1,2,3-Trithiole

Photolysis of the 1,2,3-trithiole 42 in argon matrix (20 K) gave an electronic spectrum exhibiting the absorption maxima at 455 and 340 nm. Tlie spirodithiirane 43 and the thiosulfoxide 44 were believed to be responsible to these absorptions (89TL2955). 

Dithiazolyl radical 228 photochemically and thermally disproportionates to afford the 1,2,5-thiadiazole 229 and the unstable 1,2,3-trithiole 230 (Equation 54) <2000JCD3365>. Thermolysis of perfluoro-l,3A4(i2,2,4-benzodithiadia-zine 231 affords complex mixtures of heterocycles including perfluoro-2,l,3-benzothiadiazole 232 and 7,8-difluoro-benzo[l,2- 3,4-f ]bis[l,2,5]thiadiazole 233 (Equation 55) <2005EJI4099>. 

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. 

In the 1,2,3-trithiole series, 1,2,3-trithiole 2-oxide (29) was obtained in 39% yield from the reaction of 2,2-dimethyl-1,3,2-dithiagermole (112) with thionyl chloride (Equation (25)) <88RTC440>. 1,3,2-Dioxathiolane 2-oxide (8) is conveniently prepared by reaction of 1,2-dihydroxyethane with either thionyl chloride <66HC(2l-l)l> or dimethyl sulfite <76CRV747> (Scheme 26). An alternative method. 

A triplet state dimer of a benzofused 1,2,3-trithiole dication was postulated. However the occurrence of this high-spin dimer is strongly dependent on the nature of the solvent and the oxidant129. The 2,5-dimethoxy-4-methylphenyl moiety in which the additional charge and the single electron are stabilized in a quinoidal structure after one-electron oxidation has been utilized as a probe for electron delocalization when two of these moieties were connected either by a trimethylene, a 1,4-disubstituted phenylene or a biphenyl bridge130. 

Fast atom bombardment (FAB), as the name implies, involves bombarding a solution of the analyte in a matrix (most usually propane-1,2,3-triol, propane-1,2,3-trithiol, 2-nitrobenzyl alcohol or triethanolamine, Figure 5.4) with a beam of fast moving atoms, generally xenon atoms with energy in the range 6-9 keV (580-870 kJ mol ). 

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>. 

The synthesis of the stable 1,2,3-trithiole (120) has been reported by Tokitoh et al. <89TL2955>. The authors have photolyzed (120) in an argon matrix at low temperature while following changes in the electronic spectrum. This experiment revealed that two intermediates are formed, namely the 1,2-dithiete (121) and the thione (122). These intermediates are seen as forming from initial formation of thiosulfoxide (123) which is further transformed to the spirodithiirane (124) which serves as precursor to (121) and (122). 

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