Please use this identifier to cite or link to this item: http://hdl.handle.net/2381/33925
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dc.contributor.authorStanton, Edward.en
dc.date.accessioned2015-11-19T08:47:41Z-
dc.date.available2015-11-19T08:47:41Z-
dc.date.issued1971en
dc.identifier.urihttp://hdl.handle.net/2381/33925-
dc.description.abstractThe main methods of generating heterocyclic amino-nitrenes are summarised and the subsequent fate of the nitrenes is considered. The photochemistry of three membered ring systems is reviewed. Certain 1-phthalimido- and 1 - (2-methylquinazol- 4-on-3-yl)-aziridines, when irradiated in the presence of an olefin, undergo an exchange reaction which produces a new aziridine incorporating the added olefin. Evidence is presented for a mechanism involving amino- nitrene formation by concerted cleavage of the aziridine C-N bonds. The scope of this reaction is delineated. Vapour phase flash pyrolysis of N-heterocyclic sulphoximides is used to generate amino-nitrenes under conditions such that nitrogen extrusion occurs. For example, phthalimido-nitrene gives benzocyclobutenedione and indazolyl-nitrene gives 1-cyanohexa-1, 3-dien-5-yne. Sulphoximides containing active protons ? to the sulphur atom and involving amide or imide heterocycles undergo a competing fragmentation to the parent amide or imide. Isoindolinyl-aziridines, prepared by reduction of the corresponding phthalimido-aziridines, are fragmented readily, possibly via isoindolinyl-nitrene. The possibility of intramolecular insertion of phthalimido-nitrene to give phthalaz-l,4-dione is upheld since the generation of the latter species by vapour phase flash pyrolysis of its Diels Alder adducts with dienes or its [2+2] adduct with indene is found to give benzocyclobutenedione. The retro Diels Alder reaction is also used to generate other reactive ?-carbonyl azo compounds in the vapour phase such that unimolecular decomposition then occurs. Thermolysis of 1-(quinazol-4-on-3-yl) -2-vinyl-aziridines gives the corresponding 3-(trans-but-2-en-1-ylideneamino) quinazol-4-ones in a novel rearrangement which is in competition with formation of 3-pyrrolines. At higher temperatures a fragmentation involving cleavage of the N-N bond also competes and this occurs to the exclusion of rearrangement in substituted vinyl-aziridines. An analogous fragmentation of trans-2,3-diphenyl-1-phthalimidoaziridine gives 2,3-diphenyl-2H-azirine, which in turn rearranges to 2-phenylindole. Reaction mechanisms are discussed.en
dc.language.isoenen
dc.rightsCopyright © the author. All rights reserved.en
dc.sourceProQuesten
dc.titleFragmentation and rearrangement in nitrogen heterocyclic chemistry.en
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePh.D.en
dc.date.award1971en
dc.publisher.departmentChemistryen
dc.publisher.institutionUniversity of Leicesteren
dc.identifier.proquestU378021en
dc.identifier.cataloguecontrolx753066296en
Appears in Collections:Theses, Dept. of Chemistry
Leicester Theses

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