Methanesulfonic Acid → 2-Dimethylamino-5-fluoro-6-methoxybenzo[b]thiophene

Participants

Reaction Steps

A solution of 16.6 g (68.2 mmol) of N,N-dimethyl-3-fluoro-4-methoxy-2-hydroxyphenylthioacetamide (Part A) in 400 mL of CH2Cl2 was treated with 22.0 mL (339.0 mmol) of MeSO3H in a dropwise manner. The reaction was stirred at room temperature for 4 h, was cooled to 0° C., and was quenched by the careful addition of 500 mL of saturated aqueous NaHCO3. The two layers were separated and the aqueous layer was extracted with EtOAc (5×200 mL). The combined organic layers were washed with 500 mL of saturated aqueous NaHCO3 and 500 mL of H2O, dried over Na2SO4, and filitered. Evaporation of the solvent in vacuo afforded 21.4 g of an oil which was purified by flash chormatography (SiO2; gradient of 10% then 20% EtOAc in hexanes) to give 2.87 g (12.7 mmol; 19%) of the title compound as a light pink solid

Provenance & Evidence