Developing Photoactive Coumarin-Caged N-Hydroxysulfonamides for Generation of Nitroxyl (HNO)
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Abstract
Photoactive N-hydroxysulfonamides photocaged with the (6-bromo-7-hydroxycoumarin-4-yl)methyl chromophore have been successfully synthesized, and the mechanisms of photodecomposition investigated for two of the compounds. Upon irradiation up to 97% of a diagnostic marker for (H)NO release, sulfinate was observed for the trifluoromethanesulfonamide system. In the absence of a species that reacts rapidly with (H)NO, (H)NO instead reacts with the carbocation intermediate to ultimately generate (E)-BHC-oxime and (Z)-BHC-oxime. Alternatively, the carbocation intermediate reacts with solvent water to give a diol. Deprotonation of the N(H) proton is required for HNO generation via concerted C-O/N-S bond cleavage, whereas the protonation state of the O(H) does not affect the observed photoproducts. If the N(H) is protonated, C-O bond cleavage to generate the parent N-hydroxysulfonamide will occur, and/or O-N bond cleavage to generate a sulfonamide. The undesired competing O-N bond cleavage pathway increases when the volume percentage of water in acetonitrile/water solvent mixtures is increased.Description
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HNO, N-hydroxysulfonamide, Piloty’s acid, nitroxyl, photocage, photochemistry, 3402 Inorganic Chemistry, 34 Chemical Sciences, 0304 Medicinal and Biomolecular Chemistry, 0305 Organic Chemistry, 0307 Theoretical and Computational Chemistry, Organic Chemistry, 3404 Medicinal and biomolecular chemistry, 3405 Organic chemistry
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Molecules, ISSN: 1420-3049 (Print); 1420-3049 (Online), MDPI AG, 29(16), 3918-. doi: 10.3390/molecules29163918
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© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).