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Updated: Jun 14, 2025

Design, Synthesis, and Photochemical Properties of Clickable Caged Compounds
Published on: October 15, 2019
Developing Photoactive Coumarin-Caged N-Hydroxysulfonamides for Generation of Nitroxyl (HNO)
Mohammad S Rahman1, Vinay Bharadwaj2,3, Anau K H S Lautaha2,3
1Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA.
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.
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