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Title: Synthesis and chemistry of novel bridgehead nitrogen compounds
Author: Montgomery, J.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2010
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Four isomers of pyridpyrrolizinones were made by FVP of the appropriately substituted pyrrole pyridine esters. The mechanism of the cyclisation is believed to follow the cascade mechanism. The structure of two of the ismoers has been confirmed by X-ray crystallography, the NMR properties of all four ismoers is also discussed in detail. The chemistry of 9-azapyrrolo[2,l-a]isoindol-5-one was also investigated, it was shown to undergo ring opening with LAH the product of which can then be repyrolysed to give a pyridopyrrolizine. Ring opening also occurs in methanol to give a nicotinate and the pyrrole ring can be hydrogenated to give a tetrahydropyridopyrrolizinone. The synthesis of pyrrolizin-l-one has been achieved by the FVP of methyl-3- (pyrrol-1-yl)-acrylate over W03 catalyst, the reaction is believed to proceed via an intramolecular electrophilic substitution reaction. The chemistry of pyrrolizin-l-one was investigated, reaction with nucleophiles proceeds via addition across the enone double bond. When a nitrogen nucleophile is used ring opening occurs. Hydrogenation occurs at the enone bond to give a dihydrpyrrolizin-l-one. Pyrrolinzin-l,3-dione was made by the oxidation of l-hydroxypyrrolizin-3-one using pyridinium dichromate. The dione shows ketone properties (eg. Formation of DNP derivative) and, in common with other pyrrolizinones, the lactam unit is readily ring opened by methanol under basic conditions. The active methylene unit of pyrrolinine-l,3dione couples readily with diazonium salts to provide a hydrazone whose structure was confirmed by X-ray crystallography. It also reacts with methoxymethylene Meldrum's acid to give a Meldrumsated pyrrolizine-l,3-dione whose FVP at 700 c gives a pyronopyrrolizinine. Reaction of pyrrolizine-l,3-dione with DMF acetal gives the 2-dimethylaminomethylene derivative which exists as a mixture of rotomers at room temperature. 8-Azaindolizine was made by FVP of DBN over a W03 catalyst. 8-Azaindolizine shows reactivity towards electrophiles in substitution reactions at the 3-position. It also reacts with methoxymethylene Meldrum's acid to give a Meldrumsated derivated whose FVP at 950 C reacts with 3-t-butyl-4-[l-methoxymethylene]-4H-isoxazol-5-one to give a isoxazolone whose FVP at 950 C gives a cyclazine.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available