A new efficient synthesis of efaroxan

The key step of the synthesis of efaroxan was the dihydrobenzofuran ring formation involving an intramolecular cyclization of the tertiary alcohol intermediate with the fluoroaromatic moiety in basic medium. This carbinol was prepared according to two routes, either from reaction of a benzyl Grignard reagent with an alpha-ketoester, or from a Darzens condensation.