Thiirans Episulphides

Some of the more important monomers whose ring opening polymerisations have been induced by stable cation salts include, 1,4-epoxides, notably tetra-hydrofuran (20,112,113), 1,2-epoxides (114), 1,3-episulphides (thietans) (33,53), 1,2-episulphides (thiiranes) (53), azetidines (115,116), aziridines (117), the cyclic formals, 1,3-dioxolan (23,54, 118-120), and 1,3-dioxepan (118,119), trioxane (121,122) and more recently lactones (123). Aldehydes (124) may also be included since these molecules can be regarded as the smallest possible oxygen hetero-... 

SYNS AETHYLENSULFID (GERMAN) 2,3-DIHYDROTHIIRENE ETHYLENE EPISULHDE ETHYLENE EPISULPHIDE ETHYLENE SULPHIDE THIACY CLOPROPANE THIIRANE... 

These sulphur analogs of the 1,2-epoxides are variously known by the names thiiranes, thiacyclopropanes, alkylene sulphides, and episulphides. They are known to polymerize by the three catalytic mechanisms discussed for the oxygen compounds. Thus the same divisions are possible. For a discussion of some of the mechanistic aspects of these polymerizations as compared to epoxides, the reader is referred to a recent paper by Vandenberg [35]. 

Epimer A diastereomer having the opposite configuration at only one chiral centre Episulphide The sulphur equivalent of an epoxide, which is also called a thiirane. Episulphone A three-membered ring that contains two carbons and an S02 group. 

The epimeric forms of cholest-4-ene 2,3-episulphides and cholest-5-ene 2,3-episulphides have been prepared by established methods, but in a more unusual reaction deoxybenzoin reacted with thionyl chloride to give l,2-dibenzoyl-l,2-diphenylthiiran. The thiiran derivative (9) was formed photocatalytically from (10) as shown in Scheme 3, and in a more remarkable photochemical reaction (12) and (13) were both converted into... 

A new thiophen synthesis is based on deprotonation and cyclization of the resultant carbanion (65) of a keten dimethylthioacetal. Other applications of cr-(phenylthio)- or cr-(alkylthio)-alkyl-lithiums include preparations of disparlure (the sex pheromone of the gypsy moth) and other chiral epoxides,of an anti-peptic-ulcer diterpene from Croton sublyratus, of carbene-thiometal chelates through reaction with fCr(CO)gl or fW(CO)jl, of olefins via )ff-hydroxy-sulphides, and of Michael adducts of enones. In other work, the chiral solvent l,4-dimethylamino-2,3-dimethoxybutane is employed in enantioselective addition reactions of cr-thio-carbanions with ketones and Michael acceptors. a,P -Elimination of cr-thio-carbanions such as (66) provides a useful synthesis of olefins, and a 2-(lithiomethylthio)-A -oxazoline (67) has been used to prepare a C-labelled thiiran for a microwave study of the valence tautomerism of allene episulphide. ... 

The conversion of oxirans into thiirans by the action of sulphur nucleophiles has been further exploited, using thiourea or a thiocyanate. " Treatment of alkenes with (3) or (4), followed by reduction with L1A1H4, gives thiirans in good yields in a process that provides an alternative method for the conversion of alkenes into episulphides. Vicinal iodo-thiocyanates are converted into thiirans when treated with base. ... 

The thiiran groups of thia-tris-a-homobenzenes (37) and (38) are formed from the tris(oxiran) (36) via isothiouronium salts. Interconversion of epoxides into episulphides has also been reported in the carbohydrate series. ... 

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