Synthesis of 2-(5-nitropyrid-2-yl)-3-(4-substitutedphenyl)aminoisoxazol- 5(2h)-ones and their rearrangements to imidazo[1,2-a]-pyridines and indoles with triethylamine

Abstract

3-(4-Substitutedphenyl)aminoisoxazol-5(2H)-ones, substituted on nitrogen with a nitropyridine group, react with triethylamine to give imidazo[1,2-a]pyridines and indoles. With 4-bromophenyl and 4-methylphenyl group substituents only imidazopyridines are formed, but the 4-methoxyphenyl derivative gave a 3:1 mixture of the corresponding imidazo[1,2-a]pyridine and 2-pyridylaminoindole, respectively.