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Title: The synthesis and properties of electron-rich and electron-deficient 3-hydroxypyrroles and 3-hydroxythiophenes
Author: Morrow, Mark
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1994
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A number of new 5-aminomethylene and 5-thiomethylene Meldrum's acid derivatives have been prepared. A detailed study of their X-ray crystal structures was carried out and it was found that the formal carbon-carbon double bond is strongly twisted with unusually long bond distances. Furthermore a linear relationship was found to exist between the twist angle and the C=C bond length for a number of examples. Reactions of these derivatives with organometallic reagents are also reported. The flash vacuum pyrolysis of Meldrum's acid derivatives to give new examples of 3-hydroxypyrroles and 3-hydroxythiophenes with electron-donating and electron-withdrawing substituents in the 5-position is described. The effect of these substituents on the reactivity and regioselectivity towards alkylation, acylation and electrophiles was also examined. Detailed NMR spectroscopic studies were carried out on the products which were prepared and a number of crystal structures were obtained. Facile reactions of 3-alkoxypyrroles with n-butyllithium were found to occur regiospecifically in the 2-position. The 2-lithio derivatives which were formed were subsequently reacted with a range of reagents which enabled the introduction of further electron-donating or electron-withdrawing substituents in the 2-position. The formation of 7-hydroxy-1-methoxypyrrolizin-3-one and/or 7-methoxy-pyrano[3,2-b]pyrrol-5(1H)-one from the novel pyrolysis of 5-[1-(4-methoxy-2-oxo-3-pyrrolinyl)]methylene Meldrum's acid is described for a range of furnace temperatures. A mechanism is proposed for the formation of pyrrolizin-3-one and its subsequent rearrangement at high temperatures to give the pyranopyrrole.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available