N-bromobutanimide → methyl 4-(4-bromo-1-methyl-1H-pyrazol-5-yl)-5-methyl-2-thiophenecarboxylate

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Reaction Steps

A solution of methyl 5-methyl-4-(1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (580 mg, 2.45 mmol) and n-bromosuccinimide (437 mg, 2.45 mmol) in tetrahydrofuran (12.300 ml) was stirred in a sealed tube for 1 h at 70° C. The solution was then partitioned between H2O-DCM and the aqueous phase was washed several times with DCM. The combined organic fractions were dried over Na2SO4, concentrated then purified via column chromatography (silica, 20% EtOAc in hexanes) yielding methyl 4-(4-bromo-1-methyl-1H-pyrazol-5-yl)-5-methyl-2-thiophenecarboxylate (600 mg, 1.90 mmol, 78% yield) as a yellow oil: LCMS (ES) m/e 314, 316 (M, M+H)+.

Provenance & Evidence