Olefin metathesis: A versatile tool for the synthesis of small to large molecules

In olefin metathesis, the designing of better catalysts has been the key to the success of its utility. Throughout the history of olefin metathesis research, the development of new and improved catalysts has brought new applications and new structures that are accessible by olefin metathesis routes. With the development of highly active catalyst containing an N-heterocyclic carbene, the field of olefin metathesis is currently in a period of renaissance opening up the versatile synthesis of both small organic molecules to macromolecules. Following four chapters describe recent applications toward the synthesis of molecules with various sizes.; Chapter 2 describes selective CM of various of alpha,beta-unsaturated carbonyl compounds such as acrylic acid, acrylic amides, and vinyl phosphonate with terminal olefins and stryenes. For CM of acrylic amides, an interesting chelation effect which reduced the olefin metathesis activity of the catalyst containing an N-heterocyclic carbene was observed for electron rich amides. Also direct generation of enoic carbenes by catalyst was possible from acrylates, acrylic acid and vinyl ketones. Enoic carbenes were shown to catalytically ring-open cyclohexene for the first time. Chapter 2 also provides examples of challenging CM between Type II and Type III olefins.; Chapter 3 demonstrates facile tandem RCM strategies to rapidly synthesize complex small molecules by the catalyst containing an N-heterocyclic carbene. Tandem ring-opening/ring-closing metathesis and tandem enyne RCM provided bicyclic compounds with good yields. An example of bicyclic macrocycle is presented. Lastly tandem ring-opening/cross/ring-closing metathesis, also known as ring expansion metathesis (REM), provided a convenient route to various macrocycles from the smaller cycloalkenes.; Chapter 4 introduces a new concept of metathesis polymerization, multiple olefin metathesis polymerizations (MOMP). MOMP uses more than one olefin metathesis process to synthesize polymers with uniform polymer microstructures. Ring-opening insertion metathesis polymerization (ROMMP) combines ROMP and CM process to yield highly A,B-alternating copolymers. Also ring-opening/ring-closing polymerization and ring-opening/closing addition polymerization were demonstrated.; Final chapter explores living ROMP of norbornene and its derivatives with a new ultra-fast-initiating catalyst. The modified catalyst produced the polymers with very narrow PDI and the monomers which used to be problematic with the previous catalysts also underwent living ROMP. Also amphiphilic block copolymers were prepared and shown to undergo spontaneous self-assembly in the reaction solution to produce stable nanoparticles even without cross-linking. Nanoparticles of 10 to 50 nm in radius were characterized by GPC, DLS and SEM.; In summary, this thesis describes the versatility of ruthenium catalysts being able to produce small molecules, macrocyles, polymers, and even supramolecules. Molecules that are described in the thesis have molecular weights ranging from 100 to 2 million g/mol, and the reactions to prepare those molecules with various sizes are fundamentally and mechanistically one transformation, the exchange of C=C bonds. This is a success story of how interdisciplinary efforts from organic, organometallic, and polymer communities have brought the new concept to chemical synthesis.