Doctor of Philosophy (PhD)
Previous work in our laboratory has demonstrated not only a synthetic value of tandem reductive cyclization - carbonylation reactions in the preparation of complex molecules but also the interesting stereoselectivity observed therein. The first part of this work employs the titanium-mediated cyclocarbonylation of tethered dienals for the synthesis of prostaglandin analogues, in particular PGF2α and methyl jasmonate. Based on this hetero Pauson-Khand strategy, we have established an efficient racemic route to both the prostaglandin and the methyl jasmonate core skeletons. Moderate to excellent selectivities with regard to the hetero Pauson-Khand reaction were observed in both cases. The second part of our study leads towards the novel synthesis of the biologically active α-methylene-γ-butyrolactone moiety via titanium mediated hetero Pauson-Khand reaction of allenic aldehyde/ketone substrates. This substructure is embodied in many natural products such as Sarkomycin and Frullanolide which have excellent antibacterial and anticancer activities. The final part of this study describes the development of the titanium-mediated reductive cyclocarbonylation and an imino-alkyne cross-metathesis strategy towards the synthesis of pyrrolizidine and indolizidine alkaloids respectively. The same substrates were employed in both reaction pathways.
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Appeaning, Maria A., "Applications of titanium-mediated reductive coupling and cyclocarbonylation reactions toward natural product synthesis" (2006). LSU Doctoral Dissertations. 858.