2-(4-Aminophenylamino)-2-oxoacetic acid diazo, and 5-Aminonaphthalene-2-sulfonic acidcoupling, again diazo, and 5-Aminonaphthalene-2-sulfonic acidcoupling, product to diazo, and 6-Hydroxynaphthalene-2-sulfonic acidand where did 4-Hydroxynaphthalene-1-sulfonic acidcoupling, and then 2-(4-Aminophenylamino)-2-oxoacetic acid hydrolysis base.
