Sequential Photochemical and Prins Reactions for the Diastereoselective Synthesis of Tricyclic Scaffolds

Cyclobutene alcohols undergo Prins cyclisations to generate single diastereomers of novel tricyclic heterocycles with five contiguous stereocentres. The reaction times are significantly shorter (ca. 15 min) than with traditional alkene substrates. Stereoselective aza‐Prins cyclisations of cyclobutene amine derivatives give fused aza‐heterocyclic scaffolds. Computational studies provide insight into the observed stereocontrol. The modular approach is flexible, enabling the introduction of a variety of functional groups (including amides, nitriles, alkynes, and arenes) into the sp 3 ‐rich heterocyclic scaffolds.