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Electrophilic reactions of sulfur dichloride with unsaturated systems underlie one of the most general methods for the synthesis of bis(2-chloroalkyl) sulfides [1]. Reactions of analogous unsaturated compounds with selenium tetrachloride yield the corresponding bis-adducts containing a four-coordinate selenium atom (>SeCl2) [2]. In recent years we performed systematic studies on reactions of SeCl2 with alkenes and their oxygenand sulfur-containing derivatives [3, 4]. Reactions with chlorinated ethylenes, such as chloroethene, 1,1and 1,2-dichloroethenes, and trichloroethene were reported only for SCl2, and they required the presence of Lewis acids as catalyst [5]. Garratt et al. [6] showed that SeCl4 failed to react with 1,2-dichloroethene in the presence of AlCl3 as catalyst. Nevertheless, we succeeded in adding SeCl2 to bis(2-chlorovinyl) selenide (a selenium-containing derivative of 1,2-dichloroethene) in the absence of a catalyst [7]. Sulfur and selenium dichlorides are known to act as chlorinating agents toward alkylsulfanyl derivatives of polychloroethenes, e.g., alkyl 2,2-dichlorovinyl sulfides [8].

The electrophilic additiob of sulfur dichloride and selenium tetrachloride to diallyldimethylsilane proceeds strictly according Markownikoff rule and results in the formation of previously unknown saturated siliconcontaining heterocycles, 5,5-dimethyl-3,7-dichloro-1,5-thiasilacyclooctane and 5,5-dimethyl-1,1,3,7-tetrachloro-1,5-selena(IV)silacyclooctane. The structure of heterocycles obtained was confi rmed by 1H, 13C NMR spectra, in the case of selenium-containing heterocycle, by 77Se NMR spectrum, among them the 2D HMBC spectrum.

Divinyl sulfide is a multipurpose product in modern organic synthesis [1]; various heterocyclic compounds were obtained on its basis [2]. Earlier, we have studied the reactions of divinyl sulfide with selenium dichloride and dibromide, which, when carried out at room temperature in chloroform, result in 5-halo-2halomethyl-1,3-thiaselenolanes, whereas in CCl4, in 2,6-dihalo-1,4-thiaselenanes [3–6].

Selenium dichloride and dibromide were not isolated as individual substances. It is known that selenium dichloride in solution exists in equilibrium with selenium tetrachloride and Se2Cl2, whereas the equilibrium of selenium dibromide in solution involves Se2Br2 and bromine [1, 2]. We were the first to reveal that freshly prepared selenium dichloride and selenium dibromide can be used in selective synthesis of organic selenides [3, 4]. Reactions of selenium dichloride and dibromide with divinyl chalcogenides and their derivatives opened a synthetic route to new heterocyclic compounds [5–10]. In continuation of our systematic studies on the chemical properties of selenium dihalides [3–10], we examined previously unknown addition of selenium dichloride to divinyl sulfone. It was found that the reaction occurs with high regioselectivity and leads to the formation of a new four-membered heterocyclic compound, 2,4-bis(chloromethyl)-1,3-thiaselenetane 1,1-dioxide (I). The yield of compound I was 85%, calculated on the reacted divinyl sulfone, the conversion of the latter being 58%. sional correlation techniques, as well as by mass spectrometry and elemental analysis. According to the NMR data, compound I was isolated as a mixture of two diastereoisomers at a ratio of 2.5 : 1. 2,4-Bis(chloromethyl)-1,3-thiaselenetane 1,1-dioxide (I). mp 76–77°C. Major diastereoisomer: H NMR spectrum, δ, ppm: 3.91 d.d (2H, CH2Cl, J = 11.8, J = 7.1 Hz), 4.27 d.d (2H, CH2Cl, J = 11.8, J = 7.1 Hz), 5.52 d.d (2H, CHSe, J = 7.1, 7.1 Hz). C NMR spectrum, δC, ppm: 41.39 (CH2Cl), 69.36 (CHSe). Se NMR spectrum: δSe 193 ppm. Minor diastereoisomer: H NMR spectrum, δ, ppm: 3.93 d.d (2H, CH2Cl, J = 11.9, J = 7.7 Hz), 4.31 d.d (2H, CH2Cl, J = 11.9, J = 7.9 Hz), 5.54 d.d (2H, CHSe, J = 7.7, 7.9 Hz). C NMR spectrum, δC, ppm: 41.63 (CH2Cl) , 70.03 (CHSe) . Se NMR spectrum: δSe 200 ppm. Mass spectrum, m/z (Irel, %): 268 (29) [M], 204 (12), 169 (100), 142 (56), 133 (34), 107 (82), 93 (24), 81 (13), 61 (19), 53 (21). Found, %: C 17.69; H 2.21; Cl 26.30. C4H6O2Cl2SSe. Calculated, %: C 17.93; H 2.26; Cl 26.46. The NMR spectra were recorded from solutions in CDCl3 on a Bruker DPX-400 instrument at 400.13 (H, HMDS), 100.61 (C, HMDS), and 76.30 MHz (Se, Me2Se). The mass spectrum (electron impact, 70 eV) was obtained on a Shimadzu GCMS-QP5050A instrument. This study was performed in the framework of the Basic Research Program of the Russian Academy of Sciences (project no. 5.1.8).

Selenium dichloride is a promising reagent for organic synthesis. However, prior to our studies [1, 2], it was not used for the preparation of organoselenium compounds. It is known that selenium dichloride in solution exists in equilibrium with selenium tetrachloride and Se2Cl2 [3]. No examples of aromatic electrophilic substitution with participation of selenium dihalides have been reported so far. While continuing our systematic studies on reactions of selenium dihalides [1, 2, 4–10], we examined the reaction of selenium dichloride with methoxybenzene. The reaction occurred as aromatic replacement of hydrogen by the electrophile Se and afforded bis(4-methoxyphenyl) selenide (I) in high yield (91%). Thus selenium dichloride may be used as source of electrophilic Se species in aromatic electrophilic substitution reactions. The possibility of using selenium dihalides for performing analogous reactions with other aromatic systems is now under study. Bis(4-methoxyphenyl) selenide (I). mp 54–55°C; published data [11]: mp 54°C. H NMR spectrum, δ, ppm: 7.28 d (4H, CH, J = 7.4 Hz), 6.69 d (4H, CH, J = 7.4 Hz), 3.72 s (6H, CH3O). C NMR spectrum, δC, ppm: 158.85 (C), 135.24 (C), 122.04 (C), 114.53 (C), 54.49 (CH3O). Mass spectrum, m/z (Irel, %): 294 [M] (75), 214 (100), 199 (96), 187 (14), 171 (28), 144 (12), 128 (25), 107 (77), 92 (13), 77 (14), 63 (47), 39 (18). The H and C NMR spectra were recorded on a Bruker DPX-400 spectrometer at 400.13 and 100.61 MHz, respectively, from a solution in carbon tetrachloride; the chemical shifts were determined relative to hexamethyldisiloxane. The mass spectrum (electron impact, 70 eV) was obtained on a Shimadzu GCMS-QP5050A instrument.