Tandem Access to Acridones and their Fused Derivatives: [1+2+3] Annulation of Isocyanides with Unsaturated Carbonyls

A wide range of acridones and their cyclo[b]‐fused derivatives are efficiently constructed by a double annulation of o‐enoyl arylisocyanides with α, β‐unsaturated carbonyls under simple metal‐free condition. This protocol is general, efficient and practical, featuring the successive formation of two rings by a one‐pot domino transformation. A tandem process involing an isocyanide‐based [1+4] cycloaddition, an aminofuran‐based intramolecular [4+2] cycloaddition, ring opening and aromatization is proposed for the transformation.