Oxetanes and azetidines continue to attract interest as valuable motifs in medicinal chemistry. 1 These motifs have increasingly appeared in clinical candidates, including Lanraplenib, 2 Crenolanib, 3 and FDA-approved Siponimod 4 and Baricitinib (Figure ). The low molecular weight and high polarity of 4-membered heterocycles can provide attractive molecular properties, as well as replacement groups for sensitive and metabolically exposed functionalities. 3,3-Disubstituted oxetanes, in particular, present interesting opportunities as bioisosteres, providing comparable features to carbonyl groups and advantages due to increased steric protection, which improves stability to nucleophiles and acidic conditions. The attractive features of 4-membered rings have prompted the development of several new approaches for their synthesis and late-stage incorporation to overcome the challenges posed by their ring strain and potential instability. Recent years have seen developments in the generation and reaction of oxetane and azetidine radicals as reactive intermediates. Radicals have been generated from oxetane itself and azetidine derivatives at the activated C2-position, where the radical is stabilized by the adjacent lone pair. 8 Radical generation at the 3-position must compete with possible HAT processes at the 2position, which would generate a heteroatom-stabilized radical, and hence requires a group that can act as a radical precursor. Recently, oxetane functionalization has been achieved using visible light mediated photoredox catalysis, which has emerged as a powerful and general tool to generate radical species under mild conditions. 3-Iodo-oxetane and azetidine are increasingly employed in coupling reactions, while there are only limited examples from oxetane-3-carboxylic acid. To date there have been very few and isolated examples of tertiary oxetane radicals at the 3-position (Scheme 1).