"Transition Metal Catalyzed Ring Formation Reactions and a Mild Arene Hydrogenation Method" 

Many natural products and pharmaceuticals have complex polycyclic structures that present synthetic challenges. There are many powerful reactions (Diels-Alder, Pauson-Khand, Grubbs ring-closing metathesis, Wender arene-alkene photocycloadditions, and others), but new ring formations are always in high demand. For the last 20 years, my group has pioneered in the development of more than twenty new Rh-catalyzed ring-forming reactions. Applications of these new reactions in total synthesis has been demonstrated by us and by other research groups.

I will discuss the development and mechanistic elaboration of several transition metal-catalyzed reactions to construct difficult seven- and eight-membered rings, as well as applications of our [5+2+1] reaction for the synthesis of natural products. 

In the second part of the talk, I will describe our recent discovery of a new mild arene hydrogenation reaction that occurs at room temperature under 1 atmosphere of hydrogen gas, and this will provide a convenient approach to reach a variety of useful saturated six-membered rings in synthesis.