Hydrochloric Acid → Benzyl 3-amino-6-chloro-2-fluorobenzoate

Participants

Reaction Conditions

Reaction Steps

To 4-chloro-2-fluoro-phenylamine (11, 6.30 mL, 57.0 mmol) in 300 mL of tetrahydrofuran, cooled with dry ice/acetone bath under an atmosphere of nitrogen, n-butyllithium (24.4 mL, 2.50 M in hexane) was added slowly. After 20 minutes, 1,2-bis-(chloro-dimethyl-silanyl)-ethane (12.9 g, 60.0 mmol) dissolved in 40.0 mL of tetrahydrofuran was added slowly to the reaction. After 1 hour, n-butyllithium (25.0 mL, 2.50 M in hexane) was added slowly to the reaction. The reaction was stirred at −78° C. for 20 minutes and then allowed to warm to room temperature over 60 minutes. The reaction was cooled to −78° C., followed by slowly adding n-butyllithium (26.0 mL, 2.50 M in hexane). After 80 minutes, benzyl chloroformate (20, 10.0 mL, 70.0 mmol) was added to the reaction. The reaction mixture was stirred at −78° C. overnight followed by addition of 80 mL of water and 25 mL of concentrated hydrochloric acid. The reaction was allowed to warm to room temperature for 2 hours. The organic layer was separated and the aqueous layer was basified with potassium carbonate and extracted with ethyl acetate. The organic layers were combined and washed with brine, dried over anhydrous sodium sulfate, filtered and the filtrate concentrated under vacuum. The resulting material was purified by silica gel column chromatography eluting with 20% ethyl acetate in hexane. Appropriate fractions were combined and concentrated under vacuum to provide the desired compound as a colorless oil (12, 12.5 g, 78.3%). MS(ESI) [M+H+]+=280.0.

Provenance & Evidence