City Research Online

Abstract

The chemistry of vinyl sulphoxides and the rearrangement of allylic sulphoxides to allylic sulphenates are reviewed.

The base-catalysed condensation of α -sulphinyl esters with aldehydes has been developed into a useful synthesis of α - sulphinyl α, β -unsaturated esters and the geometry of the double bond in these products has been established as E by means of the europium-shifted n.m.r. spectra. It has been established that the pyridine-induced rearrangement of these unsaturated sulphoxide esters leads clearly to E-Y-hydroxy- α, β -unsaturated esters. The rearrangement of an α -sulphinyl dienoic ester has also been examined in detail.

The condensation of methyl benzenesulphinylacetate with crotonaldehyde in the presence of magnesium methoxide was found unexpectedly to lead to sequential formation of α -sulphinyl dienoic ester, Michael attack of methoxide ion and allylic sulphoxide-sul-phenate rearrangement. This observation was turned to advantage by developing a * one-pot* procedure for the synthesis of E-Y-hydroxy- - α, β -unsaturated esters, utilizing the magnesium methoxide-induced condensation of α -sulphinyl esters with aldehydes. Conjugate addition of nucleophiles other than methoxide to the α -sulphinyl dienoic ester derived from crotonaldehyde was also investigated.

Having established a convenient synthesis of α -sulphinyl α, β -unsaturated esters, the value of these compounds as synthons has been demonstrated by their use in Diels-Alder reactions. The Claisen rearrangement of an allylic α -benzenethioacetate, followed by a sulphoxide elimination reaction was explored for stereospecific olefin synthesis.

In order to exemplify the use of the condensation of aldehydes with α -sulphinyl esters and the subsequent allylic sulphoxide-sul-phenate rearrangement, the application of these reactions to the synthesis of the macrolide pyrenophorin has been explored at length.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science Q Science > QD Chemistry
Departments:	School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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