenyl)ethyl-Caged N-Hydroxysulfonamides for the Photoactivated Release of Nitroxyl (HNO). J Org Chem 2021; 86:16448-16463. [PMID: 34797664 DOI: 10.1021/acs.joc.1c01800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The emergence of nitroxyl (HNO) as a biological signaling molecule is attracting increasing attention. HNO-based prodrugs show considerable potential in treating congestive heart failure, with HNO reacting rapidly with metal centers and protein-bound and free thiols. A new class of 2-(2-nitrophenyl)ethyl (2-NPE)-photocaged N-hydroxysulfonamides has been developed, and the mechanisms of photodecomposition have been investigated. Three photodecomposition pathways are observed: the desired concomitant C-O/N-S bond cleavage to generate HNO, sulfinate, and 2-nitrostyrene, C-O bond cleavage to give the parent sulfohydroxamic acid and 2-nitrostyrene, and O-N bond cleavage to release a sulfonamide and 2-nitrophenylacetaldehyde. Laser flash photolysis experiments provide support for a Norrish type II mechanism involving 1,5-hydrogen atom abstraction to generate an aci-nitro species. A mechanism is proposed in which the (Z)-aci-nitro intermediate undergoes either C-O bond cleavage to release RSO2NHO(H), concerted C-O/N-S bond cleavage to generate sulfinate and HNO, or isomerization to the (E)-isomer prior to O-N bond cleavage. The pKa of the N(H) of the N-hydroxysulfonamide plays a key role in determining whether C-O or concerted C-O/N-S bond cleavage occurs. Deprotonating this site favors the desired C-O/N-S bond cleavage at the expense of an increased level of undesired O-N bond cleavage. Triplet state quenchers have no effect on the observed photoproducts.
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Affiliation(s)
- Vinay Bharadwaj
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.,The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand
| | - Mohammad S Rahman
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Paul Sampson
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Alexander J Seed
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Nicola E Brasch
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.,The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand.,The Maurice Wilkins Centre for Molecular Biodiscovery, Private Bag 92019, Auckland 1142, New Zealand
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2
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Gallego CM, Mazzeo A, Vargas P, Suárez S, Pellegrino J, Doctorovich F. Azanone (HNO): generation, stabilization and detection. Chem Sci 2021; 12:10410-10425. [PMID: 34447533 PMCID: PMC8356739 DOI: 10.1039/d1sc02236a] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 07/05/2021] [Indexed: 12/14/2022] Open
Abstract
HNO (nitroxyl, azanone), joined the 'biologically relevant reactive nitrogen species' family in the 2000s. Azanone is impossible to store due to its high reactivity and inherent low stability. Consequently, its chemistry and effects are studied using donor compounds, which release this molecule in solution and in the gas phase upon stimulation. Researchers have also tried to stabilize this elusive species and its conjugate base by coordination to metal centers using several ligands, like metalloporphyrins and pincer ligands. Given HNO's high reactivity and short lifetime, several different strategies have been proposed for its detection in chemical and biological systems, such as colorimetric methods, EPR, HPLC, mass spectrometry, fluorescent probes, and electrochemical analysis. These approaches are described and critically compared. Finally, in the last ten years, several advances regarding the possibility of endogenous HNO generation were made; some of them are also revised in the present work.
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Affiliation(s)
- Cecilia Mariel Gallego
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Agostina Mazzeo
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Paola Vargas
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Sebastián Suárez
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Juan Pellegrino
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Fabio Doctorovich
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
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Cink RB, Zhou Y, Du L, Rahman MS, Phillips DL, Simpson MC, Seed AJ, Sampson P, Brasch NE. Mechanistic Insights into Rapid Generation of Nitroxyl from a Photocaged N-Hydroxysulfonamide Incorporating the (6-Hydroxynaphthalen-2-yl)methyl Chromophore. J Org Chem 2021; 86:8056-8068. [PMID: 34107217 DOI: 10.1021/acs.joc.1c00457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
HNO is a highly reactive molecule that shows promise in treating heart failure. Molecules that rapidly release HNO with precise spatial and temporal control are needed to investigate the biology of this signaling molecule. (Hydroxynaphthalen-2-yl)methyl-photocaged N-hydroxysulfonamides are a new class of photoactive HNO generators. Recently, it was shown that a (6-hydroxynaphthalen-2-yl)methyl (6,2-HNM)-photocaged derivative of N-hydroxysulfonamide incorporating the trifluoromethanesulfonamidoxy group (1) quantitatively generates HNO. Mechanistic studies have now been carried out on this system and reveal that the ground state protonation state plays a key role in whether concerted heterolytic C-O/N-S bond cleavage to release HNO occurs versus undesired O-N bond cleavage. N-Deprotonation of 1 can be achieved by adding an aqueous buffer or a carboxylate salt to an aprotic solvent. Evidence is presented for C-O/N-S bond heterolysis occurring directly from the singlet excited state of the N-deprotonated parent molecule on the picosecond time scale, using femtosecond time-resolved transient absorption spectroscopy, to give a carbocation and 1NO-. This is consistent with the observation of significant fluorescence quenching when HNO is generated. The carbocation intermediate reacts rapidly with nucleophiles including water, MeOH, or even (H)NO in the absence of a molecule that reacts rapidly with (H)NO to give an oxime.
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Affiliation(s)
- Ruth B Cink
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.,The Photon Factory, School of Chemical Sciences and Department of Physics, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6012, New Zealand.,The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand
| | - Yang Zhou
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Lili Du
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR 99077, P. R. China
| | - Mohammad S Rahman
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR 99077, P. R. China
| | - M Cather Simpson
- The Photon Factory, School of Chemical Sciences and Department of Physics, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6012, New Zealand.,The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand
| | - Alexander J Seed
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Paul Sampson
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Nicola E Brasch
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.,The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand.,The Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
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Confer AM, Vilbert AC, Dey A, Lancaster KM, Goldberg DP. A Mononuclear, Nonheme Fe II-Piloty's Acid (PhSO 2NHOH) Adduct: An Intermediate in the Production of {FeNO} 7/8 Complexes from Piloty's Acid. J Am Chem Soc 2019; 141:7046-7055. [PMID: 30994347 DOI: 10.1021/jacs.9b01700] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Reaction of the mononuclear nonheme complex [FeII(CH3CN)(N3PyS)]BF4 (1) with an HNO donor, Piloty's acid (PhSO2NHOH, P.A.), at low temperature affords a high-spin ( S = 2) FeII-P.A. intermediate (2), characterized by 57Fe Mössbauer and Fe K-edge X-ray absorption (XAS) spectroscopies, with interpretation of both supported by DFT calculations. The combined methods indicate that P.A. anion binds as the N-deprotonated tautomer (PhSO2NOH-) to [FeII(N3PyS)]+, leading to 2. Complex 2 is the first spectroscopically characterized example, to our knowledge, of P.A. anion bound to a redox-active metal center. Warming of 2 above -60 °C yields the stable {FeNO}7 complex [Fe(NO)(N3PyS)]BF4 (4), as evidenced by 1H NMR, ATR-IR, and Mössbauer spectroscopies. Isotope labeling experiments with 15N-labeled P.A. confirm that the nitrosyl ligand in 4 derives from P.A. In contrast, addition of a second equivalent of a strong base leads to S-N cleavage and production of an {FeNO}8 species, the deprotonated analog of an Fe-HNO complex. This work has implications for the targeted delivery of HNO/NO-/NO· to nonheme Fe centers in biological and synthetic applications, and suggests a new role for nonheme FeII complexes in the assisted degradation of HNO donor molecules.
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Affiliation(s)
- Alex M Confer
- Department of Chemistry , The Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Avery C Vilbert
- Baker Laboratory, Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Aniruddha Dey
- Department of Chemistry , The Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Kyle M Lancaster
- Baker Laboratory, Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - David P Goldberg
- Department of Chemistry , The Johns Hopkins University , Baltimore , Maryland 21218 , United States
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Zhou Y, Cink RB, Seed AJ, Simpson MC, Sampson P, Brasch NE. Stoichiometric Nitroxyl Photorelease Using the (6-Hydroxy-2-naphthalenyl)methyl Phototrigger. Org Lett 2019; 21:1054-1057. [PMID: 30694069 DOI: 10.1021/acs.orglett.8b04099] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The design and synthesis of a photoactivatable HNO donor incorporating the (6-hydroxynaphthalen-2-yl)methyl (6,2-HNM) photocage coupled to the trifluoromethanesulfonamidoxy analogue of the well-established HNO generator Piloty's acid is described. The photoactive HNO donor stoichiometrically generates HNO (∼98%) at neutral pH conditions, and evidence for concerted C-O and N-S bond cleavage was obtained. The methanesulfonamidoxy analogue primarily undergoes undesired N-O bond cleavage.
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Affiliation(s)
- Yang Zhou
- Department of Chemistry and Biochemistry , Kent State University , Kent , Ohio 44242 , United States
| | - Ruth B Cink
- School of Science , Auckland University of Technology , Auckland 1142 , New Zealand.,Dodd-Walls Centre for Quantum and Photonic Technologies , Dunedin 9054 , New Zealand.,The Photon Factory, School of Chemical Sciences , The University of Auckland , Auckland 1142 , New Zealand
| | - Alexander J Seed
- Department of Chemistry and Biochemistry , Kent State University , Kent , Ohio 44242 , United States
| | - M Cather Simpson
- Dodd-Walls Centre for Quantum and Photonic Technologies , Dunedin 9054 , New Zealand.,The Photon Factory, School of Chemical Sciences , The University of Auckland , Auckland 1142 , New Zealand.,The Department of Physics , The University of Auckland, The MacDiarmid Institute for Advanced Materials and Nanotechnology , Auckland 1142 , New Zealand
| | - Paul Sampson
- Department of Chemistry and Biochemistry , Kent State University , Kent , Ohio 44242 , United States
| | - Nicola E Brasch
- School of Science , Auckland University of Technology , Auckland 1142 , New Zealand.,Dodd-Walls Centre for Quantum and Photonic Technologies , Dunedin 9054 , New Zealand
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