Difluorinated compounds as depigmenting or lightening agents

A compound having the following formula I:

• or a cosmetically or pharmaceutically acceptable salt thereof, a stereoisomer or a mixture of stereoisomers in any proportion,
• wherein:
• R1 represents a hydrogen atom, OH, OSiR3R4R5, OR6, OC(O)R7, OCO2R8, OC(O)NR9R10, OP(O)(OR11)2, or OSO3R12,
• R2 represents OH, OSiR13R14R15, OR16, OC(O)R17, OCO2R18, OC(O)NR19R20, OP(O)(OR21)2, OSO3R22, NH2, NHR33, or NR33R34,
• X1, X2, X3, X4 and X5 represent, independently from one another, a hydrogen atom, OH, OSiR23R24R25, OR26, OC(O)R27, OCO2R28, OC(O)NR29R30, OP(O)(OR31)2, or OSO3R32, with:
• R3, R4, R5, R13, R14, R15, R23, R24 and R25 representing, independently from one another, a (C1-C6)alkyl, aryl, aryl-(C1-C6)alkyl or (C1-C6)alkyl-aryl group,
• R6, R16 and R26 representing, independently from one another, a O-protecting group;
• or a (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, (C3-C7)cycloalkyl, 5- to 7-membered heterocycloalkyl, aryl, heteroaryl, (C3-C7)cycloalkyl-(C1-C6)alkyl, (5- to 7-membered heterocycloalkyl)-(C1-C6)alkyl, aryl-(C1-C6)alkyl or heteroaryl-(C1-C6)alkyl group, said group being optionally substituted by one or several groups selected from a halogen atom, a (C1-C6)alkyl group and a (C1-C6)alkoxy group,
• R7, R8, R17, R18, R27 and R28 representing, independently from one another, a (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, (C3-C7)cycloalkyl, 5- to 7-membered heterocycloalkyl, aryl, heteroaryl, (C3-C7)cycloalkyl-(C1-C6)alkyl, (5- to 7-membered heterocycloalkyl)-(C1-C6)alkyl, aryl-(C1-C6)alkyl or heteroaryl-(C1-C6)alkyl group, said group being optionally substituted by one or several groups selected from a halogen atom, a (C1-C6)alkyl group and a (C1-C6)alkoxy group,
• R9, R10, R19, R20, R29 and R30 representing, independently from one another, a hydrogen atom;
• a N-protecting group;
• or a (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, (C3-C7)cycloalkyl, 5- to 7-membered heterocycloalkyl, aryl, heteroaryl, (C3-C7)cycloalkyl-(C1-C6)alkyl, (5- to 7-membered heterocycloalkyl)-(C1-C6)alkyl, aryl-(C1-C6)alkyl or heteroaryl-(C1-C6)alkyl group, said group being optionally substituted by one or several groups selected from a halogen atom, a (C1-C6)alkyl group and a (C1-C6)alkoxy group,
• R11, R12, R21, R22, R31 and R32 representing, independently from one another, a hydrogen atom or a (C1-C6)alkyl group, and
• R33 and R34 representing, independently from one another, a N-protecting group;
• or a (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, (C3-C7)cycloalkyl, 5- to 7-membered heterocycloalkyl, aryl, heteroaryl, aryl-(C1-C6)alkyl, heteroaryl-(C1-C6)alkyl, (C1-C6)-alkyl-aryl or (C1-C6)-alkyl-heteroaryl group, said group being optionally substituted by one or several groups selected from a halogen atom, OH, COOH and CHO.