1,2,4-Trithiolane

Heating or irradiating alkenes in the presence of sulfur gives relatively low yields of thiiranes. For example, a mixture of sulfur and norbornadiene in pyridine-DMF-NHa at 110 °C gave a 19% yield of the monoepisulfide of norbornadiene as compared with a 78% yield by the method of Scheme 120 (79JCS(Pi)228). Often 1,2,3-trithiolanes are formed instead of thiiranes. The sesquiterpene episulfides in the essential oil of hops were prepared conveniently by irradiation of the terpene and sulfur in cyclohexane (Scheme 135) (80JCS(Pl)3li). Phenyl, methyl or allyl isothiocyanate may be used as a source of sulfur atoms instead of elemental sulfur. 

The unusually stable cross-ozonide 89 has been reported <06TA1780>, and a range of isomeric mono- and disulfoxides of the E-cyclooctene-derived 1,2,3-trithiolane 90 have been prepared <06T5441>. 

Significant advances in the chemistry of these ring systems over the past 10 years include the first unambiguous detection, and characterization by microwave spectroscopy as 1,2,3-trioxolane, of the primary ozonide from ethene and ozone (cf. Section 4.15.3.2), and the introduction of 1,3,2-dioxathiolane 2,2-dioxides as epoxide equivalents in organic synthesis (cf. Section 4.15.5.3). Advances have also been made in the synthesis and characterization of the chemistry of 1,2,3-trithiolanes and 1,2,3-trithioles. 

Table 1 Structural parameters of derivatives of 1,2,3-trithiolane, 1,3,2-dioxathiolane and 1,2,5-oxadithiolane and some unsaturated counterparts, obtained by x-ray or ... 

It has been suggested that the oligomers and polymers formed in the ozonolysis reactions of some alkenes arise from the reactive 1,2,3-trioxolane intermediates or their fragmentation products (cf. Section 4.15.4.1) , though relatively little is known about the mode of formation of many of these polymeric species. The tendency of simple 1,2,3-trithiolanes to polymerize has... 

Some derivatives of 1,2,3-trithiolane have been used as starting materials for sulfur-containing polymers <84MI 4l5-0l>. Industrial applications for 1,2,3-trithiolane derivatives include their use as high-pressure lubricant oil additives <88EGP258606>, plasticizers and antioxidants <89EGP263770>. 

There are six possible five-membered monocycles 1-6 containing three oxygen or sulfur atoms in the 1,2,3-positions <1996CHEC-II(4)545>. 1,2,3-Trioxolane 1 is the parent compound of the so-called primary ozonides, the primary reaction products in the reaction of alkenes with ozone. They are extremely unstable and rearrange to the more stable ozonides (1,2,4-trioxolanes). This rearrangement represents a key step in the reaction of ozonolysis. However, the parent compound 1 and a few derivatives have been characterized at low temperatures (see Section 6.05.10.1). 1,2,3-Trithiolanes have been synthesized (Section 6.05.10.3) some of them undergo slow decomposition at room temperature. Derivatives of 1,2,3-dioxathiolane 3 are unknown, and the other heterocycles of the mixed types 4-6 are known only in the oxidized forms, mostly as -oxides and J -dioxides, and also A-imino and A-thiono derivatives <1996CHEC-II(4)545>. The A-oxides and AA -dioxides of... 

Monosubstituted 1,2,3-trithiolanes 58 (R = Me, Ph) were obtained in 91% and 90% yield, respectively, by a disproportionation of the corresponding episulfides catalyzed by the ruthenium complex 57 (Equation 18) <2002JA4770>. 

Norbomene reacts with elemental sulfur to give a mixture of 1,2,3-trithiolane 59 (R = H) and pentathiepane (Equation 20) <2005TL7077>. The use of Ni(NH3)6Cl2 in DMF as a catalytic system allowed the selective transformation of norbomene and its derivatives into -l,2,3-trithiolanes 59 in good yields (75-82%). The reaction selectivity was maximal at an alkene Ss ratio of 1 3/8 <2005TL7077>. 

In another electrochemical experiment, the sacrificial sulfur/carbon electrode was a source of cations S2+, which reacted in organic media with thiols or thiolates to give polysulfides, for example, 1,2,3-trithiolane (11%) <1996BSF273>. 

Trithiolanes are not known to undergo thermal rearrangement like 1,2,3-trioxoIanes but tend to polymerize (cf. Section 4.33.3.1.4). At elevated temperatures they decompose... 

The few known monocyclic 1,2,3-trithiolanes have proved to be rather unstable compounds with a marked tendency towards polymerization. Thus simple alkyl-substituted... 

Trithioles and 1,3,2-dioxathiolanes. 1,2,3-Trithiolanes are prepared by reaction of alkenes with elemental sulfur . The synthesis of 1,3,2-dioxathiolane -oxides (cyclic sulfites) and 1,3,2-dioxathiolane S, -dioxides (cyclic sulfates) is discussed in comprehensive reviews <1997AHC(68)89, 2000T7051>. The most widely used method for the preparation of 1,3,2-dioxathiolane A-oxides 557 is the reaction of the corresponding 1,2-diols 556 with thionyl chloride in the presence of pyridine or triethylamine (Scheme 251). More reactive 1,3,2-dioxathiolane S,A-dioxides 558 are usually obtained by oxidation of sulfites 557 with sodium periodate, which is mediated by ruthenium tetroxide generated in situ from a catalytic amount of ruthenium trichloride <1997AHC89, 2000T7051, CHEC-III(6.05.10.3)183>. 

Heating of norbomene, dicyclopentadiene (DCPD) or tricyclopenfadiene with elemental sulfur in DMF in the presence of NH3 or friethylamine also produces the corresponding 1,2,3-trithiolane derivatives in yields of 20 85%. For the reaction of hquid sulfur with DCPD, see Section 7. A careful investigation of the reactions of sulfur with norbomene, norbomadiene, and DCPD showed that tri-and pentasulfanes are formed and may be isolated as pure materials in the case of norbomene these are in equilibrium in solution at 20 °C (equation 91). ... 

The formation of the 1,2,3-trithiolane (11) has also been observed when norbomene was heated with ben-zopentathiepin, 1,2-6611485, in DMF in the presence of triethylamine (yield 48%, at 100 °C) (equation 95). Ben-zopentathiepin, heated in the presence of R3N, apparently... 

Ruthenium salen nitrosyl complexes react catalytically with thiiranes and convert them to olefins and 1,2,3-trithiolanes 163 (Scheme 34) or 1,2,3,4-tetrathianes 164 (Scheme 35) <2001JA4770>. 

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