Hydrochloric Acid → (2R,5R)-tert-Butyl 5-(hydroxymethyl)-2-methylpiperazine-1-carboxylate

Participants

Reaction Steps

To the piperazine dihydrochloride (20 g, 119 mmol) in MeOH (96 mL) at 0° C. (ice bath) was added triethylamine (48.7 mL, 357 mmol). tert-Butyl dicarbonate (61 g, 280 mmol) in MeOH (145 mL) was added over 30 min. The reaction temperature was maintained at <10° C. for 1 h, warmed to ambient temperature over 1 h and then heated to 50° C. for 18 h. The reaction was concentrated and the residue dissolved in ethanol (397 mL). A solution of NaOH (23.8 g, 595 mmol) in water (397 mL) was added and the reaction heated to 100° C. for 18 h, then cooled to ambient temperature. Mixture was neutralised with 1M HCl (−300 mL) to pH 9 (using a pH meter), then extracted with chloroform (3×700 mL), dried over sodium sulfate, filtered and concentrated. The residue was redissolved in MeOH and concentrated, then dried in vacuo at 40° C., to give the title compound (21 g, 75%) as a colourless solid. 1H NMR (Me-d3-OD): 4.20-4.07 (1H, m), 3.79 (1H, dd), 3.71-3.58 (2H, m), 3.54 (1H, dd), 3.24 (1H, dd), 3.18-3.01 (1H, m), 3.01-2.89 (1H, m), 2.55 (1H, dd), 1.48 (9H, s), 1.25 (3H, s).

Provenance & Evidence