Photochemical and photophysical behavior of indolyl anions in photostimulated intramolecular arylation reactions

JUAN E. ARGÜELLO; VICTORIA A. VAILLARD; ROBERTO A. ROSSI

Córdoba

Encuentro; XI Encuentro Latinoamericano de Fotoquímica y Fotobiología ? ELAFOT; 2012

Recently we have reported an efficient strategy to afford a family of 2-pyrrolyl and 2-indolyl benzoxazole by a photostimulated intramolecular O-arylation reactions. With the aim of studying the mechanism of these reactions, we studied anions from 2-haloindolylbenzamides, which leads to the formation of indolylbenzoxazole. We found that the reaction does not occur in the dark and is inhibited partially by the addition of good electron acceptors. Competition studies showed that the bromo derivative was 1.6 times more reactive than the chloro derivative. Moreover, the reaction happen when we used a base non-electron donor as NaH. By fluorescence and time- resolved fluorescence measurements we determined that the fluorescence quantum yields (Qf) and fluorescence lifetimes (tf) depends of the presence and nature of halogen in the molecule (H>Cl>Br). When we used the anion from indolylbenzamide in quenching experiments with halobenzenes, we find that the quenching is dynamic and followed the order PhI-PhBr-PhCl