Acetic Acid → (S)-4-(4-Hydroxy-butyl)-2-methyl-3-oxo-piperazine-1-carboxylic acid benzyl ester

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Reaction Steps

A solution of (S)-2-[benzyloxycarbonyl-(2-oxo-ethyl)-amino]-propionic acid methyl ester (24.3 g, 80 mmol) in dichloromethane (130 mL) was added at room temperature over 15 min to a suspension of 4-amino-1-butanol (7.12 g, 80 mmol), acetic acid (9.6 g, 0.16 mol), and sodium triacetoxyborohydride (25.4 g, 0.12 mol), then after 16 h triethylamine (16.2 g, 0.16 mol) was added, and the reaction mixture was concentrated under vacuum. The residue was partitioned between 2 M aq. sodium carbonate solution and ethyl acetate. The organic layer was dried (MgSO4), filtered, and evaporated. Chromatography (SiO2; dichloromethane, then dichloromethane/methanol/25% aq. ammonia solution 90:10:0.25) afforded the title compound (16.8 g, 66%). Yellow oil, MS (ISP)=321.2 (M+H)+.

Provenance & Evidence