methyl 4-bromo-5-ethylthiophene-2-carboxylate synthesis

Yield:1047645-89-5 100%

Reaction Conditions:

with sulfuric acid at 50; for 48 h;

Steps:

98.a

To a solution of 4-bromo-5-ethyl-2-thiophenecarboxylic acid (1 g, 4.25 mmol) in methanol (21.27 ml) was added sulfuric acid (0.23 ml_, 4.25 mmol). The resulting solution was stirred at 50 ⁰C for 48h. H₂O (50 ml.) was added and the reaction was cooled to 0 ⁰C in an ice-bath. The pH was adjusted to -12 and the aqueous phase was washed several times with DCM. The combined organic fractions were dried over Na₂SO₄, concentrated and used directly without further purification providing methyl 4-bromo-5-ethyl-2-thiophenecarboxylate (1.060 g, 4.25 mmol, 100 % yield): LCMS (ES) m/e 248, 250 (M, M+2)+.

References:

WO2008/98104,2008,A1 Location in patent:Page/Page column 195