Synthesis of Isoxazolidines from Substituted Vinylnitrones and Conjugated Carbonyls via Visible‐Light Photocatalysis

Herein we report the first redox‐neutral visible‐light photocatalytic intermolecular dipolar cycloaddition for the diastereoselective synthesis of isoxazolidines. We have found that vinyl nitrones with a diverse substitution pattern undergo visible‐light‐promoted cycloadditions with conjugated carbonyls in the presence of catalytic amounts of Ru(bpy)3Cl2, with the reaction proceeding with high yields and good selectivities. A redox‐neutral pathway is proposed as the primary photoredox mechanism for this transformation. Redox neutral pathway: This effort highlights the first highly stereoselective photocatalytic dipolar cycloaddition of vinyl nitrones and conjugated carbonyl derivatives. This method allows for the synthesis of complex heterocycles under very mild conditions with good yields and selectivities. The data observed justifies a potential redox‐neutral photocatalytic pathway for the observed products.