Ligand Effect on Copper-Promoted Coupling Reactions: Analysis of Allenes as Pi-Bond Ligands; Synthesis and Applications of Substituted 1,3-Dienes and [n]Dendralenes
- Author(s): Cory, Brett Hart
- Advisor(s): Merlic, Craig A
- et al.
Chapters one and two focus on the effect of allenes as π-ligands on copper-promoted coupling reactions. While there are many examples showcasing alkenes and alkynes as π-bond additives in transition-metal reactions, allenes have no precedent as π-bond ligands, despite the similarities to alkenes and alkynes. The added benefit provided by allenes was observed in several different copper-mediated cross-coupling reactions. Chapter two will discuss the π-ligands role in these reactions through mechanistic studies.
Chapter three described a method for preparing substituted 1,3-dienes and [n]dendralenes. These privileged products are accessed through palladium(II)-catalyzed oxidative homocoupling of alkynes and internal vinyl boronate esters. The method is extremely mind and offers a wide range of functional group tolerance. A minor modification to the oxidative protocol conditions allows the synthesis of dendralenes through palladium(0)-catalyzed cross-coupling of alkynes and vinyl triflates. The utility of the diene products in synthesis will also be highlighted.
Chapter four will highlight the synthesis of cyclic triynes for use in the transannular hexadehydro-Diels–Alder reaction. The hexadehydro-Diels–Alder reaction has recently reemerged as a powerful way of accessing benzyne intermediates through an intramolecular [4+2] cycloaddition of an alkyne and a diyne. While there exists numerous examples for the intramolecular hexadehydro-Diels–Alder reaction, the transannular case has yet to be explored. Efforts towards understanding how ring strain effects the hexadehydro-Diels–Alder reaction will be discussed.