Regioselective Synthesis of Benzofuranones and Benzofurans.

Reaction of 3-hydroxy-2-pyrones with nitroalkenes bearing ester groups gives benzofuranones. The reaction allows regioselective preparation of the benzofuranones with programmable substitution at any position. Complex substitution patterns are readily created. The substituted benzofuranones can be converted to substituted benzofurans.