Photolysis of NSAIDs. Part 3: Structural elucidation of photoproducts of tolmetin in methanol
Photolysis of tolmetin in methanol produces eight photoproducts via a novel α-cleavage of a ketone, decarboxylation, and oxidation. A sample of 10 mM tolmetin in methanol was photo-irradiated with a Hanovia 200 W high-pressure quartz Hg lamp for four days. In total, eight photoproducts were observed from the HPLC chromatogram. Three major photoproducts were separated, and their structures were elucidated by spectroscopic methods. The structures of all photoproducts were further determined by LC-ESI-MS. A reaction scheme of tolmetin was proposed.
Copper(II), in the parts per million range, modulates photochemical and photosensitizing properties of tolmetin via electron transfer with a triplet carbanion
Copper(II), at very low levels of concentration, modulates the distribution of tolmetin stable photoproducts as well as inhibits the DNA cleavage photoinduced by the drug, via a highly efficient electron transfer process with the main transient species generated in the tolmetin photolysis.
Sortino,Scaiano,De Guidi,Costanzo
p. 2003 - 2004
(2007/10/03)
Laser Flash Photolysis of Tolmetin: A Photoadiabatic Decarboxylation with a Triplet Carbanion as the Key Intermediate in the Photodecomposition
The transient photochemistry of tolmetin (TM), 5-(p-toluoyl)-1-methyl-2-pyrrolyacetic acid, a drug belonging to the nonsteroidal anti-inflammatory class, has been studied in aqueous solution by using nanosecond laser flash photolysis techniques. The photoreactivity of TM is characterized by an adiabatic pathway involving a triplet carbanion as the key intermediate in the photodecarboxylation. A short-lived triplet is proposed as the precursor of this transient species. A minor channel for laser photodecomposition involving photoionization has also been identified. This latter photoprocess occurs predominantly through a biphotonic mechanism.
Sortino,Scaiano
p. 167 - 172
(2007/10/03)
Acid-Mediated Rearrangement of Acylpyrroles
N-Alkyl-2-acylpyrroles are converted by strong anhydrous acid to 1-alkyl-3-acylpyrroles.An equilibrium mixture of 2- and 3-acylpyrrole is produced by treatment of a 2- or 3-acyl NH pyrrole with acid.Pyrrolecarboxaldehydes similarly afford isomeric mixtures.A cross-ring migration, 7->8, is observed when the adjacent position is blocked.The mechanism of acid-mediated rearrangement of acylpyrroles is discussed.
Carson, John R.,Davis, Nancy M.
p. 839 - 843
(2007/10/02)
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