Example 18
To a stirred solution of compound 13 (21.8 mg) in anhydrous DMF (500 μL) was added NMM (7.8 μL). This solution was then added dropwise over a period of 20 min to a stirred solution of suberic acid bis(N-hydroxysuccinimide ester) (43.8 mg) in anhydrous DMF (1.5 mL) at room temperature under an argon atmosphere. The reaction mixture was then stirred at room temperature for 20 h before the solution was concentrated in vacuo and purified by reverse phase C18-column chromatography, eluting with buffer A (v/v): water:0.05% trifluoroacetic acid and buffer B (v/v): acetonitrile:0.05% trifluoroacetic acid (90:10 v/v to 0:100 v/v). The organic solvent was removed in vacuo and the aqueous solvent removed by lyophilisation to give reagent 48 as a white solid (15.2 mg). m/z [M+Na]+ (2126, 10%), [M+H]+ (2104, 20%), [M+2Na]2+ (1074, 50%), [M+Na+H]2+ (1063, 50%) [M+2H]2+ (1052, 100%).
