The subject matter of the present invention is a compound characterized in that it has the general formula (I): in which P1, X, n, A, L and L1 are as defined in Claim 1. The present invention also relates to a process for preparing said compounds (I) and to the use thereof for targeting the cation-independent mannose 6-phosphate receptor (CI-M6PR). The subject matter of the invention is also a conjugate of formula (III): in which P1, X, n, A, L and L'1 are as defined in Claim 6, and the use thereof: - in a method for therapeutic treatment of the human or animal body, in particular chosen from enzyme replacement therapy, photodynamic therapy or cancer treatment, and/or - in a method of diagnosis, in particular of diseases or of ailments associated with an increase or with a decrease in CI-M6PR expression.
