Metal and Oxidant-Free Brønsted Acid-Mediated Cascade Reaction to Substituted Benzofurans.

Substituted hydroxy-benzofurans are easily accessible by treatment of resorcinols and 1,2-diaza-1,3-dienes (DDs) under acidic conditions. The reaction happens through an uncommon Michael reaction between aromatic derivatives as aromatic C(sp2)-H nucleophiles and DDs as acceptors. Also, the behavior of different phenols and 2-naphthol was investigated.