Sulfuric Acid → Tert-butyl 5-bromothiophene-2-carboxylate

Participants

Reaction Steps

To a solution of anhydrous MgSO4 (11.60 g, 96.4 mmol) in 100 mL CH2Cl2 was added concentrated H2SO4 (1.45 mL, 24.1 mmol) and the mixture was stirred for 15 minutes followed by addition of 5-bromo-thiophene-2-carboxylic acid (5.0 g, 24.1 mmol). After stirring for 1 minute, tert-butanol (11.6 g, 20 mmol) was added and the reaction was stirred at room temperature for 16 h. The reaction was quenched with saturated NaHCO3. The layers were separated, the aqueous layer was extracted with CH2Cl2, and the combined organic layers were dried over MgSO4. The organic solution was concentrated to give a clear oil which was purified via medium pressure chromatography (3% EtOAc in hexanes) to afford the title compound of Step A (4.97 g). 1H NMR (400 MHz, CDCl3) δ 7.45 (d, 1H), 7.02 (d, 1H), 1.54 (s, 9H).

Provenance & Evidence