Bronsted acidic ionic liquids (BAILs), 2-pyrrolidonium hydrogen sulfate and (4-sulfobutyl)tris(4-sulfophenyl)phosphonium hydrogen sulfate are found to be efficient catalysts for synthesis of 14-aryl-14H-dibenzo[a,i]xanthene-8,13-dione, 3,4-dihydro-1H-benzo[b]xanthene-1,6,1 1(2H,12H)-trione, and aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone derivatives. (C) 2011 Elsevier B.V. All rights reserved.