Acetic Acid → HCID 66999388, compound

Participants

Reaction Steps

Saturated aq. sodium hydrogencarbonate solution (1.25 ml) was added to a solution of (S)-4-(3-hydroxy-propyl)-2-methyl-3-oxo-piperazine-1-carboxylic acid tert-butyl ester (1.00 g, 3.67 mmol), potassium bromide (44 mg, 0.37 mmol), and 2,2,6,6-tetramethylpiperidin-1-oxyl (6 mg, 0.04 mmol) in dichloromethane (50 ml). Sodium hypochlorite solution (10% in water, 2.2 ml, 3.7 mmol) was added portionwise at 0° C., and the course of the oxidation was monitored by thin layer chromatography. After all starting material had reacted, the reaction mixture was washed with sat. aq. sodium hydrogencarbonate solution, and the aqueous layer was extracted twice with dichloromethane. The organic phases were pooled, dried (MgSO4), filtered, and evaporated, thus affoding (S)-4-(3-oxo-propyl)-2-methyl-3-oxo-piperazine-1-carboxylic acid tert-butyl ester (950 mg). This was dissolved in dichloromethane (20 ml) and added over 20 min to a suspension of piperidine (297 mg, 3.49 mmol) triethylamine (353 mg, 3.49 mmol), acetic acid (419 mg, 6.98 mmol) and sodium triacetoxyborohydride (90% purity; 908 mg, 3.85 mmol) in dichloromethane (20 ml). After 16 h the reaction mixture was washed with 2 M aq. sodium carbonate solution, the organic layer was dried (MgSO4), filtered, and evaporated. Chromatography (SiO2; dichloromethane/methanol/25% aq. ammonia solution 90:10:0.25) produced the title compound (1.07 g, 86%). Light yellow oil, MS (ISP)=340.2 (M+H)+.

Provenance & Evidence