Potassium Carbonate → tert-Butyl 4-{3-[4-(hydroxymethyl)phenyl]pyrazin-2-yl}piperazine-1-carboxylate

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Reaction Steps

Dissolve 3′-chloro-2,3,5,6-tetrahydro-[1,2′]bipyrazinyl-4-carboxylic acid tert-butyl ester (1.29 g, 4.35 mmol) in tetrahydrofuran (12 mL) and water (6 mL). Add potassium carbonate (1.32 g, 9.56 mmol) then 4-hydroxymethylbenzeneboronic acid (0.924 g, 6.08 mmol) and degas with nitrogen for 15 min. Add tri-n-butylphosphine tetrafluoroborate (50 mg, 0.174 mmol) and tris(dibenzylideneacetone)dipalladium(0) (80 mg, 0.0869 mmol) and reflux for 20 hr. Cool to room temperature then dilute with saturated aq. sodium bicarbonate and extract 3 times with ethyl acetate. Dry (sodium sulfate), filter, concentrate and purify (silica gel chromatography, eluting with 3:97 methanol (with 2 M ammonia): DCM), to give a yellow oil. Dissolve the oil in methanol and add ammonium chloride then sonicate the mixture for 10 min. Evaporate the solution to give 3′-(4-hydroxymethyl-phenyl)-2,3,5,6-tetrahydro-[1,2′]bipyrazinyl-4-carboxylic acid tert-butyl ester as a yellow semisolid (0.565 g, 35%). MS (ES): m/z=371 [M+H]+.

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