Dibenzoylmethane compounds as photochemical precursors of ultraviolet absorbers

A compound of formula (I), a pharmaceutically or a cosmetically acceptable salt thereof, or a stereoisomer of any of them or mixtures thereof,

• or, alternatively,
• wherein:
• in compound (I),
• R′ is selected from the group consisting of H;
• (C1-C6)-alkyl, and (C3-C6)-cycloalkyl;
• R1, R2, R4, R5, R6, R7, R9, and R10 are a radical independently selected from the group consisting of H, hydroxy, amino, (C1-C6)-alkyl, (C1-C6)-alkoxy, (C1-C6)-alkylamino, and (C1-C6)-dialkylamino;
• R3 is (C1-C6)-alkyl;
• and
• R8 is selected form the group consisting of (C1-C6)-alkyl, (C1-C6)-alkoxy, hydroxy, amino, (C1-C6)-alkylamino, and (C1-C6)-dialkylamino;
• and
• in compound (I′),
• R1 and R6 are a radical independently selected from the group consisting of H, amino, (C1-C6)-alkyl, (C1-C6)-alkoxy, C1-C6)-alkylamino, and (C1-C6)-dialkylamino;
• R′, R2, R4, R5, R7, R9, R10 R3 and R3 are as defined in compound (I).