Base Metal-Catalyzed Cross-Couplings of Unconventional Oxygen-Based Electrophiles and Total Synthesis of Tubingensin A
- Author(s): Silberstein, Amanda Leanne
- Advisor(s): Garg, Neil K
- et al.
Transition metal-catalyzed cross-couplings provide a powerful means to assemble carbon-carbon (C-C) and carbon-heteroatom (C-X) bonds. Although halides are the most commonly employed electrophilic partner, phenolic derivatives offer a valuable alternative because phenols are typically inexpensive and readily available. This dissertation describes the development of cross-coupling reactions involving sulfamates and carbamates. Additionally, the total synthesis of tubingensin A utilizing a carbazolyne intermediate is reported.
Chapter one reviews the recent advances in transition metal-catalyzed alkylative cross-coupling reactions. This review considers primary and secondary alkylations, tertiary alkylations, and synthetic applications. Particular emphasis is placed on how modern methods have addressed historical challenges.
Chapters two and three describe the development of transition metal-catalyzed cross-coupling reactions to form C-C bonds. A nickel-catalyzed Suzuki-Miyaura cross-coupling of aryl sulfamates and carbamates is reported for the formation of sp2-sp2 C-C bonds. An iron-catalyzed Kumada coupling of aryl sulfamates and carbamates is reported for the formation of sp2-sp3 C-C bonds.
Chapters four and five pertain to the formation of C-N bonds. The nickel-catalyzed amination of both aryl sulfamates and aryl carbamates are dicussed. The synthetic utility of these methods is highlighted with the synthesis of linezolid, an antibacterial drug, and with sequential, site-selective carbamate and sulfamate cross-couplings.
Chapter six describes the total synthesis of natural product tubingensin A. The synthesis features an aryne cyclization to introduce the key vicinal quaternary centers and proceeds efficiently, in only nine linear steps.