Sodium Hydroxide → 3,5-Dibromo-6-(trifluoromethyl)pyrazin-2-amine

Temperature

0 °C

To a solution of 22.5 g sodium acetate in 230 ml water was added 21.5 g 3,3-dibromo-1,1,1-trifluoropropanone at reflux and the mixture was refluxed for 10 min. The resulting solution was cooled to 0° C. in an acetone ice bath and added dropwise to a suspension of 19.5 g aminoacetamidine dihydrobromide in 250 ml methanol at −30° C. (dry ice acetone cooling) so that the temperature did not rise above −30° C. during the addition. To the resulting solution was added dropwise a solution of 12.285 g sodium hydroxide in 100 ml water. The mixture was then allowed to warm to room temperature (warm water bath) and then stirred at room temperature for 3 h. The dark reaction mixture was concentrated under aspirator vacuum to remove methanol and extracted with ethyl acetate (4 times). The phases were separated and the organic phase was washed with brine, treated with charcoal and dried with sodium sulfate and evaporated. To the concentrated yellow solution was added heptane and the mixture was seeded whereby crystallization was initiated. The mixture was stirred at room temperature to complete crystallization. The solid was collected by filtration to yield 8.81 g of the title compound as light yellow crystals. The aqueous layers were kept at room temperature for 72 h and then extracted (2 times) with ethyl acetate. The combined organic layers were treated with charcoal and sodium sulfate and evaporated. The residue was taken up in dichloromethane and heptane was added. The mixture was concentrated again until crystallization occurred. The solid was collected by filtration to yield another 2.06 g of the title compound as light yellow crystals. MS (M−H) at 162.1.

1. temperatureat reflux
2. temperaturethe mixture was refluxed for 10 min
3. additiondid not rise above −30° C. during the addition
4. temperatureto warm to room temperature
5. customThe dark reaction mixture
6. concentrationwas concentrated under aspirator vacuum
7. customto remove methanol
8. extractionextracted with ethyl acetate (4 times)
9. customThe phases were separated
10. washthe organic phase was washed with brine
11. additiontreated with charcoal
12. dry with materialdried with sodium sulfate
13. customevaporated
14. additionTo the concentrated yellow solution was added heptane
15. customwhereby crystallization
16. stirringThe mixture was stirred at room temperature
17. customcrystallization
18. filtrationThe solid was collected by filtration

ORD record

ord-691d06819c7345a68740b9feacf431f5

Source dataset

uspto-grants-2012_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08088920B2