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

Abstract

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.

Palladium-Catalyzed Dual C–H Carbonylation of Diarylamines Leading to Diversified Acridones under CO-Free Conditions

“…22 Recently, Xu and co-workers reported a double annulation of o-enoyl arylisocyanides with α,β-unsaturated carbonyls leading to a wide range of acridones (Scheme 1a). 23 Meanwhile, the group of Zhang and Ma developed an interesting decarbonylative rearrangement of N-aryl isatins to afford acridones (Scheme 1b). 24 Despite these achievements, they generally suffer from the substrate engineering, namely the multistep synthesis of starting materials, contradicting the principle of step-economy as well as atom-economy.…”

“…Traditional protocols to access acridones mainly focused on intramolecular cyclization of 2-aminobenzophenones or N -arylsubstituted acids, as well as their derivatives, , and intermolecular cyclization from anthranilic acid derivatives with aryne or aryliodonium and so forth . Recently, Xu and co-workers reported a double annulation of o -enoyl arylisocyanides with α,β-unsaturated carbonyls leading to a wide range of acridones (Scheme a) . Meanwhile, the group of Zhang and Ma developed an interesting decarbonylative rearrangement of N -aryl isatins to afford acridones (Scheme b) .…”

Cascade reaction of o-enoyl arylisocyanide and o-hydroxy aromatic aldimine: diastereoselective access to a polycyclic spirobenzoxazine chromeno[4,3-b]pyrrole derivative

“…12 The same group has also disclosed that the [1+2+3] cyclization of o -enoyl arylisocyanides and α,β-unsaturated carbonyls could construct acridones and their cyclo[ b ]-fused derivatives (Scheme 1b). 13 Although much progress has been achieved, investigation on the new reaction modes of o -enoyl arylisocyanide remains under exploited. In the past few years, we have been interested in exploring new reactivities of isocyanide, and thus a series of synthetic conversions have been developed.…”