Methyl 4-azidobutyrate (200 mg, 1.40 mmol) and 1-ethynyl-4-methoxybenzene (277 mg, 210 mmol) were dissolved in dioxane (3 mL) and heated in a microwave reactor for 5 min at 175° C. The reaction mixture was filtered and the filtrate was concentrated under vacuum. Compound 3-[4-(4-methoxy-phenyl)-[1,2,3]triazol-1-yl]-propionic acid methyl ester was treated with aqueous 2M NaOH (5 mL) in THF (3 mL) and stirred at RT for 5 h. The methanol was removed under vacuum and the residue was dissolved in dioxane (5 mL) and treated with concentrated HCl dropwise until a precipitate formed. The resulting acid was collected by filtration and the purity was measured by RPLC (78%). Compound 3-[4-(4-methoxy-phenyl)-[1,2,3]triazol-1-yl]-propionic acid (125 mg, 0.50 mmol) and 4-(3-amino-propylamino)-2H-phthalazin-1-one (100 mg, 0.46 mmol) were dissolved in DMF (2 mL) and treated with EDC (95 mg, 0.50 mmol) and triethylamine (76 mg, 0.75 mmol). 3-[4-(4-Methoxy-phenyl)-[1,2,3]triazol-1-yl]-N-[3-(4-oxo-3,4-dihydro-phthalazin-1-ylamino)-propyl]-propionamide was isolated by preparative RPLC.
