| This work revolves around the use of ketenes and their catalyst-derived enolates in the synthesis of a variety of synthetically useful and/or biologically active compounds. These reactive intermediates are formed via a unique, catalyst-driven, shuttle deprotonation system. [4+2] cycloaddition reactions between ketene enolates and o-benzoquinone derivatives will be examined. For example, the resulting cycloadducts from o-quinones and ketene enolates are readily converted to alpha-hydroxy esters through a simple, two-step ring opening and deprotection that can be conveniently performed in one pot. o-Benzoquinone imides are used as surrogates to form virtually enantiomerically pure alpha-amino acids and their derivatives. o-Quinone diimides form quinoxalinones in >99% ee, which are useful for drug development because of their structural relationship to benzodiazepines. This methodology is further developed through mechanistic studies and the introduction of a bifunctional catalyst system employing an achiral Lewis acid cocatalyst.;As a complement and a logical follow-up to our lab's previous work on cis-beta-lactams, the synthesis of trans-beta-lactams is then explored. A novel, anionic charged catalyst is examined for its utility in the diastereoselective synthesis trans-beta-lactams.;Despite their discovery over a century ago, ketenes remain interesting and challenging substrates to work with. In particular, monosubstituted ketenes are known to be excellent synthetic intermediates, although their instability can limit its uses. This dissertation focuses on the novel utilization of these flexible and potent compounds generated in situ through our shuttle deprotonation methodology. |
