反应详情

A solution of octahydro-2H-pyrido[1,2-a]pyrazine (4 gm, 0.029 moles), 2,6-dichloropyrazine (4.28 gm, 0.029 moles) and triethylamine (8 ml. 0.06 moles) in 75 ml of acetonitrile is heated under reflux for 4 hours. After cooling, the precipitate is filtered off and washed with a little acetonitrile. The filtrate is concentrated under reduced pressure and the resulting residue is partitioned between water and ether. The aqueous layer is made basic with potassium carbonate and extracted 3 times with 100 ml. portions of ether. The combined ether layer is washed with saline and dried over sodium sulfate. After filtering off the drying agent the clear filtrate is made acidic with dry hydrogen chloride gas. The precipitate is filtered off, washed with ether and dried. After two crystallizations from ethanol there is obtained a 4.5 gm (54 percent) yield of title compound, m.p. 298°-301° C.

1. temperatureunder reflux for 4 hours
2. temperatureAfter cooling
3. filtrationthe precipitate is filtered off
4. washwashed with a little acetonitrile
5. concentrationThe filtrate is concentrated under reduced pressure
6. customthe resulting residue is partitioned between water and ether
7. extractionextracted 3 times with 100 ml
8. washThe combined ether layer is washed with saline
9. dry with materialdried over sodium sulfate
10. filtrationAfter filtering off the drying agent the clear filtrate
11. filtrationThe precipitate is filtered off
12. washwashed with ether
13. customdried
14. customAfter two crystallizations from ethanol