1,3,2-Dithiazolidine cations

C and 14N NMR spectra of 1,3,2-dithiazolidine cations 2, 28, and 29 are in full agreement with their H NMR spectra (see Figure 2) and are likely to be diagnostic for derivatives of this family of heterocycles <1996JCD1997>. 

The dithionitronium cation SNS+ (as the AsFg salt) underwent quantitative concerted symmetry-allowed cycloaddition reactions with alkenes (ethylene, methylethylene, trans- and +r-l,2-dimethylethylene, 1,1-dimethyl-ethylene, tetramethylethylene, and norbornene) to give 1,3,2-dithiazolidine cations 76 (Equation 20) <1996JCD1997>. 

In the reaction of SNS+ AsF with olefins, concerted symmetry-allowed cycloadditions occur with formation of the 1,3,2-dithiazolidine cations 102 . The reactions are conducted in liquid sulfur dioxide at 60-70 °C using a molar ratio of 1 1. 

The main structural types of the azoles are given in Figure 1. Most of them are experimentally available and stable at room temperature. The basic parent structures are shown in row A and named as 1,3,2-dithiazoles, 1,3,2-dithiazolidines, 1,3,2-dioxazoles, and 1,3,2-dioxazolidines. Row B represents the known 1,3,2-dithiazolium and dithiazolidinium cations and 1,3,2-dithiazolyl and 1,3,2-dithiazolidinyl radicals, respectively. 

The structures of compounds containing a 1,3,2-dithiazole ring (1,3,2-dithiazolidines, 1,3,2-dithiazoles, 1,3,2-dithia-zolium cations and radicals) were extensively investigated by X-ray and electron diffraction between 1980 and 1990 <1996CHEC-II(4)433>. Nuclear magnetic resonance (NMR) spectroscopy was found to be very effective for elucidation of the structure of 1,3,2-dioxazoles and 1,3,2-dithiazoles. Electron spin resonance (ESR) spectra of the 1,3,2-dithiazolyl radicals gave important information on their structures. 

The perfluorodisulfonamide 56 has been sulfinated with CF3SC1 or (F2CSC1)2 to form compound 57 or 58 <1995CB429>, both of which are stable at ambient temperatures and decompose near 100°C. Oxidation of N-sulfinated derivative 57 with AsFs yields salt 59 and by-products, which suggests formation of the corresponding cation radical as an intermediate in this reaction. Pure salt 59 is more cleanly accessible by the reaction of 1,3,2-dithiazolidine 56 with AsFs (Scheme 4). 

The synthesis of 1,3,2-dithiazolidines from bis(sulfenylchlorides) and amines has been developed in the 1990s and 2000s (Equations 12 and 14). Trimethylsilyl azide confirmed its important role in the preparation of fused mono- and bis-l,3,2-dithiazolium cations (Equation 18). Oakley and co-workers showed that o-dimercapto derivatives can be used in the synthesis of these compounds if treated with trithiazyl trichloride (Equation 19). Synthesis of iV-substituted 1,3,2-benzodithazole tetraoxide has been successfully carried out from benzene-bis(sulfonylchloride) and aliphatic amines (Equation 15). An important feature in this reaction is the preparation of chiral derivatives from optically pure amines (Equations 16 and 17). 

The most important ability of 1,3,2-dithiazoles is to form stable cations and radicals therefore, they have been considered as promising conducting charge-transfer complexes and ferromagnetic materials <1996CHEC-II(4)433>. 1,3,2-Dithiazolidines have been claimed to have use in photographic materials. 

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