Phosgene → HCID 69131963, compound

Participants

Reaction Steps

To a phosgene solution (20% solution in toluene) at 0° C. was added piperazine-1-carboxylic acid benzyl ester (0.385 mL, 1.996 mmol) and diisopropylethyl amine (0.383 mL, 4.397 mmol) in 5 mL of CH2Cl2 dropwise. The resulting pale yellow mixture was stirred 2 h warming to room temperature under Ar. The phosgene solution was removed by vacuum distillation. 20 mL of anhydrous CH2Cl2 was added. The reaction vessel was cooled to 0° C. and hydrazinecarboxylic acid tert-butyl ester and diisopropylethyl amine (0.383 mL, 4.397 mmol) was added in one portion. The reaction was warmed to room temperature and stirred for 1 h. The reaction was quenched with 10 mL of saturated NaHCO3, diluted with 30 mL of EtOAc, then washed with 2×30 mnL of saturated NH4Cl solution and 30 mL of brine. The organic phase was dried over MgSO4, filtered and concentrated to provide 720 mg of 4-(N-tert-butoxycarbonyl-hydrazinocarbonyl)-piperazine-1-carboxylic acid benzyl ester as a white solid.

Provenance & Evidence