The Use, as a UV filter, of a compound of formula R1 and R2 are each independently of the other hydrogen; unsubstituted or halo-, amino-, mono- or di-C1-C5alkylamino-, cyano- or C1-C5alkoxy-substituted C1-C22alkyl, C5-C10cycloalkyl, carboxy-C1-C22alkyl, carboxy-C6-C10aryl, C6-C10aryl, C6-C10aryl-C1-C5alkyl; carbamoyl; or sulfamoyl; or R1 and R2, together with the nitrogen atom linking them, form a 5- to 7-membered heterocyclic radical; and R3 is hydrogen; or C1-C22alkyl; and R4 is hydrogen; hydroxy; C1-C22alkyl; or C1-C22alkoxy; is described. The compounds of formula (1) are suitable especially as UV filters in cosmetic preparations.