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Title: Investigations of new synthetic routes to fused tricyclic benzoheteropines
Author: Weddell, Iain A.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1992
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This thesis is concerned with the synthesis of fused tricyclic benzoheteropines by novel Friedel-Crafts type cyclisation reactions involving heterocumulenes. A general synthetic pathway was developed for the preparation of 1-[2-(3-methoxyphenoxy)pyrid-3-yl]-3-phenyl carbodiimide prepared in four steps from 2-chloro-3-nitro pyridine and 3-methoxy aniline. Studies were carried out into the optimisation of Lewis acid catalysis conditions for the successful intramolecular cyclisation of this carbodiimide to 9-methoxy-6-phenylaminopyrido[2,3-b][1,4]benzoxazepine and 7-methoxy-6-phenylaminopyrido[2,3-b][1,4]benzoxazepine. The extension of this methodology to the use of other carbodiimides was demonstrated by the preparation of 9-methoxy-6-methylaminopyrido[2,3-b][1,4]benzoxazepine from the readily prepared 1-[2-(3-methoxyphenoxy)pyrid-3-yl]-3-methyl carbodiimide. Investigations carried out into the cyclisation process showed that an electron donating group on the aromatic ring is essential for directing the successful ring closure to the benzoxazepine. It was found that the electronic nature of the carbodiimide had a marked effect on the efficiency of the cyclisation process. This was thought to have been due to a change in the electrophilicity of the carbodiimide. Thus electron donating groups immediately adjacent to the carbodiimide multiple bond were found to inhibit ring closure. Under the developed cyclisation conditions 9-methoxypyrido[2,3-b][1,4]benzoxazepin-6(5H)-one was prepared from the Friedel-Crafts type ring closure of 2-(3-methoxyphenoxy)pyrid-3-yl isocyanate. Likewise 9-methoxypyrido[2,3-b][1,4]benzoxazepin-6(5H)-thione was prepared from the corresponding isothiocyanate. The generality of the developed methodology to the synthesis of other fused tricyclic oxazepines was demonstrated by the analogous preparation of 3-methoxy-11-phenylamino-dibenz[b,f][1,4]oxazepine and 9-methoxy-6-phenylamino-pyrimido[4,5-b][1,4]benzoxazepine.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available