Chiral Lewis Acid-Catalyzed Intramolecular [2 + 2] Photocycloaddition: Enantioselective Synthesis of Azaarene-Functionalized Azabicyclo[2.1.1]hexanes and Bicyclo[1.1.1]pentanes

We present an asymmetric intramolecular [2 + 2] photocycloaddition reaction enabled by a dual catalyst system involving DPZ as a photosensitizer and chiral Sc(III) complex, leading to azaarene-functionalized 2-azabicyclo[2.2.1]hexanes (aza-BCHs). The approach efficiently preventing racemization during subsequent nitrogen-deletion skeletal editing of aza-BCHs to yield 2-substituted bicyclo[1.1.1]pentanes (BCPs). The method achieves high ee and broad substrate scope, including the successful formation of all-carbon quaternary stereocenters. Furthermore, the successful activation of simple azaarene substrates by chiral Lewis acids in asymmetric photocatalysis highlights a notable contribution to this field.