The work described herein is directed towards the Claisen rearrangements and [3+2] cycloaddition reaction of pyridine N-oxide systems. The pyridine N-oxide molecule is a very versatile and useful synthetic intermediate for the construction of more complex pyridines. Chapter 1 contains a review of work carried out within the group towards Claisen rearrangement of benzene-type systems. The acid catalysed rearrangement of these systems affords a high degree of regioselectivity. A literature survey of the [3+2] cycloaddition reaction of both aliphatic nitrones and aromatic N-oxides with various dipolarophiles is also included. Access to many stereochemically pure products demonstrates that the [3+2] cycloaddition has become a very important ring-forming reaction. Chapter 2 describes development of two Claisen rearrangement precursors and their subsequent attempted Claisen rearrangement is outlined. Chapter 3 details the construction of a range of 3-substituted pyridine N-oxides. Their attempted intermolecular cycloaddition, by thermal means and at high pressure, with mono- and di-activated dipolarophiles is described. Chapter 4 outlines attempts towards and the final synthesis of the ester cycloaddition precursors. Attempted intramolecular [3+2] cycloaddition of these substrates both thermally and under high pressure is summarised. Chapter 5 describes approaches towards [3+2] cycloaddition precursors that contain mono- and di-activated dienophiles. The synthesis of a variety of 3-substituted pyridines is detailed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:308591 |
| Date | January 1995 |
| Creators | Knott, Jane Marie |
| Contributors | Harwood, Laurence M. |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:cc74d06b-9840-4695-9f47-961583da147c |
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