Synthesis of condensed sulfur- and nitrogen-containing heterocycles via polar cycloaddition of hetarene sulfenyl chlorides to a C–C multiple bond

Османов

et al. 2012

One of the current and efficient routes to the synthesis of heterocyclic compounds is the so called selenocyclofunctionalization which is based on the reaction of organoselanyl chlorides with unsaturated compounds and it occurs with closing of the ring at an atom of the functional group contained in the unsaturated substrate molecule [1-10]. Various classes of heterocycles have been synthesized by this route.We have recently discovered that reaction of styrene with pyridine-2-selanyl chloride (1) in methylene chloride gives the heterocycle product with ring closure at the pyridine nitrogen atom of the starting reagent, namely the 3-phenyl-2,3-dihydro[1,3]selenazolo[3,2-a]pyridinium-4-chloride [11]. It was also found that the primary product of this reaction is the 2-chloro-1-phenyl-2-(2-pyridylselanyl)ethane which then undergoes intramolecular cyclization.With the aim of revealing the synthetic possibilities of this heterocyclization and determining its regioand stereochemistry, we have studied the reactions of the selanyl chloride 1 with the variously structured alkenes and dienes: 3,3-dimethyl-1-butene (2), trans-stilbene (3), (1E,3E)-1,4-diphenyl-1,3-butadiene (4), cyclopentene (5), cyclopentadiene (6), indene (7), norbornene (8), and norbornadiene (9).It was found that reactions of the selanyl chloride 1 with the unsaturated compounds 2-7 in methylene chloride at 20ºC, as well as the reaction with styrene, result in formation of the condensed selenium-and nitrogen-containing systems 10-15 with high yields.By contrast to the above, the reaction of the selanyl chloride 1 with the unsaturated hydrocarbons of the bicyclo[2.2.1]heptane series, namely the compounds 8 and 9, occurs under the same conditions to form only the products of 1,2-addition of the selanylating reagent at the multiple bonds, namely β-chloroalkyl selenides 16 and 17, respectively in quantitative yields.

mentioning

confidence: 85%

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confidence: 99%

See 1 more Smart Citation

Synthesis of 2,3-dihydroselenazolo[3,2-a]pyridinium salts based on reactions of pyridine-2-selanyl chloride with alkenes and dienes

Османов

et al. 2012

“…In this connection, we have now synthesized 2-chloroselanyl-1-pyridine 1-oxide (1) and studied its reaction with styrene (2a) and trans-stilbene (2b). We have found that the reaction of the selanyl chloride 1 with the alkenes 2a,b in nitromethane in the presence of an equimolar amount of lithium perchlorate occurs by a polar cycloaddtion [5] to give the 2,3-dihydropyrido[1,2-b][1,4,2]oxaselenazin-5-ium derivatives 3a,b in 76 and 82% yield respectively. ClO 4 -+ + 1 H NMR spectroscopy was used to show that the reaction studied is regio-and stereospecific.…”

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confidence: 99%

Synthesis of novel heterocyclic systems. 2,3-dihydropyrido[1,2-b][1,4,2]oxaselenazin-5-ium

Османов

2010

We have recently proposed a method for the synthesis of the novel 2,3-dihydropyrido[1,2-b][1,4,2]-oxathiazinium-5 heterocyclic system based on the heterocyclization of 2-chlorosulfenyl-1-pyridine 1-oxide with unsaturated compounds [1][2][3][4]. As far as we known, analogous selenium containing heterocycles have not been prepared to this time. In this connection, we have now synthesized 2-chloroselanyl-1-pyridine 1-oxide (1) and studied its reaction with styrene (2a) and trans-stilbene (2b). We have found that the reaction of the selanyl chloride 1 with the alkenes 2a,b in nitromethane in the presence of an equimolar amount of lithium perchlorate occurs by a polar cycloaddtion [5] to give the 2,3-dihydropyrido[1,2-b][1,4,2]oxaselenazin-5-ium derivatives 3a,b in 76 and 82% yield respectively. Se O N Ph R N SeCl O R Ph MeNO 2 LiClO 4 1 2a,b 3a,b + 2, 3 a R = H, b R = PhClO 4 -+ + 1 H NMR spectroscopy was used to show that the reaction studied is regio-and stereospecific. IR spectra were recorded on a Shimadzu IR-Prestige-21 spectrometer for KBr tablets. 1 H NMR spectra were taken on a Bruker AM-300 instrument (300 MHz) using DMSO-d 6 and with TMS as internal standard.2-Chloroselanyl-1-pyridine 1-Oxide (1). A solution of sulfuryl chloride (0.27 g, 2 mmol) in dichloromethane (15 ml) was added to a solution of 2-selanyl-1-pyridine 1-oxide (0.35 g, 2 mmol) (prepared by method [6]) in dichloromethane (20 ml) at 20ºC. After 1 h it was filtered to give compound 1 (0.33 g, 80%) and the filtrate was evaporated in vacuo. Recrystallization of the residue from dichloromethane gave a further 0.06 g (15%) of compound 1; mp 160-162ºC.

“…We have already shown that reactions of alkenes with hetarenesulfenyl and hetareneselanyl chlorides containing potentially nucleophilic nitrogen atoms in the hetaryl fragment proceeds as tandem addition-cyclization reactions to give S,N-and Se,N-heterocycles [1][2][3][4][5][6].…”

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confidence: 99%

Synthesis and reactions of 2-pyridinetellurenyl chloride

2009

We have already shown that reactions of alkenes with hetarenesulfenyl and hetareneselanyl chlorides containing potentially nucleophilic nitrogen atoms in the hetaryl fragment proceeds as tandem addition-cyclization reactions to give S, .In the present work, in a study of the use of such cyclization reactions in the synthesis of tellurium heterocycles, we obtained 2-pyridinetellurenyl chloride (1) and studied its reactions with 3,4-dihydro-2H-pyran (2) and indene 3. The reaction of telllurenyl chloride 1 with unsaturated compounds 2 and 3 in methylene chloride at 20°C gave condensed systems 4 (in 84% yield) and 5 (in 95% yield). N TeCl Te O N H H O Te N H H 2 3 4 5Cl -+ + Cl -1 1 H NMR spectroscopy was used to show that these reactions are both regiospecific and stereospecific. In light of the data on the stereochemistry of addition to 3,4-dihydro-2H-pyran and indene [7-10] and our previous results [1-6], we may assume that there is cis-fusion of the tellurazole ring with the tetrahydropyran and indane units, respectively.The 1 H NMR spectra were taken on a Bruker AM-300 spectrometer at 300 MHz in DMSO-d 6 with TMS as the internal standard. The IR spectra were taken on a Shimadzu IR-Prestige-21 spectrometer.2-Pyridinetellurenyl Chloride (1). A solution of sulfuryl chloride (0.14 g, 1 mmol) in methylene chloride (10 ml) was added to a solution of di(2-pyridyl) ditelluride (0.41 g, 1 mmol) obtained according to the procedure of Engman and Cava [11]. After 1 h, 0.26 g (54%) chloride 1 was filtered off. The filtrate was