I. I. DEVELOPMENT OF DONOR-ACCEPTOR CYCLOPROPANES FOR THE PREPARATION OF COMPLEX TETRAHYDROFURANS II. APPLICATION OF RHODIUM CATALYSIS TO THE STEREOSELECTIVE SYNTHESIS OF CYCLOHEXANES AND GLYCOLATES

Donor-acceptor cyclopropanes are unique strained compounds that have been studied extensively toward the synthesis of valuable heterocyclic compounds. We investigated a two-step sequence to spirocyclic heterocycles involving an initial cycloaddition of an alkylidene cyclopropane followed by Lewis acid catalyzed annulation of the cyclopropane with an array of electrophiles. Secondly, the potential for α-keto esters to serve as acceptor groups in donor-acceptor cyclopropane annulations was explored. This led to the development of a copper-(II) catalyzed annulation of these cyclopropanes with aromatic aldehydes that proceeded with good diastereoselectivity.An asymmetric dearomatization of benzenoid compound was achieved by an enantioselective arene cyclopropanation using α-cyanodiazoacetates under the action of Rh2[(S)-PTTL]4 as a catalyst. The enantioenriched norcaradienes were subsequently functionalized via cycloadditions with a multitude of dienophiles and direct diene functionalization via dihydroxylation. Benzene norcaradienes were desymmetrized by epoxidation and the products elaborated to complex cyclohexanes with high stereocomplexity.A rhodium-(I) catalyzed addition of arylboronic acids to silyl glyoxylates was developed. Direct addition followed by enolate protonation/deuteration afforded mandelate products in good yield. Both racemic and asymmetric three-component couplings of arylboronic acids, silyl glyoxylates and aldehydes were developed, representing a rare instance of intermolecular three-component reactions where two carbon-carbon bonds are formed in a controlled sequence.Doctor of Philosoph