3-AMINO-6-BROMO-1H-PYRAZINE-2-THIONE synthesis

Yield:6863-75-8 0.15 g

Reaction Conditions:

with hydrogen sulfide;potassium hydroxide in methanol; for 4 h;Reflux;

Steps:

IIb-33 Intermediate IIb-33. 3-Amino-6-bromopyrazine-2-thiol

3-Amino-6-bromopyrazine-2 -thiol llb-33KOH (1 .08 g, 19.7 mmol) was added to the solution 2-amino-3,5-dibromo- pyrazine (0.5 g, 1 .97 mmol) in Methanol (6 ml). H₂S gas (prepared from 5.0 g of FeS and 10 ml of HCI) was purged to the mixture for 1 hour and the result- ing mixture was refluxed for 3 hours. After completion of the reaction the mixture was cooled and evaporated to dryness under reduced pressure. Water (20 ml) was added and the mixture neutralized with diluted HCI solution and extracted with ethyl acetate. The organic phase was washed with brine, dried over sodium sulphate and concentrated under reduced pressure. Yield was 0.15 g.

References:

WO2014/191632,2014,A1 Location in patent:Page/Page column 54; 55