Mailey and Ocone1'2 treated pyridine-l-oxide with hexafluoropropene and obtained 2-(l, 2,2,2-tetrafluoroethyl)pyridine in 44 per cent yield; the mechanism they postulated involved the formation of an isoxazolidine intermediate. This thesis forms a natural extension of their work, since the reaction has been applied to various 2-, 3-, 4-, 2.6- and polysubstituted pyridine-l-oxides and extended also to other heterocyclic N-oxides, namely those of 5-methylpyrimidine and quinoline. The N-oxides used are as shown below. The objectives of the investigations were to throw light on the proposed mechanism, to examine the generality of the reaction, and to obtain a number of fluorinated pyridine-N-oxides for testing as agrochemicals. Throughout the research it was found that some reactions gave only 'Mailey-and-Ocone' isolable products; e. g. 4-nitropyridine-l-oxide gave one tractable nongaseous product (A), whilst other reactions were considerably more complex, e. g. 3-bromopyridine-l-oxide gave four products (B) - (E)i that could not all be explained by the proposed (B) mechanism. During the course of this work, therefore, many new fluoroalkyl heterocycles were isolated inculding some unexpected compounds, another example being tetrahydrofuro(3,2-b)pyridine (F) from 2-ethoxypyridine-l-oxide. Many fluoroalkylpyridines formed in the above reactions were subjected to N-oxidation with peracids, and samples of the products listed below were sent for screening as potential agrochemicals.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:557102 |
| Date | January 1974 |
| Creators | Robinson, J. M. |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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