Iron-Catalyzed Cascade Arene-Aldehyde Addition/Cyclizations for the Highly Efficient Synthesis of Xanthenes and Its Analogous: Observation of a C-C Bond Cleavage in Indole-Based Triarylmethanes

An efficient, general, and one-pot procedure for the synthesis of multisubstituted xanthene derivatives through Fe(III)-catalyzed reactions of 2-aryloxybenzaldehydes with electron-rich arenes has been developed. This method offers several advantages such as high selectivities, mild reaction conditions, and easily accessible starting materials. A mechanistic study revealed that a C-C bond cleavage of a triarylmethane intermediate might be involved in the domino process.