Ruthenium catalyzed diol-diene cycloaddition and progress toward total synthesis of andrographolide
In the first chapter, an example of highly exo-selective ruthenium(0) catalyzed transfer hydrogenative cycloaddition is described. These ruthenium catalyzed reactions are analogous to traditional Diels-Alder reactions of cyclohexadiene or norbornadiene but are performed with 1,2-diols instead of the π-unsaturated partners. Novel bridged bicyclic ring systems are accessed from diol, ketol or dione oxidation level with excellent diasteroselectivity. In the second chapter, the ongoing efforts toward the total synthesis of andrographolide, a diterpenoid lactone, is described. The effort supports a modular strategy to use diene intermediate obtained from transformations of tert-hydroxy prenylation product via reaction with π-allyliridium C, O-benzoate complex.