1-Methyl-1H-pyrazole-4-carbaldehyde → 3'-Chloro-4-(1-methyl-1H-pyrazol-4-ylmethyl)-3,4,5,6-tetrahydro-2H-[1,2']bipyrazine

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Reaction Steps

Dissolve 3′-chloro-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl (3.43 g, 17.3 mmol) in tetrahydrofuran (100 mL). Add 1-methyl-1H-pyrazole-4-carbaldehyde (2.244 g, 20.38 mmol) in dry tetrahydrofuran (5 mL), stir for 10 min. at room temperature, add sodium triacetoxyborohydride (4.32 g, 20.4 mmol), subject the reaction to ultrasound and stir for 6 hr. at room temperature. Add saturated aq. sodium hydrogen carbonate (100 mL) then 2 N sodium hydroxide (10 mL) to the mixture and extract with DCM (2×200 mL). Pass the combined DCM extracts through an IST Phase Separator Frit®, concentrate and purify (silica gel chromatography, eluting with 0:100 to 8:92 methanol:DCM), to give 3′-chloro-4-(1-methyl-1H-pyrazol-4-ylmethyl)-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl as a crystalline solid (5.21 g, 92%). MS (ES): m/z=293.1 [M+H]+.

Provenance & Evidence