The dyestuffs of the general formulae ##STR1## and salts thereof whereinX denotes hydrogen, alkoxy or NHR.sub.3,R denotes hydrogen, alkyl or alkoxy,R.sub.1 denotes alkyl,R.sub.2 and R.sub.3 denote hydrogen, alkyl, alkylcarbonyl, alkylsulphonyl, aryl, arylcar=bonyl, arylsulphonyl, aralkyl, aralkylcarbonyl or aminocarbonyl andm and n denote 1 or 2, andwherein the substituents mentioned can, in turn, be substituted by nonionic radicals or carboxylic or sulphonic acid groups customary in dyestuffs chemistry, are used for dyeing cellulose-containing materials and leather.