Date of Graduation
The replacement of the alkene moiety with an allene functionality in the intramolecular Pauson-Khand (P-K) cycloaddition provides a novel route to either Î±-alkylidene or 4-alkylidene cyclopentenones, depending on the substrate and reaction conditions. 1,3-Disubstituted allenes in the presence of molybdenum hexacarbonyl, DMSO, and toluene at 110Â°C give Î±-alkylidene cyclopentenones as a mixture of E and Z stereoisomers. The ratio of E and Z isomers is also dependent upon the substrate and the reaction conditions. 1,3-Disubstituted allenes are very useful precursors for the synthesis of complex chiral compounds with the allene serving as the stereocontrolling group. We have developed a method for the preparation of chiral Î±-alkylidene cyclopentenones using chiral 1,3-disubstituted allenes. In chapter 1, the synthetic utility of the chirality transfer process is examined by changing the R group on the terminus of the chiral allene and the ligands on molybdenum. Suberosenone (1) was isolated from the organic extracts of the gorgonian Subergorgia suberosa in 1995. Suberosenone has been shown to exhibit potent, differential cytotoxicity in the National Cancer Institute human tumor-based primary screen in ovarian, renal, and melanoma cell lines. Suberosenone, contains a unique tricyclic[4.3.2.01,5]undecane structure. This novel structure has been identified in only five other sesquiterpenes. An approach towards the synthesis of suberosenone is discussed in chapter 2.
Kerekes, Angela Dawn, "I. Chirality transfer in the allenic [2+2+1] cycloaddition reaction. II. An approach towards the synthesis of antitumor agent, (+/-)-suberosenone, using an allenic [2+2+1] cycloaddition reaction." (2000). Graduate Theses, Dissertations, and Problem Reports. 9166.