ethanol
water
sodium acetate
2,4,6-tribromo-benzenediazonium; chloride
ethyl acetoacetate
2-Hydroxy-4,5-diphenyl-6-(2,4,6-tribromo-phenyl)-5,6-dihydro-4H-pyrano[2,3-d]pyridazine-3,8-dicarboxylic acid diethyl ester
2-Amino-4,5-diphenyl-6-(2,4,6-tribromo-phenyl)-5,6-dihydro-4H-pyrano[2,3-d]pyridazine-3,8-dicarboxylic acid 8-ethyl ester
2,4,5-Triphenyl-6-(2,4,6-tribromo-phenyl)-5,6-dihydro-4H-pyrano[2,3-d]pyridazine-8-carboxylic acid ethyl ester
3-Acetyl-2-methyl-4,5-diphenyl-6-(2,4,6-tribromo-phenyl)-5,6-dihydro-4H-pyrano[2,3-d]pyridazine-8-carboxylic acid ethyl ester
2-Methyl-4,5-diphenyl-6-(2,4,6-tribromo-phenyl)-5,6-dihydro-4H-pyrano[2,3-d]pyridazine-8-carboxylic acid ethyl ester