Coupling of P2Y1 receptor antagonists to PAMAM dendrimers in a manner that preserves the interaction with the receptor. (A) Attempted use of the Sonogashira reaction to couple a 2-iodoadenine derivative to a terminal alkyne G3 dendrimer. Reagents and conditions: (i) HATU, 4-pentynoic acid, DIEA, DMF (ii) CuI, (Ph3P)2PdCl2,TEA, DMF, rt. (B) Attempted coupling of a 2-amine derivatized nucleotide to a terminal carboxylic acid G2.5 dendrimer. Reagents: (i) Compound 30, HATU, DIEA, DMSO. (C) Successful use of click chemistry to couple an alkyne-functionalized, protected nucleotide derivative to a terminal azido-bearing G4 dendrimer to yield dendrimer conjugate 53 (MRS2966). Reagents: (i) CuSO4 aq., sodium ascorbate; (ii) TFA.