Investigations into the selectivity of olefin cross-metathesis using ruthenium alkylidene catalysts: Electronic and steric matching of substrates

Olefin cross-metathesis (CM) is a thermodynamically controlled metathesis reaction that is governed by statistical product distributions and a mixture of olefin stereoisomers. In fact, while the reaction allows for the functionalization of alpha-olefins under mild conditions, it has not been used widely due to a lack of selective processes. The research effort disclosed here has provided some new solutions to the selectivity issues involved with CM. These include the use of olefins with altered steric and electronic properties allowing for selective olefin functionalization by CM. After an introduction to state-of-the-art CM in Chapter 1, the discussion continues with CM work in earlier generation ruthenium catalyst systems (Chapter 2). The next two chapters reveal new substrate scope in CM using more active ruthenium based catalysts developed in this group, including the synthesis of trisubstituted olefins (Chapter 3) and directly functionalized olefins (Chapter 4). Once discoveries in expanding substrate scope were accomplished, the final chapter outlines an empirical model for understanding the electronic and steric factors in CM selectivity across a variety of olefin metathesis catalysts. This model also provides a method to determine whether selective CM can be performed for target-oriented synthetic efforts. In addition, a better understanding of selectivity issues allows for the discovery of new reaction platforms and expands the synthetic utility of CM is discussed in Chapter 5.