Saturated Cyclic Compounds of Sulphur and Selenium

The organization of this chapter is similar to that in previous volumes, with the exception that anion reactions, including those involving 1,3-dithian, have been omitted these are included in Chapter 2, Section 1. 

2 Thiolans, Thians, Thiepans, Thiocans, and their Oxides and Dioxides Synthesis.—The intramolecular trapping of a sulphenic acid by a carbon-carbon double bond constitutes a new stereospecific route to cw-2-substituted thiolans and thian 1-oxides. Thus 5-t-butylsulphinylpent-l-ene (1), when heated at 

in 74% yield, isomerically pure c/5-2-methylthiolan 1-oxide (3). The stereospecific formation of (3) results from a cw-addition of the intermediate sulphenic acid (2) to the double bond. 

Several other examples of this reaction have been provided, perhaps the most interesting being the formation of the bicyclic sulphoxide (5) upon thermolysis of di-t-butyl sulphoxide in the presence of cyclo-octa-1,5-diene. The unsaturated sulphoxide (4), obtained from the addition of t-butylsulphenic acid to one of the double bonds of the diene, was presumed to be the key intermediate. The isomerization, at 140 °C, of 2-methylthiepan 1-oxide to m-2-ethyIthian 1-oxide (35%) occurred via a cij-elimination to oct-5-enesulphenic acid followed by recyclization thiacyclo-oct-3-ene (32%) and bis(hept-6-enyl) disulphide were also formed in this thermolysis. 

Thietan 1-oxide has been found to react with Grignard reagents to give 2-substituted thiolans in fair yield. This unusual transformation appears to involve reduction of the sulphoxide function to a sulphide, with concomitant a-substitution, followed by a Lewis-acid-catalysed ring-enlargement reaction. 

Comparatively little new work has been reported with respect to saturated cyclic selenium compounds. A general treatise on organoselenium chemistry including various aspects of cyclic selenium compounds has appeared. The proceedings of a symposium on organoselenium chemistry have been published.  

2 Thiolansy Thians, Thlepans, Thiocans, and their Oxides and Dioxides 

Synthesis.—In general, the previously known methods of constructing sulphur-containing rings, such as intramolecular displacements by thiolate anions, intramolecular addition of thiol radicals to carbon-carbon multiple 

For example, the 3,4-dimethylenethiolan (2) was prepared in 60% yield by the reaction of (1) with Na2S. Oxidation of (2) gave the corresponding sulphoxide and sulphone all three compounds were fairly susceptible to polymerization. The sulphone could also be prepared in low yield by Zn-Cu couple reduction of 3,4-(dibromomethyl)sulpholene (4) in HMPA. As expected, the sulphone (3b) readily underwent Diels-Alder reactions 

Moreau, and A. Marquet, Bull. Soc. chim. France, 1972, 2299. 

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Saturated Cyclic Compounds of Sulphur and Selenium , T. Durst, in Organic Compounds of Sulphur, Selenium and Tellurium , ed. D. H. Reid, Royal Society of Chemistry, London, 1977, vol. 4, pp. 217-243 1975, vol. 3, pp. 139-218. 

Saturated Cyclic Compounds of Sulphur and Selenium, (CH2)4C02H... 

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