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 (1 g, 3.99 mmol)[prepared in Example 98] and N-bromosuccinimide (0.711 g, 3.99 mmol) in tetrahydrofuran (8 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)-5-ethyl-2-thiophenecarboxylate (1.2 g, 3.54 mmol, 89% yield) as an orange oil: LCMS (ES) m/e 329, 331 (M, M+2)+.

Provenance & Evidence