Guiding excited state reactivity – the journey from the Paternò–Büchi reaction to transposed and aza Paternò–Büchi reactions

Chromophores embedded in a given molecular structure often exhibit different excited state properties. Therefore, molecular design becomes very critical to explore the fundamentals of the excited state processes and tailor their reactivity. Related to this we highlight how molecular skeletons can be utilized to control excited-state reactivity and how new/novel reactivity can be uncovered through rational molecular design. The history of photochemistry clearly showcases that chemists continue to strategically design molecules to understand the reactivity of various chromophores such as alkenes, carbonyls and imines. Here we will highlight our group’s effort in designing molecular structures and tailoring excited state transformations such as [2+2] photocycloadditon reactions, the Paternò–Büchi reaction, and transposed and aza Paternò–Büchi reactions.