The mixture of (2E)-3-pentyl-3,7-dihydro-1H-purine-2,6-dione 2-hydrazone (0.50 g, 0.0021 mol), N-carbobenzyloxyglycine (0.49 g, 0.0023 mol), benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate (1.0 g, 2.3 mmol) and triethylamine (0.59 mL, 0.0042 mol) in DMF (20 mL) was stirred at room temperature overnight. The reaction mixture was diluted with EtOAc and washed with water (4×) and brine (1×). The aqueous was extracted with EtOAc (2×). The combined organic layers were dried (MgSO4) and concentrated to give the desired product (1.30 g, 86%). LCMS calculated for C20H26N7O4(M+H): 428.2; found 428.2.
