Benzo[b]furans are widely distributed in nature,1 and many derivatives, in particular, 2-aryl-substituted ones, exhibit biological activities.2–7 Consequently, various synthetic approaches towards benzo[b]furans have been developed,8 including, for example, electrophilic cyclizations of the corresponding alkynyl- or o-alkenylphenols.9 Many of those processes are palladium-10 or copper-catalyzed.11 Furthermore, metal-free reactions, such as cycloadditions starting ...
