Exploring Ring Transformation: Opening, Formation, and Swapping of Cyclic Structures

Recorded: April 2025

Presenter

Prof. Junichiro Yamaguchi – Department of Applied Chemistry, Waseda University, Tokyo

In this lecture, Prof. Junichiro Yamaguchi will discuss three unique transformations that dramatically alter cyclic skeletons. First, he will present a ring-opening strategy for cyclic amines. He discovered that exposure of cyclic amines to blue light in the presence of a Lewis acid and a photoredox catalyst leads to selective ring cleavage via carbon radical intermediates. This method offers a new avenue for breaking otherwise inert ring systems under mild conditions. Second, Prof. Junichiro Yamaguchi will discuss a ring-formation strategy via ortho-quinodimethane intermediates. By employing a simple multicomponent reaction, he generates highly reactive ortho-quinodimethanes, enabling the efficient construction of polycyclic structures. This approach provides a practical and modular platform for assembling complex ring systems. Finally, he will introduce his recent work on heteroaromatic swapping. During studies on the deacylative transformation of aromatic ketones, he uncovered a remarkably simple method to replace the aromatic ring with a heteroaromatic counterpart. This transformation proceeds via a Claisen/retro-Claisen pathway and represents a powerful tool for the selective editing of aromatic frameworks.