Progress toward Lewis acid catalyzed asymmetric transformation of amino alcohols towards influence on the Blakey group synthesis of malagashanine Open Access

Davies, Geraint Hywel Madoc (2012)

Permanent URL: https://etd.library.emory.edu/concern/etds/xg94hq408?locale=en
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Abstract


This honors thesis describes the exploration of the asymmetric nucleophilic allylation of a
N-tosyl iminium ions by ion pairing initiated by a chiral Lewis acid catalyst. The studies
were inspired by their potential application to the natural product synthesis of
malagashanine. Through selective catalyst manipulation, we look to make catalyst ligand
modifications that could tune the reactivity and selectivity of the Lewis acid. From this
project we hope to be able to expand the scope of this catalyzed system and develop a
greater understanding to the mechanism of the catalytic pathway. This information should
enable a suitable reaction system to positively enhance the critical cascade reaction step of
the malagashanine core molecule.

Table of Contents

Table of Content

1. Introduction.........................................................................1

a. Malagashanine........................................................................1

b. Lewis Acid Catalyzed Allylation..................................................2

2. Chapter 1: Stereoselective titanium catalyzed allylation.......3

a. Introduction............................................................................3

b. Ligand Synthesis.....................................................................5

c. Ligand Modifications.................................................................7

i. Modification to the Grignard agents

ii. Modification to the amino methyl ester

d. Test Substrate Synthesis..........................................................9

i. Synthesis of hydroxy methylindane

ii. Synthesis of TMS protected piperidinol

e. Aidi's Work............................................................................11

i. Problems reproducing the published catalytic allylation reactions

ii. New Lewis acid metal and ligand screen

3. Chapter 2: Bifunctional Catalysis.........................................14

a. Introduction...........................................................................14

b. Test Substrate........................................................................15

i. Synthesis of test substrate

ii. Racemic allylation

c. Catalyst Scaffold.....................................................................18

i. Catalyst synthesis

4. Future Work........................................................................20

5. Conclusion...........................................................................21

6. Experimental.......................................................................22

7. References..........................................................................30

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