Part 1 Design, Synthesis, and Validation of Polymer-Supported Siloxane Transfer Agents for Transition-Metal-Mediated Cross-Coupling Reactions of Organolithiums Part 2 Total Synthesis of (-)-Mandelalide a Exploiting Anion Relay Chemistry

Part 1: Recent development of Anion Relay Chemistry (ARC) has revealed a “new ARC dimension”, namely the discovery of siloxane transfer agents for efficient palladium-catalyzed cross-coupling reactions of aryl and alkenyl lithium agents with aryl and alkenyl halides. Taking advantage of the direct use of organolithiums, the siloxane-based tactic holds the promise to eliminate the extra manipulation and purification steps required to generate other organometallic reagents as well as to avoid the heavy metal or main group waste streams observed in traditional cross-coupling reactions. Through rational design and synthesis, two generations of polymer-supported siloxane transfer agents were developed that simplify significantly product purification and transfer agent recycling. In addition to carbon-carbon bond formation, the transfer agent tactic was further applied in the construction of carbon-nitrogen bonds via a new copper-catalyzed electrophilic amination strategy. Part 2: This work described a highly modular, convergent total synthesis of the highly cytotoxic, scarce marine macrolide (-)-mandelalide A exploiting Anion Relay Chemistry tactic. The northern hemisphere was constructed via a new three-component type II ARC/CuCN cross-coupling protocol, while the southern hemisphere was secured via a highly efficient, four-component type I ARC union, both performed on preparative scale employing commercially available and/or readily accessible building blocks. This work showcases ARC as a powerful synthetic tactic for the rapid union of multiple, structurally simple starting materials to access diverse complex molecular fragments with excellent stereochemical control.