A sequential Friedländer and anionic benzannulation strategy for the regiodefined assembly of unsymmetrical acridines

An efficient sequential double-annulation strategy has been developed to afford a series of unsymmetrical acridines with high yield and regioselectivity for the first time. This simple protocol enables the sequential assembly of two aromatic rings from simple starting materials. The reaction proceeds via modified Friedlander annulation and subsequent base-mediated benzannulation with acrylates as Michael acceptors. A range of substrate scope and functional group tolerance is observed. Late-stage synthetic modification is also explored to access novel unsymmetrical acridines in good yield. Regiodefined synthesis of unsymmetrical acridines was achieved through sequential double-annulation strategy for the first time.

Automated summary

An efficient sequential double-annulation strategy has been developed to synthesize a series of unsymmetrical acridines. This simple protocol enables the assembly of two aromatic rings from simple starting materials and shows a good substrate scope and functional group tolerance.