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

Participants

Reaction Steps

A solution of methyl 4-(1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (2.5 g, 11.25 mmol) and n-bromosuccinimide (2.002 g, 11.25 mmol) in tetrahydrofuran (56.2 ml) was stirred in a sealed tube for 1 h at 70° C. The reaction mixture was partitioned between H2O-DCM and the aqueous phase was washed several times with DCM. The combined organic fractions were dried over Na2SO4, concentrated and purified by column chromatography (10-50% EtOAc in hexanes yielding methyl 4-(4-bromo-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (2.7 g, 8.97 mmol, 80% yield) as a yellow solid: LCMS (ES) m/e 301, 303 (M, M+2)+.

Provenance & Evidence