UC San Diego

While classical alkene transformations have been known since the 1800s, the last 10-20 years have seen a renewed interest in providing transition metal catalysts to expand the diversity of alkene reaction partners. One important goal is selective isomerization of alkenes, to produce unique isomeric compounds that expand the scope of other synthetic transformations. In the past 11 years, the Grotjahn group has been at the forefront of the development of highly (E)-selective alkene isomerization catalysts; one that began with the discovery of the efficient catalyst 1.1 and continued with the development of more positionally selective catalyst 1.2 (& 1.2a). Catalyst 1.1 is currently sold commercially by Strem Chemicals, and has been used in a number of tandem and sequential processes to produce high-value compounds.

This dissertation details applications and modifications of existing Grotjahn catalysts (cyclopentadienyl)[2-(di-i-propylphosphino)-4-(t-butyl)-1-methyl-1H-imidazole]acetonitrile ruthenium(II) hexafluorophosphate (1.1) and (pentamethylcyclopentadienyl)[2-(di-i-propylphosphino)-4-(t-butyl)-1-methyl-1H-imidazole]acetonitrile ruthenium(II) hexafluorophosphate (1.2), along with its bisacetonitrile analogue 1.2a. The major goal that drives the direction of the dissertation include increasing the efficiency of 1.2 + 1.2a by developing a new version of the catalyst (discussed in chapters 3 and 4) that allows for dramatically increased reaction rates, and observation of the interactions of alkenes with this catalyst to understand more about the origins of selectivity and efficiency of this new catalyst. Other goals include determining the degree of the difference in selectivity between the new catalyst and existing Grotjahn catalysts, and increasing the scope of use of existing catalyst 1.1.