- Title
- Synthesis and conformational studies of indolizines
- Creator
- George, Rosemary
- Subject
- Indole alkaloids -- Research
- Subject
- Organic compounds -- Synthesis
- Subject
- Chemistry, Organic
- Date Issued
- 1994
- Date
- 1994
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- vital:4367
- Identifier
- http://hdl.handle.net/10962/d1005032
- Identifier
- Indole alkaloids -- Research
- Identifier
- Organic compounds -- Synthesis
- Identifier
- Chemistry, Organic
- Description
- The present investigation has involved a kinetic and mechanistic study of the thermal cyclization of 3-acetoxy-3-(2-pyridyl)-2-methylenepropanoate esters and related compounds to 2-substituted indolizines. Substrates for the kinetic study were prepared via the Baylis-Hillmann reaction of pyridine-2-carboxaldehydes with acrylate esters, acrylonitrile and methyl vinyl ketone. The resulting hydroxy compounds were then acetylated to afford the acetoxy derivatives, thermal cyclization of which gave the corresponding 2-substituted indolizines. The cyclization reactions was followed using 'H NMR spectroscopy and were shown to follow firstorder kinetics. The influence of the various substituents on the observed first-order rate constants has been examined and variable temperature studies have permitted evaluation of activation parameters for the formation of methyl indolizine-2-carboxylate and ethyl indolizine-2-carboxylate. An alternative route to 2-substituted indolizines via halogenated derivatives was explored and several halogenated 2-pyridyl derivatives were synthesised and their thermal cyclization to indolizines was attempted. Novel 5-methylindolizine-2-carboxamides were prepared as part of this investigation and dynamic NMR spectroscopy was used to study internal rotation about the amide N-CO bond in these compounds.
- Format
- 141 p.
- Format
- Publisher
- Rhodes University
- Publisher
- Faculty of Science, Chemistry
- Language
- English
- Rights
- George, Rosemary
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