Acetyl chloride → 2-(tert-Butoxycarbonyl-cyclopropyl-amino)-3-oxo-butyric acid ethyl ester

Participants

Reaction Steps

To solution of 63 ml (1 M in THF, 63 mmol) of lithium hexamethyldisilylazide cooled to −78° C. under Ar was added, drop wise, a solution of 7.3 g (30 mmol) of (tert-butoxycarbonyl-cyclopropyl-amino)-acetic acid ethyl ester in 10 ml of THF. The mixture was brought to −40° C. and stirred for 1 h. 2.3 ml (30 mmol) of acetyl chloride was then added and the mixture allowed to reach room temperature over 1 h after which time the reaction was quenched by addition to 10% citric acid solution. The mixture was then extracted with EtOAc, dried with sodium sulfate and concentrated. Purification by flash column chromatography [n-heptane/EtOAc 1:9 to 2:8] afforded 5.8 g (67%) of the title compound as colorless oil, partially contaminated with the starting material. MS: 286.1 (MH+).

Provenance & Evidence