Diisopropylethylamine → HCID 86701005, compound

Participants

Reaction Steps

DIPEA (105 g, 0.81 mol) was added to a solution of tert-butyl piperazine-1-carboxylate (25.0 g, 0.134 mol) in DCM (250 mL) at 0° C., followed by the addition of triphosgene (92 g, 0.27 mol) in portions over a 40 min time period. The reaction mixture was stirred for at rt for 3 hrs, filtered and concentrated to afford 1-tert-butyl 4-trichloromethyl piperazine-1,4-dicarboxylate (50 g) as an oil. A solution of 1-tert-butyl 4-trichloromethyl piperazine-1,4-dicarboxylate (50 g, 0.145 mol) in THF (50 mL) was added dropwise over a 30 minute period to a solution of hydrazine hydrate (18 mL, 0.434 mol) in THF (150 mL). The reaction mixture was stirred at rt for 2 hrs, diluted with saturated sodium chloride (50 mL) and exacted with EtOAc (3×). The combined organic layer was washed with saturated sodium chloride (2×), dried with Na2SO4, and concentrated. The residue was purified by crystallization (3:1 petroleum ether/EtOAc) to obtain of tert-butyl 4-(hydrazinecarbonyl)piperazine-1-carboxylate, (13 g, 40% for two steps). ESI-MS (EI+, m/z): 245 [M+H]+. 1H-NMR (500 MHz, CDCl3): δ5.92 (s, 1H), 3.45-3.35 (m, 8H), 1.41 (s, 9H).

Provenance & Evidence