Water → tert-butyl (2S)-2-methyl-5-oxopiperazine-1-carboxylate

Participants

Reaction Steps

(S)-tert-butyl(1-(2-chloroacetamido)propan-2-yl)carbamate (7.5 g, 29.9 mmol) was dissolved in trifluoroacetic acid (30 mL) and stirred for 10 minutes. The reaction mixture was concentrated, dissolved in THF (321 mL) and potassium carbonate (20.7 g, 149.5 mmol) was added and the reaction mixture was refluxed for 12 hours. To the reaction mixture was added (Boc)2O (7.7 mL, 35.9 mmol) and the reaction mixture was refluxed for an additional 5 hours. The reaction mixture was cooled to rt and water was added. The reaction mixture was extracted with EtOAc. The organic layers were combined, dried with Na2SO4, filtered, concentrated and purified by flash column chromatography (0-100% EtOAc in hexanes) to provide the desired compound (5 g, 78%). 1H NMR (600 MHz, DMSO) δ 8.00 (s, 1H), 4.17 (s, 1H) 3.94 (d, J=17.8 Hz, 1H), 3.58 (d, J=17.9 Hz, 1H), 3.43-3.34 (m, 1H), 3.98 (ddd, J=12.7, 4.9, 2.5 Hz, 1H), 1.43-1.38 (s, 9H), 1.10 (d, J=6.7 Hz, 3H).

Provenance & Evidence