Recent advances in photochemical rearrangements involving diradicals

Abstract

Photochemical rearrangements through diradical intermediates represent a transformative paradigm in modern organic synthesis, offering unparalleled control over molecular architecture through radical-based skeletal remodeling. This comprehensive review presents a unified mechanistic framework for understanding and exploiting these powerful transformations, systematically categorizing them into three key classes: (1) ring-expanding processes that facilitate strategic molecular growth, (2) ring-contracting reactions for complexity generation, and (3) programmable ring constructions spanning small to medium-sized systems. Recent breakthroughs in visible-light mediated photochemistry have dramatically expanded the scope of these transformations, achieving remarkable levels of efficiency and selectivity. We showcase these advances through transformative applications in natural product synthesis and functional materials design, featuring case studies of complex molecular targets assembled via innovative diradical strategies. Looking forward, we identify three key growth areas: (1) synergistic integration of energy transfer catalysis with diradical reactivity, (2) the development of sustainable photochemical rearrangements powered by visible light, and (3) implementation of computational tools for mechanistic prediction and reaction optimization This review serves both as an authoritative reference on fundamental mechanisms and as a strategic guide for future innovation, bridging the gap between theoretical understanding and practical synthetic applications in this rapidly evolving field.