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

Participants

Reaction Steps

A solution of methyl 5-ethyl-4-(1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (980 mg, 3.92 mmol) [prepared in Example 98] and N-bromosuccinimide (697 mg, 3.92 mmol) in tetrahydrofuran (19.6 ml) was stirred in a sealed tube for 1 h at 70° C. The reaction mixture 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, 10-40% EtOAC in hexanes) yielding methyl 4-(4-bromo-1-methyl-1H-pyrazol-5-yl)-5-ethyl-2-thiophenecarboxylate (1.1 g, 3.34 mmol, 85% yield) as a yellow oil: LCMS (ES) m/e 329, 331 (M, M+2)+.

Provenance & Evidence