1-Hydroxybenzotriazole → tert-Butyl methylcarbamate

Participants

Reaction Steps

To a solution of (S)-2-(tert-butoxycarbonyl-methyl-amino)-butyric acid (167 mg, 0.77 mmol) in DMF (5 mL) at room temperature, is added diisopropylethylamine (0.48 mL) slowly. After stirring at room temperature for 20 minutes, the solution is transferred to another flask contained (1S,9S)-9-amino-6,10-dioxo-octahydro-pyridazino[1,2-a][1,2]diazepine-1-carboxylic acid phenethyl-amide (240 mg, 0.70 mmol), and then a solution of HOBT (125 mg, 0.92 mmol) and HBTU (350 mg, 0.92 mmol) in DMF (5 mL) is added to the reaction mixture. After stirring for 1.5 hours, the reaction solution is diluted with ether (20 mL), and washed with water (2×10 mL). The combined organic layers is concentrated. The crude product is diluted with CH2Cl2 (10 mL) and dried over Na2SO4, and purified by chromatography (CH2Cl2/MeOH:97/3) to give (S)-1-((4S,7S)-6,10-dioxo-4-phenethylcarbamoyl-octahydro-pyridazino[1,2-a][1,2]diazepin-7-ylcarbamoyl)-propyl]-methyl-carbamic acid tert-butyl ester (270 mg, 71.3%) as pale solid. (NMR and MS data confirmed, U-3133-69).

Provenance & Evidence