N-bromobutanimide → 4-(4-bromo-1-methyl-1H-pyrazol-5-yl)-5-chloro-2-thiophenecarboxylic acid

Participants

Reaction Steps

A solution of 5-chloro-4-(1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylic acid (50 mg, 0.21 mmol)[prepared in Example 95] and NBS (36.7 mg, 0.21 mmol) in tetrahydrofuran (2.06 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 and concentrated yielding 4-(4-bromo-1-methyl-1H-pyrazol-5-yl)-5-chloro-2-thiophenecarboxylic acid (82 mg, 0.16 mmol, 79% yield) as a yellow oil: LCMS (ES) m/e 257, 259 (M, M+2)+.

Provenance & Evidence