Synthesis of 6-Substituted 2-Pyrrolyl and Indolyl Benzoxazoles by Intramolecular O-Arylation in Photostimulated Reactions

VAILLARD, V. A.; GUASTAVINO, J. F.; BUDÉN, M. E.; BARDAGÍ, J. I.; BAROLO, S. M.; ROSSI, R. A.

JOURNAL OF ORGANIC CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 77 p. 1507 - 1519

0022-3263

The synthesis of a series of 6-substituted 2-pyrrolyl and 2-indolyl benzoxazoles by photostimulated C-O cyclization of anions from 2-pyrrole carboxamides, 2-indolo carboxamides or 3-indolo carboxamides has been found to proceed in good to excellent yields (41-100%) in DMSO and in liquid ammonia. The pyrrolo and indolo carboxamides are obtained in good to very good isolated yields by an amidation reaction of different 2-haloanilines with 2-carboxylic acid of pyrrole and 2- or 3-carboxylic acid of indole. In order to explain the surprising regiochemical outcome of these reactions (C-O arylation vs C-N or C-C arylation), a theoretical analysis was performed with DFT methods and the B3LYP functional.