Hydrochloric Acid → 5-Chloro-6-hydroxy-3-methyl-benzofuran-2-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

The above prepared 5-chloro-6-methoxy-3-methyl-benzofuran-2-carboxylic acid ethyl ester (2.32 g, 8.63 mmol) was dissolved in 50 mL of CH2Cl2, cooled to 0° C., and treated with BBr3 (17.3 mL of 1M solution in CH2Cl2, 2 eq.). After 5 h at 0° C., the reaction mixture was carefully poured onto crashed ice, twofold extracted with AcOEt, washed with water, dried over magnesium sulfate, and evaporated to dryness. Since substantial amount of free acid had been formed, the crude product was again esterified by treatment with anhydrous HCl in EtOH for 48 h at 48° C. Standard work-up and ensuing flash chromatography (SiO2, hexane/AcOEt=8/2) yielded finally 1.607 g of the title compound as light yellow crystals.

Provenance & Evidence