Chlorosuccinimide → methyl 4-(3-chloro-4-ethyl-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate

Participants

Reaction Steps

A solution of methyl 4-(4-ethyl-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (202 mg, 0.81 mmol) and NCS (108 mg, 0.81 mmol) in N,N-dimethylformamide (4 ml) was stirred in a sealed tube for 1 h at 100° C. Additional NCS (108 mg, 0.81 mmol) was added and the solution stirred 1 h. 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 via column chromatography (2-30% EtOAc in hexanes) affording methyl 4-(3-chloro-4-ethyl-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (135 mg, 0.45 mmol, 56% yield) as a yellow oil: LCMS (ES) m/e 285 (M+H)+.

Provenance & Evidence