Hydrochloric Acid → Tert-butyl 4-[4-(4-{bis[(2,2,2-trichloroethoxy)carbonyl]amino}-1,2,5-oxadiazol-3-yl)phenyl]piperazine-1-carboxylate

Participants

Reaction Steps

To tert-butyl 4-[4-(4-amino-1,2,5-oxadiazol-3-yl)phenyl]piperazine-1-carboxylate (700 mg, 2.03 mmol) and DMAP (820 mg, 6.7 mmol) in 1,2-dichloroethane (50 mL) under dry nitrogen was added 2,2,2-trichloroethyl chloroformate (0.62 mL, 4.5 mmol) dropwise and the reaction was refluxed for ½ hour. An additional aliquot of DMAP (820 mg, 6.7 mmol) and 2,2,2-trichloroethyl chloroformate (0.62 mL, 4.5 mmol) were added and the reaction mixture was refluxed for 1 hour. Further aliquots of DMAP (820 mg, 6.7 mmol) and 2,2,2-trichloroethyl chloroformate (0.62 mL, 4.5 mmol) were added and the reaction mixture was refluxed for a total of 4 hours. After cooling to rt, the reaction was poured into aqueous 10% HCl and the product extracted with EtOAc (2×), dried over Na2SO4, concentrated in vacuo and purified by flash chromatography over silica gel (EtOAc/Hex, 3/7, then 1/1) to afford tert-butyl 4-[4-(4-{bis[(2,2,2-trichloroethoxy)carbonyl]amino}-1,2,5-oxadiazol-3-yl)phenyl]piperazine-1-carboxylate.

Provenance & Evidence