Studies On The Asymmetric Total Syntheses Of(+)-Neopeltolide,Cyanolide A And Iriomoteolide-1a(-1b)

This thesis mainly focused on the total syntheses of biologically important marcolides. Studies toward total syntheses of (+)-Neopeltolide, Cyanolide A and Iriomoteolide-1a (-1b) were described. It consisted of the following four parts:Chapter 1. The development of palladium(II)-catalyzed alkene functionalization. (Review)Described the development of palladium(II)-catalyzed alkene functionalization and the applications in natural products'syntheses.Chapter 2. Concise Formal Synthesis of (+)-Neopeltolide.A concise formal synthesis of (+)-neopeltolide has been achieved in 12 steps (longest linear sequence) and 18% overall yield from commercially available L-valinol. Notable features include:high atom economy with minimized protective group manipulation, iridium-catalyzed double asymmetric carbonyl allylation, palladium-catalyzed intramolecular alkoxycarbonylation, ruthenium-catalyzed olefin isomerization and ring-losing metathesis.Chapter 3. Total Synthesis of Cyanolide A.An enantioselective total synthesis of cyanolide A (1) has been achieved with the longest linear sequence of 14 steps. Central to this venture was the efficient palladium-catalyzed intramolecular alkoxycarbonylation to construct the tetrasubstituted cis-tetrahydropyran ring core with high stereoselectivity.Chapter 4. Studies Toward Syntheses of iriomoteolide-la and-1b.A stereo selective synthesis of C13-C23 subunit of iriomoteolide-la (-1b) has been achieved, exploiting the asymmetric aldol reaction and the Julia-Kocienski olefination as the key steps. In order to reduce the cost of the synthesis we adopted usual reactions and used inexpensive reagent through the synthesis strategy.