Cesium carbonate → 2-(4-Methoxy-2-methyl-phenyl)-benzo[b]thiophene-5-carboxylic acid ethyl ester

Participants

Reaction Steps

Cesium carbonate (9.70 mmol; 3.19 g) is dried in a resealable tube at 150° C. in vacuo for 2 h and cooled to room temperature. Copper(I) iodide (9.70 mmol; 1.86 g), Pd(OAc)2 (0.24 mmol; 55 mg), triphenylphosphine (0.485 mmol; 128.50 mg), 2-bromo-5-methoxytoluene (9.70 mmol; 2.14 mL), benzo[b]thiophene-5-carboxylic acid ethyl ester (4.85 mmol; 1 g) and anhydrous DMF (24 mL) are added under nitrogen atmosphere and the mixture is stirred at 140° C. After 24 h, Pd(OAc)2 (0.24 mmol; 55 mg) and triphenylphosphine (0.485 mmol; 128.50 mg) are added and the mixture is stirred for 24 more hours. The mixture is allowed to reach room temperature and water and ethyl acetate are added. The suspension is filtered through Celite® and washed with ethyl acetate. The organic layer is separated and the aqueous layer is extracted with ethyl acetate. The organic layers are combined, washed with water, dried (Na2SO4), filtered and concentrated under reduced pressure. The residue is chromatographed (0-10% EtOAc in hexanes) to obtain the title compound (960 mg, 61%) as a colorless waxy solid. LC-ES/MS m/e 326 (M).

Provenance & Evidence