E. O. Kurkutov

Synthesis of a new four-membered heterocycle by reaction of selenium dichloride with divinyl sulfone

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).

Stereoselective synthesis of 5-bromo-2-bromomethyl-1,3-thiaselenolane 1,1-dioxide by addition of selenium dibromide to divinyl sulfone

Earlier we have studied the reactions of selenium dichloride and dibromide with divinyl sulfide and have shown that the course of the reactions is strongly solvent-dependent [4–8]. Reactions of selenium dihalides with divinyl sulfide in CCl4 at room temperature result in the six-membered heterocycles, 2,6-dihalo-1,4-thiaselenanes [4–6]. The same reagents in chloroform at room temperature react with the formation of the five-membered heterocycles, 5-halo2-halomethyl-1,3-thiaselenolanes [5–8]. The reaction of selenium dibromide with divinyl sulfone in chloroform proceeds with high selectivity at room temperature and gives rise exclusively to the fourmembered heterocycle, 2,4-bis(bromomethyl)-1,3thiaselenetane 1,1-dioxide II in quantitative yield with respect to the reacted divinyl sulfone whose conversion was 24% [9]. Product II is a mixture of two diastereomers in the ratio of 7 : 1.

Reaction of selenium dihalides with allyl benzyl ether

In recent time the chemistry of selenium dihalides has been extensively developed. Selenium dihalides have been shown to be efficient and selective reagents in the synthesis of organoselenium compounds. Although neither selenium dichloride nor selenium dibromide can be isolated in the pure state [1], these reagents can be generated in situ and involved in various transformations [2–14]. We perform systematic studies on reactions of selenium dichloride and dibromide with unsaturated compounds [5–14]. The reaction of selenium dihalides with vinyl ethers gave the corresponding Markovnikov adducts, bis(2-halo-2-organyloxyethyl) selenides, in high yield [8, 9]. The double C=C bond in vinyl chalcogenides is conjugated with the lone electron pair on the chalcogen atom, which largely determines chemical behavior of that bond. No such conjugation exists in the molecules of allyl chalcogenides. The reactions of selenium dichloride and dibromide with diallyl ether, diallyl sulfide, and diallyl selenide led to the formation of sixmembered heterocycles, 3,5-bis(halomethyl)-1,4-chalcogenaselenanes, whose structure corresponds to the anti-Markovnikov addition [10–12]. The reactions of selenium dihalides with divinyl and diallyl tellurides involved halogenation of the tellurium atom [13, 14]. In continuation of our studies on reactions of selenium dihalides with unsaturated chalcogenides [5–14], the present communication reports on the reaction of selenium dichloride and dibromide with allyl benzyl ether (I). The reactions were carried out in carbon tetrachloride or chloroform at room temperature, and the products were the corresponding antiMarkovnikov adducts, bis(3-benzyloxy-1-halopropan2-yl) selenides II and III, which underwent gradual rearrangement into thermodynamically more stable Markovnikov adducts IV and V. Conditions ensuring selective formation of compounds IV and V in high yield were found.

Rearrangements in methanolysis of bis(2-bromoalkyl)selenides

Addition of selenium dibromide to 1-hexene, 1-octene, and allylic ethers occurs through the formation of intermediate kinetic anti-Markovnikov adducts that further transform into more thermodynamically stable Markovnikov adducts presumably via seleniranium intermediates. The methanolysis of both Markovnikov and anti-Markovnikov adducts leads to the formation of the same products in approximately the same ratio thus showing that the reaction proceeds through seleniranium intermediates.

Regioselective reaction of selenium dihalides with methyl vinyl ketone

We perform systematic studies on reactions of selenium dichloride and dibromide with unsaturated compounds [2–5]. Selenium dihalides were found to react with divinyl sulfide and divinyl selenide with formation of the corresponding Markovnikov adducts, 2,6-dihalo-1,4-thiaselenanes and -diselenanes, whose subsequent rearrangement yields thermodynamically more stable 1,3-thiaselenolanes and -diselenolanes [2]. Unlike vinyl sulfides, the double C=C bond in vinyl sulfones is deactivated toward electrophilic addition due to strong electron-withdrawing effect of the sulfonyl group. Reactions of selenium dihalides with divinyl sulfone are slower than with divinyl sulfide, and selenium adds to both βand α-position of the double bond with formation of fourand five-membered heterocycles [3].

Bis(1,3-dioxolan-2-ylmethyl)selenide

The reaction of selenium dihalides with 2-vinyloxyethanol has been performed for the first time, and the method of preparation of bis(1,3-dioxolan-2-ylmethyl)selenide in quantitative yield has been proposed.

Effective synthesis of bis(1,4-dioxan-2-ylmethyl)selenide and selenoxide

Selenium-containing heterocyclic compounds possess versatile biologic activity. For instance, 2-phenyl-1,2-benzoselenazol-3(2H)-one (ebselen) exhibits a high glutathione peroxidase-like action, 1-methyl-1,3dihydro-2H-imidazole-2-selenone possesses an antithyroid action, and a number of other selenium-containing heterocylic compounds show a high antibacterial and antimicotic activity [1]. As effective reagents for the synthesis of organoselenium compounds selenium dihalides are known whose chemistry is intensively developing lately [2–7]. The heterocylization at the use of selenium dihalides may occur as an addition to diene compounds [2, 3], as annulation (combination of addition with electrophilic aromatic substitution) [4, 5], or as a result of addition to unsaturated compounds containing nucleophilic groups accompanied with intramolecular nucleophilic substitution [6, 7].

Synthesis of Fused Compounds on the Basis of Chalcogen Chlorides and 2-Allylphenols

Efficient methods have been developed for regioselective synthesis of new organochalcogen compounds containing 2,3-dihydro-1-benzofuran-2-ylmethyl and 7-methyl-2,3-dihydro-1-benzofuran-2-ylmethyl substituents by reactions of selenium and sulfur dichlorides and tellurium tetrachloride with 2-allylphenol and 2-allyl-6-methylphenol.

Synthesis of New 1,1′-Selanediyldi(alkan-2-ols)

A procedure has been developed for the synthesis of 1,1′-selanediyldi(alkan-2-ols) by reaction of selenium dibromide with terminal alkenes and subsequent hydrolysis of the addition products in DMF at room temperature in the absence of a base.

Synthesis of bis(2-haloalkyl) selanes and selenides based on selenium dioxide and terminal alkenes

Selenium tetrahalides generated from selenium dioxide and hydrogen halides (HCl, HBr) reacted with hex-1-ene, hept-1-ene, and oct-1-ene at a SeO2‒alkene molar ratio of 1: 2 to give mixtures of dihalobis-(2-haloalkyl)-λ4-selanes (yield 80‒90%) and bis(2-haloalkyl) selenides (yield 5‒12%). Halogenation of the resulting mixtures afforded 85‒93% (calculated on the initial SeO2) of the corresponding dihalobis(2-haloalkyl)-λ4-selanes, and the reduction of the same mixtures with Na2S2O5 gave bis(2-haloalkyl) selenides in 80‒86% yield. In the reaction with a SeO2‒alkene ratio of 5: 8, pure dihalobis(2-haloalkyl)-λ4-selanes were formed in 84‒93% yield. Dichlorobis(2-chloro-2-phenylethyl)-λ4-selane was obtained in 72% yield in the reaction of SeO2‒HCl with styrene.