UC Berkeley

This dissertation describes efforts toward the total synthesis of urceoloids A & B as a means to gain insight into the reactivity and synthetic utility of spiro[4.4]nonenes, an underexplored class of compounds.Chapter 1 introduces the field of total synthesis and highlights its growth, specifically noting the theme of exploration which carries through from its inception. We then discuss spirocyclic motifs in natural products and the strategies used to construct spirocyclic scaffolds. A brief history of spiro[4.4]nonenes is then provided, showcasing the limited investigations regarding their reactivity. Chapter 2 introduces urceoloids A & B and our motivation for total synthesis efforts toward these compounds. Additionally, we discuss our initial synthetic strategy which centers around an oxidative-Heck fragment coupling. Attempts at this fragment coupling led to the discovery of unexpected reactivity, which is the subject of Chapter 3. Chapter 3 outlines investigation of the unexpected rearrangement of a spirononene to enantioenriched, aryl-substituted annulated fulvenes. This work includes mechanistic insights which were performed in collaboration with the Houk group at UCLA. Chapter 4 captures the remainder of our total synthesis efforts toward urceoloids A & B. This work includes multiple revisions in strategy in order to ultimately achieve a successful fragment coupling between a spiro[4.4]nonene and cyclopentyl coupling partner. In the process of arriving at this success, we examined the reactivity of various spirocyclic intermediates and initiated investigations into the synthesis of enantioenriched spirocycles through an asymmetric iodolactonization. Overall, this combined body of work highlights how total synthesis may be used as a platform for exploration of underexplored structures and their reactivity.