Facile Synthesis of 2-Fluorobenzofurans: 5-endo-trigCyclization of β,β-Difluoro-o-hydroxystyrenes

Efficient synthetic methods were established for obtaining 2-fluorobenzofurans involving various substituents. Upon being treated with 1,8-diazabicyclo[5.4.0]undec-7-ene under microwave irradiation, the alpha-unsubstituted beta,beta-difluoro-o-hydroxystyrenes underwent nucleophilic 5-endo-trigcyclization to afford the corresponding 2-fluorobenzofurans in high yields. Furthermore, 2-fluoro-3-iodobenzofuran was successfully synthesized, and its transformation to various 3-substituted 2-fluorobenzofurans was demonstrated.