Acetic Anhydride → 7-(1-Ethyl-2-methyl-3-indolyl)-7-(diphenylamino)furo[3,4-b]pyridine

Participants

Reaction Steps

A mixture containing 4.5 g. of an isomer mixture comprising 2-[(1-ethyl-2-methyl-3-indolyl)carbonyl]-3-pyridinecarboxylic acid and 3-[(1-ethyl-2-methyl-3-indolyl)carbonyl]-2-pyridinecarboxylic acid, 2.5 g. of diphenylamine and 30 ml. of acetic anhydride was stirred 6.5 hours, then treated with one ml. of pyridine and allowed to stand overnight. The reaction mixture was poured into 750 ml. of water and the resulting solid product was purified by column chromatography affording 7-(1-ethyl-2-methyl-3-indolyl)-7-(diphenylamino)furo[3,4-b]pyridine-(5(7H)-one as a light orange solid, m.p. 132.5°-136° C. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

Provenance & Evidence