Reaction #85836

Reaction equation

NaOH

HBr

tert-butyl 4-(4-amino-2-fluorophenyl)piperazine-1-carboxylate

NaNO2

HBr

→

1-(4-bromo-2-fluorophenyl)piperazine

Solvents

H2O

Conditions

Workup

1. 1
   TemperatureThe reaction was heated to 60° C.
2. 2
   workup.STIRRINGstirred for 2 hours
3. 3
   TemperatureAfter cooling
4. 4
   Extractionextracted with EA
5. 5
   Washwashed with H2O and brine
6. 6
   Otherdried
7. 7
   Concentrationconcentrated
8. 8
   Otherto give black solid

Procedure

To a solution of tert-butyl 4-(4-amino-2-fluorophenyl)piperazine-1-carboxylate (885 mg, 3 mmol) in 8 mL of aq HBr was added a solution of NaNO2 (228 mg, 3.3 mmol) in 2 mL of H2O at 0° C., then the mixture was stirred at 0° C. for 40 minutes. After that, the mixture was poured into a solution of CuBr (905 mg, 6.3 mmol) in 8 mL aq HBr at 0° C. The reaction was heated to 60° C. and stirred for 2 hours. After cooling, the mixture was based with 2M NaOH to pH=8-9 and extracted with EA, washed with H2O and brine, dried and concentrated to give black solid. MS (m/z): 261 (M+H)+

Source