Reaction #40275

Reaction equation

trimethylacetyl chloride

2-amino-5-bromopyrazine

dichloromethane

pyridine

→

title compound

Yield 90.4%

N-(5-bromo-pyrazin-2-yl)-2,2-dimethylpropionamide

Yield 90.4%

Solvents

ethanol

Conditions

Workup

1. 1
   OtherA 3-necked 1 L round bottomed flask equipped with a magnetic stirrer
2. 2
   Temperaturethat raised the temperature of the mixture from 22° C. to 44° C
3. 3
   Otherreaction
4. 4
   Concentrationconcentrated by distillation at atmospheric pressure
5. 5
   workup.DISTILLATIONAfter 240 mL of distillate had collected
6. 6
   Otherreached 68° C.
7. 7
   workup.ADDITION100 mL of water was added slowly
8. 8
   Temperaturewhile maintaining the temperature of the mixture at ca. 68° C
9. 9
   workup.ADDITIONAfter the addition
10. 10
    Temperatureto cool to room temperature
11. 11
    workup.STIRRINGstirred overnight
12. 12
    FiltrationThe solid was collected by filtration
13. 13
    Washwashed with 100 mL of ethanol:water 1:1
14. 14
    Otherdried by suction

Procedure

A 3-necked 1 L round bottomed flask equipped with a magnetic stirrer, thermometer, condenser and nitrogen inlet/outlet was charged with 50.00 g (287.4 mmol) of 2-amino-5-bromopyrazine (1), 218 mL of dichloromethane and 30.50 mL (377.1 mmol) of pyridine. Then, 39.30 mL (319.1 mmol) of trimethylacetyl chloride (PivCl) was added dropwise over 5 min. An exotherm ensued that raised the temperature of the mixture from 22° C. to 44° C. After stirring at ca. 40° C. for 2 h, HPLC analysis indicated complete reaction. The reaction mixture was diluted with 200 mL of ethanol, then concentrated by distillation at atmospheric pressure. After 240 mL of distillate had collected and the temperature of the mixture reached 68° C., 100 mL of water was added slowly, while maintaining the temperature of the mixture at ca. 68° C. After the addition was complete, the resulting suspension was allowed to cool to room temperature and stirred overnight. The solid was collected by filtration, washed with 100 mL of ethanol:water 1:1 and dried by suction to give 67.08 g (90.4% yield) of the title compound as a light beige solid; 98.21% pure as determined by HPLC analysis (HPLC column Zorbax Eclipse XDB-C8, 4.6×50 mm, 1.8 μm, eluent 5-100% acetonitrile/water+01. % TFA over 5 min at 1 mL/min, detection at UV 250 nm, retention time 4.22 min).

Source