Section I of this thesis is concerned with the rearrangement of allylic sulphinate esters to sulphones. Isomerisation of cyclohex-2-enyl toluene-p-sulphinate (1) and several related substituted sulphinates was investigated particularly in ionising solvents such as formamide. The substituted systems, 1-[<sup>2</sup>H]-cyclohex-2-enyl toluene-p- sulphinate and 3-methylcyclohex-2-enyl toluene-p-sulphinate (2), gave sulphones with the label scrambled between C-1 and C-3. Rearrangement of the conformationally biased esters, cis- and trans-5-t-butylcyclohex-2-enyl toluene-p-sulphinate, was not stereospecific. Sulphinate (1), both diastereoisomers of which reacted at the same rate, rearranged more slowly than did sulphinate (2). Rearrangement of sulphinate (1) in the presence of sodium benzenesulphinate lead to formation of some of the phenyl sulphone. A dissociative mechanism involving ion-pairs is proposed for the rearrangement of the above allylic sulphinates in ionising media. The [1,3] sulphonyl group migration of some allylic sulphones is discussed in Section II. 3-Methyl-3-(p-tolylsulphonyl)- 1-butene rearranged on heating in acetic acidwater (3:2 v/v) containing toluene-p-sulphinic acid or its sodium salt, and in this case slow rearrangement did occur in the absence of such additives. Substituted 3-(p-tolyl-sulphonyl)cyclohexenes rearranged in hot aqueous acetic acid containing sodium toluene-p-sulphonate, but were stable in the absence of added sulphinate. Under these conditions, epimerisation of cis- and trans-5-t-butyl-3-(p-tolylsulphonyl)- cyclohexene occurred at the same rate as deuterium was scrambled between C-1 and C-3 starting with 5-t-butyl-3-[<sup>2</sup>H]- 3-(p-tolylsulphonyl)cyclohexene. Benzenesulphinate was incorporated in a crossover experiment with 3-(p-tolyl-sulphonyl)cyclohexene. A chain addition - elimination mechanism involving either radicals or radical anions (an S<sub>RN</sub>1 process) is suggested for the [1,3] rearrangement of the allylic sulphones under the above conditions. Attempts to develop a stereospecific 5-membered ring annulation procedure involving allylic sulphones are described in Section III. As a model system, 1-(p-tolylsulphonyl)-1-vinylcyclopropane, prepared from 3-(p-tolylsulphonyl)propene, rearranged on flow pyrolysis to 1-(p-tolylsulphonyl)- cyclopentene.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:635168 |
| Date | January 1983 |
| Creators | Knight, Derek John |
| Contributors | Whitham, Gordon Harlow |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:64f41404-519b-4cd8-9426-1f3a8ebe717c |
Page generated in 0.0011 seconds