Use of a compound of the formula (1a) ** Formula ** wherein R2 is hydrogen； C1-C22 alkyl； C3-C8 cyclo-alkyl； unsubstituted or C1-C6- alkyl or C6-C20 aryl substituted with C1-C6 alkoxy； or a cyano group； R4 is a cyano group； or -Q1-R5； Q1 is -COO-； -CONH-； -CO-； -SO2-； or -CONR6-； R5 is C1-C22 alkyl； C3-C8 cyclo-alkyl； or unsubstituted or C6-C20 aryl substituted with C1-C8 alkyl； R6 is hydrogen； C1-C22 alkyl； C3-C8 cyclo-alkyl； unsubstituted or C1-C6 alkyl or C6-C20 aryl substituted with C1-C6 alkoxy； the cyclohexene C radical is unsubstituted or substituted by one or more C1-C5 alkyl； n is from 2 to 4； if n>； = 2, in the formula (1a) R 1 is an alkylene radical, or cycloalkylene； or R1 and R2 together with the nitrogen atom attached thereto simultaneously form a bivalent radical of the formula ** Formula ** and R3 is a cyano group or -Q1-R5； or R3 and R4 together form a monocyclic carbocyclic ring of 5 to 7 members, which is optionally interrupted by -O- or -NR7-； if n>； = 3, in the formula (1a). R1 is a trivalent alkyl group； and R3 is a cyano group or -Q1-R5； or R3 and R4 together form a monocyclic carbocyclic ring of 5 to 7 members； if n>； = 4, in formula (1a) R1 is a tetravalent alkyl group； and R3 is a cyano group； or -Q1-R5: or R3 and R4 together form a monocyclic carbocyclic ring of 5 to 7 members； in the manufacture of a product to protect human or animal hair and skin from UV radiation.Uso de un compuesto de la fórmula (1a)**Fórmula** en donde R2 es hidrógeno； alquilo C1-C22； ciclo-alquilo C3-C8； no sustituido o alquilo C1-C6- o arilo C6-C20 sustituido con alcoxi C1-C6； o un grupo ciano； R4 es un grupo ciano； o -Q1-R5； Q1 es -COO-； -CONH-； -CO-； -SO2-； o -CONR6-； R5 es alquilo C1-C22； ciclo-alquilo C3-C8； o no sustituido o arilo C6-C20 sustituido con alquilo C1-C8； R6 es hidrógeno； alquilo C1-C22； ciclo-alquilo C3-C8； no sustituido o alquilo C1-C6 o arilo C6-C20 sustituido con alcoxi C1-C6； el radical ciclohexeno C es no sustituido o sustituido por uno
