Isobutylamine → di-tert-butyl (2R)-2-((2-methylpropyl)carbamoyl)-1,4-piperazinedicarboxylate

Participants

Reaction Steps

A 20 mL vial was charged with ((2R)-1,4-bis(tert-butoxycarbonyl)-2-piperazinecarboxylic acid (1.52 g, 4.60 mmol, ASW MedChem Inc., New Brunswick, N.J.), HATU (2.10 g, 5.52 mmol, ChemImpex International Inc., Wood Dale, Ill.), 2-methylpropan-1-amine (0.457 mL, 4.60 mmol, Sigma-Aldrich, St. Louis, Mo.), DIPEA (1.60 mL, 9.19 mmol) and DMF (8 mL). The mixture was stirred at room temperature for 2.5 h. and then partitioned between water (80 mL) and EtOAc (50 mL). The aqueous phase was extracted with EtOAc (50 mL). The combined organic extracts were washed with saturated aqueous NaHCO3 (100 mL), water (100 mL) then brine (100 mL). The organics were dried over sodium sulfate, filtered and concentrated in vacuo to afford di-tert-butyl (2R)-2-((2-methylpropyl)carbamoyl)-1,4-piperazinedicarboxylate (2.10 g) as a light brown foam.

Provenance & Evidence