Phosphazene base-catalyzed intramolecular cyclization for efficient synthesis of benzofurans via carbon-carbon bond formation.

An organic superbase, phosphazene P4-(t)Bu, functioned as an active catalyst for intramolecular cyclization of o-alkynylphenyl ethers via carbon-carbon bond formation to provide an efficient synthetic method for 2,3-disubstituted benzofurans derivatives under mild reaction conditions without the need for a metal catalyst.