Physical Properties and Theoretical Treatments

Ab initio MO-SCF calculations have been done for thiiran, thiiran 1-oxide, and thiiran 1,1-dioxide. Variations in carbon-carbon bond distances are 

Formation.— The methods of synthesis of thiirans have been reviewed. A brief discussion of the preparation of thiirans is part of a review on the reactions of alkali-metal sulphides with organic halides and toluene-p-sulphonates.  

Yamabe, H. Kato, S. Nagata, and K. Fukui, Bull. Chem. Soc. Japan, 1975,48,33. 

Thiirans are obtained in good yields (61—78%) by treatment of aldehydes and ketones with the lithium salt of 4,4-dimethyl-2-(methylthio)-A -oxazoline (4). Other sulphur-stabilized carbanions may similarly be used, e.g. the lithium salts of 2-(alkylthio)thiazolidines, 2-(benzylthio)pyridine, and benzyl diethyl-dithiocarbamate.  

Adamantanethione was converted into a thiiran by addition of a methylene group, derived from methylenetriphenylphosphorane, across the carbon-sulphur double bond. The action of Grignard and other organometallic reagents on thiones gives thiirans together with other products, and thiirans also are obtained by treatment of 3-piperidino-2-phenylindene-l-thione with several diazoalkanes.  

Moderate yields (26—57%) of thiirans are obtained directly from olefins, e.g. (1), on treatment with iodine-thiocyanogen, followed by hydrolysis of the thiocyanate (2) so formed and the displacement of iodide ion. The 

Further investigations into the reacti m of sulphur atoms with olefins to yield thiirans have established absolute rate constants and a n ative temperature dependence on the rate constants for the reaction of sulphur in its state, obtained by flash i otolysis of carbon oxysulphide, with 

Thiirans are said to be obtained in high yields by thermolysis (215—250 °C) of mercaptoalkyl acetates over alumina. Cyclization of chloro-mercaptocarboxylic acid derivatives gave derivatives of thioglycidic acid. 3-Aryl-2,2-dicyano-oxirans failed to give thiirans with thiourea instead, 2-amino-4-oxo-5-aryl-2-thiazolines were obtained. The thiourea method, however, is in general use.  

Karimova, M. G. Linkova, O. V. Kfldisheva, and I. L. Knunyants, Izvest. Akad. Nauk 

The reactions of thioketones, thiono-esters, and dithio-esters with diazoalkanes yield thiirans (6) and often the olefinic product (7) formed by 

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