Light-Driven Stereoselective Aryl Bisenone Cycloaddition: A Metal-Free Strategy for the Construction of Functionalized Pyrrolidines and Tetrahydrofurans

In this study, we report an exploratory study on the reductive cyclization of nitrogen- and oxygen-containing aryl bisenones, enabling the efficient synthesis of highly functionalized pyrrolidines and tetrahydrofurans under visible light irradiation. The transformation proceeds through a photocatalytic cyclization promoted by catalytic amounts of Eosin Y, with Schreiner's thiourea and Hantzsch ester acting as mediators under visible green light irradiation. The transformation is stereoselective and affords the five-membered heterocycle as a single, trans isomer. Moreover, the introduction of chiral oxazolidinone auxiliaries onto aryl bisenone precursors allowed the formation of chiral, highly substituted trans pyrrolidines and tetrahydrofurans in good yields, although with modest stereoselectivities.