Benzyl chloroformate → Benzyl 2-cyano-4-fluorobutan-2-ylcarbamate

Participants

Reaction Steps

The crude rac-2-amino-4-fluoro-2-methylbutanonitrile hydrochloride product from Example 72A was initially charged in 165 ml of tetrahydrofuran/water (1:1), and 28.57 g (206.71 mmol) of potassium carbonate and 9.46 g (55.46 mmol) of benzyl chloroformate were added. The reaction mixture (biphasic mixture) was stirred at room temperature overnight. Another 1.72 g (10.1 mmol) of benzyl chloroformate were added to the reaction and the mixture was stirred at room temperature for a further 2 h. Subsequently, the biphasic system was separated and the aqueous phase was extracted twice with ethyl acetate. The combined organic phases were washed once with saturated aqueous sodium chloride solution, and then dried over sodium sulphate, filtered and concentrated by rotary evaporation. The residue was purified by means of silica gel chromatography (eluent:cyclohexane/ethyl acetate gradient=20/1 to 5/1). 5.04 g of the target compound were obtained (38% of theory over two stages, 96% purity).

Provenance & Evidence