Anodic Cyclization Reaction: Manipulation of Reaction Pathway and Efforts to Radical Cation and Radical Intermediate

In recent years, synthetic chemists have been expressing significant interest in electro-organic synthetic methods. This interest is being fueled by the existence of an increasing number of successful methods in the literature and the availability of new electrochemical equipment that removes the barrier to attempting an electrolysis reaction for the first time. Yet while these developments have fueled growth in some areas of electro-organic synthesis (the recycling of chemical catalysts for example), other areas remain underdeveloped. One such area is the exploration of reactions that can be triggered directly as an electrode surface without the use of any chemical reagent. Such reactions lead to highly reactive intermediates that allow for entirely new modes of reactivity to be explored. For example, our group has been working to develop anodic oxidation reactions that convert electron rich olefins into reactive radical cation intermediates. The reactions lead to a reversal in the polarity of the original olefin that enable the normally nucleophilic groups to be used as electrophiles. The result is an opportunity to change the entire manner in which the synthesis of a complex target is approached. Simply put, new modes of reactivity offer an opportunity to not only change the way individual steps in a synthetic sequence are conducted but also change the overall route because groups that normally function in a certain manner no longer behave the same way. While efforts to demonstrate the power of these opportunities have been successful for a variety of reactions in the group, our ability to continue forwarding the chemistry into even newer areas relies on our continuing to expand our knowledge of the reactive intermediates involved in electrochemical oxidation reactions, how they behave, and how they can be channeled down productive pathways. With this in mind, the main focus of this dissertation is to build our understanding of the reactive intermediates involved in anodic cyclization reactions and how those intermediates can best be applied as synthetic tools. The work probes the advantage of directly using the radical cations intermediates generated at an anode for triggering bond formation relative to pushing the reactions away from pathways that utilize the radical cation and toward pathways that involve an oxidative radical pathway. Along these lines, a synthetic route that allows both pathways to be accessed from the same starting materials has been developed. Using the chemistry, reactions that generate seven membered ring products and oxidative tandem cyclization reactions have been explored. In addition to these studies, an example of how optimizing a reaction sometimes requires one to pay attention to intermediates downstream of the cyclization is reported. Finally, the electrochemical method has been extended to an example of how it can be used in the synthesis of a complex molecular surface