The application of organocatalytic Asymmetric Epoxidation

Alahmdi, Mohammed (2014) The application of organocatalytic Asymmetric Epoxidation. Doctoral thesis, University of East Anglia.

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In the field of research of target natural product synthesis, catalytic asymmetric synthesis has
become a vital tool to obtain enantiomerically pure compounds, and is often used in the
synthesis of natural products as a key step.1 For example, the asymmetric dihydroxylation
was used in synthesis of gibberellic acid (GA3)2 by E. J. Corey, who was awarded the Nobel
Prize for his developments in the theory and methodology of organic synthesis.2
This thesis is based on an ongoing research in the area of catalytic asymmetric synthesis that
has been carried out in our group. Since 2005, metal-free catalytic asymmetric epoxidation
using iminium salts such as 1 has been successfully employed to access chiral chromenes
within the Page group. Iminium-catalysed asymmetric epoxidation methodology has been
applied to the synthesis of levcromakalim, 3 trans-khellactone, and lomatin,4 which are based
on a chromene-type structure. In this thesis, we offer a detailed discussion on the influence of
iminium salts on flav-3-ene derivatives and their stability under oxidative conditions. We
were also able to successfully apply our methodology towards the enantioselective total
synthesis of (3S,4R)-trans-3,4-dihydroxy-3,4-dihydromollugin 2. The key epoxidation step
proceeded in 70.4% ee and high yield, using chiral iminium salt catalyst 1 under aqueous
conditions. The acid-catalysed epoxide ring-opening of epoxide 4 afforded trans-diol 3 in
high yield.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Users 2259 not found.
Date Deposited: 17 Oct 2014 11:55
Last Modified: 17 Oct 2014 11:55


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