Peculiarities of the Reaction of 2-Amino-1,4-naphthoquinones with 2,2-Dihydroxy-1H-indene-1,3(2H)-dione

Abstract

—The reaction of 2-amino-1,4-naphthoquinones with ninhydrin at 50–60°C in acetic acid leads to 4b,11b-dihydroxy-4b,5-dihydrobenzo[f]indeno[1,2-b]indole-6,11,12(11bH)-triones. The products were isolated as hydrates, and, when heated in DMSO with methanesulfonic acid or in acetic acid in the presence of sulfuric acid, they converted into 13-R-benzo[f]isochromeno[4,3-b]indole-5,7,12(13H)-triones. The rate of the conversion of 4b,11b-dihydroxy-4b,5-dihydrobenzo[f]indeno[1,2-b]indole-6,11,12(11bH)-triones to 13-R-benzo[f]isochromeno[4,3-b]indole-5,7,12(13H)-triones in solutions of sulfuric acid in acetic acid is linearly related to the Hammett acidity function.