Bromine → Methyl 4-bromo-5-chlorothiophene-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of methyl 5-chloro-2-thiophenecarboxylate (7 g, 39.6 mmol) and aluminum trichloride (7.93 g, 59.4 mmol) in chloroform (79 ml) at 25° C. was added bromine (2.86 ml, 55.5 mmol). The resulting solution stirred at 25° C. for 2 h. Ice chips were added to quench and the solution was partitioned between H2O-DCM. The aqueous phase was washed several times with DCM and the combined organic fractions were dried over Na2SO4, concentrated and purified via column chromatography (silica, 5% EtOAc in hexanes) affording methyl 4-bromo-5-chloro-2-thiophenecarboxylate (7.2 g, 28.2 mmol, 71.1% yield) as a white solid; LCMS (ES) m/z=255, 257 (M, M+2)+.

Provenance & Evidence