Trifluoroacetic acid → Ethyl 2-(4-bromo-2-fluorophenyl)-2-(4-ethyl-3-oxo-1-oxa-4,9-diazaspiro[5.5]undecan-9-yl)acetate

Participants

Reaction Steps

To a solution of tert-butyl 4-ethyl-3-oxo-1-oxa-4,9-diazaspiro[5.5]undecane-9-carboxylate (1 g, 3.35 mmol) in dichloromethane (10 mL) was added TFA (0.775 mL, 10.05 mmol). The reaction mixture was stirred at room temperature overnight, at which point the deprotection had proceeded to completion. The reaction mixture was concentrated in vacuo, dichloromethane was added, and the solution was concentrated in vacuo again. The residue was dissolved with N,N-dimethylformamide (12 mL). To this solution was added potassium carbonate (0.463 g, 3.35 mmol) and ethyl 2-bromo-2-(4-bromophenyl)acetate (1.079 g, 3.35 mmol). The reaction mixture was stirred at 40° C. for overnight, at which point the reaction had proceeded to completion. The reaction mixture was poured into water (120 mL) and was extracted with ethyl acetate (80 mL×3). The combined organic layers were dried and concentrated in vacuo. Crude ethyl 2-(4-bromo-2-fluorophenyl)-2-(4-ethyl-3-oxo-1-oxa-4,9-diazaspiro[5.5]undecan-9-yl)acetate was obtained (590 mg) and was used directly in the next step. MS(ES)+ m/e 457 [M+H]+.

Provenance & Evidence