Compounds of the formula ##STR1## in which R.sub.1 and R.sub.2 are unsubstituted or substituted phenyl or naphthyl, and R.sub.3 and R.sub.4 are alkyl, alkoxycarbonyl, phenyl, benzoyl or benszl, are suitable for dyeing high molecular weight organic material.
式子##STR1##中,R.sub.1和R.sub.2为未取代或取代的苯基或
萘基,R.sub.3和R.sub.4为烷基,烷氧羰基,苯基,苯甲酰基或苯基甲酰基,适用于染色高分子量有机材料。