Date of Award
Doctor of Philosophy (PhD)
Chemistry & Biochemistry
Douglas L. Gin
The selectivity of the cross-metathesis reaction between electron-deficient polyenes and a general terminal alkene by use of different metathesis catalysts is presented. The reaction was found to be the most efficient when applied between a monoene or triene and the terminal alkene, providing the desired product in good to excellent yields. The selectivity is attributed to the reactivity of the terminal alkene of the triene which is furthest removed from the electron-withdrawing aldehyde or ester, rendering it the only alkene capable of reacting with the catalyst. Diene and tetraene substrates were not good partners in this reaction due to a lack of differentiation of the alkenes.
Different approaches toward the total synthesis of arenolide, a 14-membered macrolide with unclear stereochemical assignment and bioactivity, are also discussed. The first approach utilizes a 1,5-anti aldol reaction that was found to lack diastereoselectivity when applied to the total synthesis. The second-generation approach focuses on alternative methods to produce the 1,5-anti relationship between the alcohols at C9 and C13 with the exo-methylene group at C11. All studies include the use of a key intramolecular vinylogous aldol macrocyclization developed in the Sammakia lab, which was shown to be effective on a model precursor very similar to that of arenolide. Efforts are underway to complete the total synthesis of arenolide.
Arpin, Carolynn Chin, "Cross-Metathesis of Electron-Deficient Polyenes and Studies Toward the Total Synthesis of Arenolide" (2011). Chemistry & Biochemistry Graduate Theses & Dissertations. 49.