Photoredox‐Catalyzed Decarboxylation of Oxetane‐2‐Carboxylic Acids and Unique Mechanistic Insights

Abstract Oxetanes are valuable motifs in medicinal chemistry applications, with demonstrated potential to serve as bioisosteres for an array of functional groups. Through the visible‐light‐mediated photoredox hydrodecarboxylation of 2‐aryl oxetane 2‐carboxylic acids this work enables access to the products of a [2+2]‐photocycloaddition between alkenes and aryl aldehydes without the challenges associated with a traditional UV‐light‐mediated Paternò‐Büchi reaction. Investigation into the hydrodecarboxylation mechanism reveals substrate‐dependent modes of initiation under the conditions reported herein. Divergence in diastereomeric outcome is observed, with mechanistic probes elucidating key hydrogen‐bonding and steric interactions.