The invention relates to compounds of formula (I): wherein R1, R2, and n are defined in the detailed description and claims. In particular, the present invention relates to the compounds of formula (I) for use in the manufacture and delivery of conjugated moieties such as small molecules, peptides, nucleic acids, fluorescent moieties, and polymers which are linked to alpha-V-beta-integrin antagonists to target cells expressing alpha-V-beta-3.