Pyridine → (S)-4-[(S)-1-Acetoxymethyl-3-((S)-4-hydroxy-6-aza-spiro[2.5]oct-6-yl)-propyl]-2-methyl-3-oxo-piperazine-1-carboxylic acid benzyl ester

Participants

Reaction Steps

Acetic anhydride (42 mg, 0.41 mmol) was added at 0° C. to a solution of (S)-4-[(S)-3-((S)-4-hydroxy-6-aza-spiro[2.5]oct-6-yl)-1-hydroxymethyl-propyl]-2-methyl-3-oxo-piperazine-1-carboxylic acid benzyl ester (intermediate 39; 182 mg, 0.41 mmol) and pyridine (32 mg, 0.41 mmol). The ice bath was removed, then after 16 h excess reagent was destroyed by addition of diethylamine (15 mg, 0.21 mmol). After evaporation of volatile material, chromatography (SiO2; dichloromethane to dichloromethane/methanol/25% aq. ammonia solution 90:10:0.25) produced the title compound (143 mg, 72%). Colorless gum, MS (ISP)=488.4 (M+H)+.

Provenance & Evidence