Thiiran Oxides Episulphoxides and Episulphones

Lithium reagents desulphurize /ra s-2,3-diphenylthiiran 1-oxide, but give about equal yields of cis-stilbene and the lithium salt of stilbene-cf-sulphenic acid with cis-2,3-diphenylthiiran 1-oxide. Decomposition of the trans-isomer in the presence of ylides (53) leads to small yields of sulphines. Pyridine iV-oxide is deoxygenated by SO. In all these cases, kinetic measurements show that decomposition of the thiiran 1-oxide occurs independently of the substrate. 

An episulphoxide intermediate has been proposed in the thiophilic reactions of sulphines (see Chap. 3, Pt II, p. 162). The necessity of a pseudopericyclic process in the isomerization of tetrakis(trifluoromethyl)- Dewar thiophen 5-oxide has been questioned. Calculations of the electronic transitions of thiiran and methylthiiran oxides have been related to their u.v. and c.d. spectra.  

Episulphones are treated in a review of the pyrolysis of sulphones. A detailed analysis of the vibrational spectra of sulphones includes thiiran 1,1-dioxide.  

A molecular formula (54) appears in Chemical Abstracts as a product proposed to arise from the treatment of methyl oleate or methyl elaidate with sulphur at 140—160 °C. No details are available to the Reporter. 

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