反应详情

To a solution of 3′-chloro-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl (3 g, 15.1 mmol, 1 eq) and 1,3-dimethyl-1H-pyrazole-4-carbaldehyde (2.0 g, 16.6 mmol, 1.1 eq) in 1,2-dichloroethane (75 mL) add sodium triacetoxyborohydride (4.8 g, 22.6 mmol, 1.5 eq) and stir at room temperature over the weekend. Add 2 N sodium hydroxide (100 mL), separate the layers, extract the aq. layer twice with DCM (75 mL), dry (magnesium sulfate), filter, concentrate and purify (silica gel chromatography, eluting with 0:100 to 10:90 methanol:DCM). Combine only the fractions which contain the main component and concentrate to give 3′-chloro-4-(1,3-dimethyl-1H-pyrazol-4-ylmethyl)-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl as a viscous yellow oil (2.14 g, 46%). Combine all other fractions which contain main component plus impurities, concentrate then repeat the chromatography step to recover further material (1.6 g, 35%, total yield 81%). MS (ES): m/z=307.1 [M+H]+.

1. customseparate the layers
2. extractionextract the aq. layer twice with DCM (75 mL)
3. dry with materialdry (magnesium sulfate)
4. filtrationfilter
5. concentrationconcentrate
6. custompurify
7. wash(silica gel chromatography, eluting with 0:100 to 10:90 methanol:DCM)
8. concentrationconcentrate