13 g (0.03 mol) of the 2,4,5-tris(4'-nitrophenyl)oxazole was mixed with 500 ml of N,N-dimethylformamide and 26 g of iron powder. The mixture thus obtained was admixed with 10 ml of concentrated sulfuric acid and 30 ml of water, and then heated to a temperature of 100° C. with stirring. After 1 hour passed, the mixture was neutralized with a saturated aqueous solution of sodium bicarbonate with the reaction temperature kept at a temperature of 100° C. The pH of the solution after the reaction was adjusted to 8. The reaction solution was hot-filtered, and the filtrate was then poured into 3 l of ice water to produce a light yellow precipitate of 2,4,5-tris(4'-aminophenyl)oxazole which was then filtered off and dried to obtain 4.47 g of the product (yield: 97%).
