Isolation of Cross-Coupling Products in Model Studies on the Photochemical Modification of Proteins by Tiaprofenic Acid

Photoreaction between 2-Benzoylthiophene and Phenol or Indole

“…Analysis of the isolated pinacols by 1 H NMR allowed a reliable structure assignment by comparison with the data reported for analogous compounds (Et-BT pinacol diastereoisomers). 17 On the other hand, the spectral data agreed with structures 3, 4, and 5 36 the cross-coupling with M +. 282, 264, and 266, respectively (Scheme 3).…”

“…Irradiation of a deaerated acetonitrile solution of benzoylthiophene and phenol, using the Pyrex-filtered light from a medium-pressure mercury lamp, led to a complex mixture containing the known pinacols 1 35 along with minor amounts of pinacolone 2 (from rearrangement of the pinacols)35b and cross-coupling products with M +• 264, 266, and 282. Analysis of the isolated pinacols by 1 H NMR allowed a reliable structure assignment by comparison with the data reported for analogous compounds (Et-BT pinacol diastereoisomers) . On the other hand, the spectral data agreed with structures 3 , 4 , and 5 for the cross-coupling photoproducts with M +.…”

“…Related photochemical reactions of phenols with aromatic ketones have been previously studied. ,37b Thus, photolysis of aromatic ketones in the presence of 2,6-disubstituted phenols, followed by coupling of the generated ketyl and phenoxy radicals and tautomerization gives rise to triaryl carbinols. These carbinols are converted into 3,5-disubstituted fuchsones in a nonphotochemical process.…”

Photoreaction Between Benzoylthiophenes and N-BOC-Tryptophan Methyl Ester‡

“…Similar experiments were performed using TPA methyl ester (5) ( 1c ). In this case, GC/MS analysis of the complex mixture also showed formation of pinacols 12 , together with Trp homodimers and lactones 13 (Scheme 4).…”

Photosensitization by drugs

“…Formation of (D)TPA/phenol cross-coupling products and phenol dimers [18] suggests the possibility that, besides photodegradation of amino acid units, other chemical modifications of proteins such as drug/protein photobinding and protein photocrosslinking (through coupling ot two Tyr units) can occur. This has been confirmed by irradiation of BSA with radiolabeled (D)TPA.…”