Studies On The Asymmetric Total Synthesis Of Epi-6-DecarestricitineC₁, (+)-AspergillidesB, Cephalosporolide C, E And F

This dissertation aims at the studies on the asymmetric total syntheses ofanti-malarial epi-6-decarestricitine C₁, macrolide (+)-aspergillede B andcephalosporolide C, E and F. It consisted of the following four parts:Chapter 1. The construction of chiral pyran rings and the applications in naturalproducts syntheses (review)The recent development of construction of chiral pyran rings and application innatural products syntheses were briefly reviewed.Chapter 2. Facile total synthesis of anti-malarial epi-6-Decarestricitine C₁The isolation, bioactivity and structures features of decarestricitine family andsynthetic background of decarestricitine C were introduced briefly.A facile and effective synthesis of epi-6-Decarestricitine C₁ has been achievedfrom commercially available (S)-propylene oxide in 12% overall yield. The notablefeature of the synthesis was the use of reaction such as Sharpless assymetricdihydroxylation, aldol addition, Mitsunobu reaction and ring-closing metathesis(RCM).Chapter 3. Synthetic studies toward aspergillidesThe isolation, bioactivity, structures features and synthetic background ofaspergillide A-C were introduced briefly.A common strategy to synthesis of aspergillide B and C was investigated, whichwas applied to the synthesis of (+)-aspergillide B. Highlights of the synthetic ventureincluded the C-glycosylation reaction when constructing the 2,6-trans-disubstitutedpyrane core, a highly effective four-step sequence without purification to produce the key intermediate and an advantegous E-selective Julia-Kocienski olefination on ahighly elaborate substrate. As for our total synthesis, the longest linear sequencecomprised 12 steps involving a four-step sequence without purification and 9%overall yield.Chapter 4. Synthetic studies toward cephalosporolide C, E and FThe isolation, structures features and synthetic background of cephalosporolidefamily were introduced briefly.The introduction of three-component linchpin coupling reaction and the works ofour group in this area were described briefly.The advanced intermediate to the synthesis of cephalosporolide C, E and F wasachieved, which lay down a solid foundation for their total synthesis. The synthesischaracterized by use of three-component linchpin coupling reaction.