Vortex‐Driven Photocatalytic Cascade Cyclizations for Se‐ and S‐Containing Heterocycle Synthesis

ABSTRACT The regioselective generation of α‐heteroatom‐alkyl radicals has emerged as a powerful strategy for the efficient and selective synthesis of heterocyclic compounds. Herein, we present a visible‐light–driven strategy that enables the regioselective formation of α‐thio alkyl, α‐seleno alkyl, and α‐vinyl thio alkyl radicals. Through a cascade radical cyclization, we achieved efficient and selective synthesis of Se‐ and S‐containing heterocycles, including benzothiochromane, benzoselenochromane, and tetrahydrothiophene derivatives. Particularly, the mechanism study reveals new reactivity patterns for α‐seleno alkyl and α‐vinyl thioether radicals, expanding the frontiers of S/Se‐heterocycles synthesis. We also explored the thin‐film effect using vortex fluidic device (VFD) technology and calculated green metrics for both conventional and VFD driven cascades. The VFD technology facilitates enhanced mass transfer and irradiation efficiency, improving reaction kinetics and enabling high‐yielding selective transformations. This metal‐free platform provides significant advantages over traditional batch setups, including faster reactions, increased productivity, and better reaction conditions control.