Novel and Convenient Synthesis of Benzofurans from Dihydrocoumarins

7-Hydroxy-3,4-dihydrocoumarin-4-carboxylic acid (7), conveniently prepared from m-resorcinol and maleic anhydride, was surprisingly transformed by acid anhydride and pyridine into the corresponding ketone, 4-alkanoyl analog 11. The latter reacted in turn with acidic alcohol yielding benzofuran-3-yl-acetic ester 16.