Photooxidation of N,N′-Diacylindigo Dyes
Irradiation of N,N′-diacylindigo dyes in the presence of oxygen resulted in an unusual oxygen insertion/acyl transfer reaction. While this process occurred over many weeks at room temperature, at 100° C it was complete in a few hours. In some cases the yield of photooxidized product was virtually quantitative. The product structures were proved by spectroscopic methods and in one example by X-ray analysis. A series of mechanistic experiments led to the conclusion that at least the oxygen insertion part of the photooxidation process proceeded via a radical mechanism. The evidence included the following observations: (1) When the photooxidation was conducted in toluene, large amounts of benzyl hydroperoxide were produced; (2) the photooxidation could be achieved in the dark with a radical initiator; (3) attempts to generate the photooxidized product using singlet oxygen chemistry failed. The postulated radical mechanism is described. © 1994, American Chemical Society. All rights reserved.
Journal of Organic Chemistry
Chemistry and Biochemistry
Smith, Bradley D.; Alonso, David E.; Bien, Jeffrey T.; Metzler, Elise C.; Shang, Maoyu; and Roosenberg, John M. II, "Photooxidation of N,N′-Diacylindigo Dyes" (1994). Faculty Publications. 2562.