3-(2,5-Difluoro-phenyl)-acrylic acid → 3-(2,5-Difluorophenyl)propanoic acid

Participants

Reaction Steps

2,5-Difluorocinnamic acid (5.0 g, 27.2 mmol) was dissolved in 25 ml of ethanol and a catalytic amount of 10% Pd on carbon was added. The reaction mixture was hydrogenated at normal pressure for a period of 3 hrs. Filtration through celite and evaporation of the solvent afforded crude 3-(2,5-difluorophenyl)-propionic acid. This acid was dissolved in 75 ml of toluene and 5 ml of thionyl chloride was added. The reaction mixture was heated at +110° C. for a period of 2 hrs. Evaporation of the solvent afforded crude 3-(2,5-difluorophenyl)-propionyl chloride, which was dissolved in 25 ml of carbon disulfide and added drop wise to a suspension of 4 g of aluminium chloride in 100 ml of carbon disulfide. The reaction mixture was refluxed for 2 hrs and gave after work up and re-crystallization from ethanol 975 mg (22%) of 4,7-difluoro-1-indanone.

Provenance & Evidence