Hydrochloric Acid → 3-(Chloromethyl)-5-fluorobenzo[b]-thiophene

Participants

Reaction Conditions

Reaction Steps

A mixture of formaldehyde 37% (31 g) and ZnCl2 (10 g) in ethyl acetate (90 ml) and HCl 12N (190 ml) was stirred at −10° C. HCl (gas) was allowed to bubble through the mixture until saturation (at −10° C.). 5-fluorobenzo[b]thiophene (0.35 mol) was added dropwise at <0° C. The reaction mixture was stirred overnight at room temperature. Toluene (200 ml) was added and the mixture was stirred vigorously. The organic layer was separated, washed with an aqueous NaHCO3 solution and with water, dried, filtered and the solvent was evaporated. The residue was triturated under hexane, filtered off and dried, yielding 58 g of 3-(chloromethyl)-5-fluorobenzo[b ]thiophene (82.6%) (interm. 10).

Provenance & Evidence