Dithiolium

Certain dithiolium salts have been reported by Leaver and Robertson to form isothiazoles on treatment with ammonia thus, 3,5-diphenyl-l,2-ditholium perchlorate (15) gives a 50% yield of 3,5-diphenylisothiazole (16). The method does not appear to be generally applicable, and the analogous 3-methyl-5-phenyl-l,2-dithiolium salt did not give an isothiazole. 

Reaction of Cyclopentadienides or Their Nitrogen Analogs with Azolium and Dithiolium Salts... 

One decade later, the parent compounds 21 were synthesized (78BCJ1427). For example, the reaction of 2-methylthio-l,3-dithiolium iodide with pyrrole gave 2-(2-pyrrolyl)-l,3-dithiolium iodide in a 92% yield, which on treatment with DBU gave 5-aza-l,4-dithiafulvalene 21 (R = H, Z = S, no Ph at dithiole-ring) as thermally stable orange crystals. Using the same type of reaction, the benzoderivatives of type 24 could be isolated (78BCJ1427). 

A considerable extension of that method was reached by the condensation of 1,2- and 1,3-dithiolium- 1,3-thiaselenium- and 1,2,4-thiadiazolium salts with pyrroles, 2- or 4-phenyl- 2,4-diphenyl- and 4,5-diphenyl imidazoles (70TL481). At room temperature and in acetonitrile solution some of... 

Similarly, indole itself could be converted by 2-methylsulfanyl-l,3-dithiolium iodide to its 3-dithiolium derivative, which gave 27 quantitatively with DBU. However, treatment of indoles, which bear the benzo-dithiolium moiety in the 2-position with tertiary amines, resulted in a black reaction mixture. All attempts to isolate the o-quinoid compound 28 failed (Scheme 7). 

Tlie interest in the preparation and use of dithiolium salts in connection with the synthesis of TTF derivatives led to the development of a new uses of heteroaromatic cations in organic synthesis. Based on that, a new carbonyl olefination for the synthesis of numerous heterofulvalenes was developed (77S861). For example, 2-dimethoxyphosphinyl-l,3-benzodithiole was deprotonated with butyllithium in THF at -78°C and the resulting phosphonate carbanion reacted with 9-alkyl-acridones to give the dithia-azafulvalenes of type 45 (78BCJ2674) (Scheme 15). 

Tlie starting material for this Wittig-Horner-like olefination was easily accessible by reaction of benzo-l,3-dithiolium-tetrafluoroborate with trimethylphosphite in the presence of an equimolar amount of sodium iodide in dry acetonitrile under nitrogen at room temperature (93% yield). 

Although benzoxazolium salts are more acidic than their benzothiazol analogs in position 2, isolation of the corresponding dioxa-diazafulvalenes was unsuccessful (72LA126). Comparable to the 1,3-dithiolium- and 1,3-thiazolium salts, 1,2,4-dithiazolium salts yielded on treatment with triethylamine in acetonitrile at 0°C mixed geometrical isomers of the TTDAF... 

Azafulvaleiies of type 7-10 constitute electron-poor compounds therefore, only a few reactions using electrophilic agents have been described. Tlius, heating 26a with methyl iodide or benzoyl chloride and subsequent treatment of the resulting products with FIBF4 gave the dithiolium salts... 

Dithiolium salts and dithio- 3-diketone complexes of the transition metals. T. N. Lockyer and R. L. Martin, Prog. Inorg. Chem., 1980, 27, 223-324 (198). 

Wird 4,5-Bis-[methylthio]-2-athylthio-l,3-dithiolium-tetrafluoroborat in Acetonitril/ Tetrabutylammoniumperchlorat (-0,6 V/l F) elektrolysicrt, so entsteht das4,4, 5,5 -Te-trakis-[methylthio]-2,2 -bis- athylthio]-2,2 -bi-l,3-dithiolyl (II) in guten Ausbeuten2 ... 

The reaction of 1,2-dithiolanes with 2- and 4-picolyllithium has been examined <96PS(112)101> and the reactions of thioanhydrides such as 94 with both thiols <95JOC3964> and amines <96TL5337> have been reported. Treatment of 1,2-dithiolium salts with lithium or thallium cyclopentadienide results in formation of a variety of bi-, tri- and tetracyclic products <96LA109>. Reaction of 95 with trimethyl phosphite gives some of the desired coupling product but also the phosphonates 96 <96PS(109)557>. 

Aryl-l,2-dithiolium salts are a source of either dithiatricyclodecadienes (29) or cyclopenta[fc]thiopyrans (30) depending on whether the initial ring opening resulting from reaction with a metal cyclopentadienide is followed by an intramolecular cycloaddition or a condensation <96LA109>. 

Also, the structure of the Ni11 complex (379) with the related ligand dimethyltetrathiomalonate has been determined.997 The geometry at the nickel center is approximately square planar with an inversion center. (379) shows reversible redox properties 998 Oxidation with I2 affords 1,3-bis (methylthio)-1,2-dithiolium triiodide. 

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