反应详情

A suspension of 3-(trifluoromethyl)-1,2,4-triazolo[4,3-a]piperazine hydrochloride (10.94 mmol, 2.5 g) in a mixture of tetrahydrofuran (50 ml) and N,N-diisopropylethylamine (32.8 mmol, 5.42 ml) was added to trichloromethyl chloroformate (13.12 mmol, 1.583 ml) in tetrahydrofuran (50 ml) at 0° C. After one hour at 0° C. the reaction mixture was filtered over decalite and the filter washed with tetrahydrofuran. Then the filtrate was concentrated in vacuo. The residue (4.52 g, crude) was added to 2-aminomethyl-3-chloropyrazine hydrochloride (content 77%; 8.43 mmol, 1.97 g) in a mixture of dichloromethane (50 ml) and triethylamine (25.3 mmol, 3.52 ml) and the reaction mixture was stirred over night at room temperature. Then the reaction mixture was filtered over decalite and the filter washed with dichloromethane. The filtrate was washed with water. The aqueous layer was extracted three times with dichloromethane. The combined organic extracts were washed with brine, dried (sodium sulfate) and concentrated in vacuo. The crude product was purification by column chromatography (silica gel; dichloromethane with gradient 0 to 10% methanol) to give N-((3-chloropyrazin-2-yl)methyl)-3-(trifluoromethyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazine-7(8H)-carboxamide (2.707 g).

1. filtrationAfter one hour at 0° C. the reaction mixture was filtered over decalite
2. washthe filter washed with tetrahydrofuran
3. concentrationThen the filtrate was concentrated in vacuo
4. filtrationThen the reaction mixture was filtered over decalite
5. washthe filter washed with dichloromethane
6. washThe filtrate was washed with water
7. extractionThe aqueous layer was extracted three times with dichloromethane
8. washThe combined organic extracts were washed with brine
9. dry with materialdried (sodium sulfate)
10. concentrationconcentrated in vacuo
11. custompurification by column chromatography (silica gel; dichloromethane with gradient 0 to 10% methanol)