Seleniranium and Telluriranium Salts

Abstract

Seleniranium salts [Ad SeR] X (2-8), which are moderately stable at room temperature, were synthesized by addition of RSe X equivalents to the bulky olefin bis(adamantylidene) Ad=Ad (1), where R is aryl or alkyl and X is Tf N , B(C F ) , or SbCl . Unstable telluriranium salts [Ad TeR] X (9-12) were obtained by addition of RTe X equivalents to 1 (R=Ph, Et; X =Tf N , BF ). The compounds were characterized by NMR spectroscopy and quantum chemical calculations, and the Se compounds also by ESI mass spectrometry. Crystal structures were determined for seleniranium salts 2 and 7 and telluriranium salt 9.

Natural Compounds and Their Structural Analogs in Regio- and Stereoselective Synthesis of New Families of Water-Soluble 2H,3H-[1,3]thia- and -Selenazolo[3,2-a]pyridin-4-ium Heterocycles by Annulation Reactions

“…It is known that electrophilic addition of sulfenyl halides to linear 1-alkenes afforded predominantly anti-Markovnikov products [44][45][46][47]. Thiiranium [45][46][47][48] and seleniranium [47][48][49][50][51][52][53][54] cations are often regarded as intermediates in electrophilic addition of chalcogenyl halides to the double bond, and attack of the halide anion occurs at unsubstituted carbon atom of thiiranium or seleniranium cations leading to Suggested reactions pathways can be regarded on the examples of reactions of 2-pyridinechalcogenyl halides with styrene and allylbenzene (Scheme 6). The reactions of 2-pyridinesulfenyl and selenenyl halides with compounds containing a double bond conjugated with the benzene ring (isoeugenol, methyl isoeugenol, trans-anethole, styrene, 4-methylstyrene, α-methylstyrene) proceed regioselectively via electrophilic addition of the chalcogen atom at β-carbon atom of the double bond.…”

“…It is known that electrophilic addition of sulfenyl halides to linear 1-alkenes afforded predominantly anti-Markovnikov products [44][45][46][47]. Thiiranium [45][46][47][48] and seleniranium [47][48][49][50][51][52][53][54] cations are often regarded as intermediates in electrophilic addition of chalcogenyl halides to the double bond, and attack of the halide anion occurs at unsubstituted carbon atom of thiiranium or seleniranium cations leading to In the case of eugenol, its derivatives and structural analogs, 2-pyridinesulfenyl and selenenyl halides react with allyl group as with linear 1-alkene and electrophilic addition of the chalcogen atom occurs at α-carbon atom of the double bond (C and D are possible intermediates in the reaction of 2-pyridinesulfenyl chloride with allylbenzene) followed by intramolecular nucleophilic substitution in the formed anti-Markovnikov adduct (Scheme 6). It is known that electrophilic addition of sulfenyl halides to linear 1-alkenes afforded predominantly anti-Markovnikov products [44][45][46][47].…”

“…Thiiranium [45][46][47][48] and seleniranium [47][48][49][50][51][52][53][54] cations are often regarded as intermediates in electrophilic addition of chalcogenyl halides to the double bond, and attack of the halide anion occurs at unsubstituted carbon atom of thiiranium or seleniranium cations leading to anti-Markovnikov products. Besides, the formation of thiiranium and seleniranium species determines the reaction course as anti-addition in reactions of sulfenyl and selenenyl halides with alkenes.…”

Remarkable Alkene-to-Alkene and Alkene-to-Alkyne Transfer Reactions of Selenium Dibromide and PhSeBr. Stereoselective Addition of Selenium Dihalides to Cycloalkenes

“…Some of them have been detected or isolated [57][58][59][71][72][73][74]. Recently, Poleschner and Seppelt isolated and fully characterized series of moderately stable seleniranium and telluriranium salts [73]. The seleniranium ions have been found to play a key role in the process of chirality transfer in asymmetric synthesis reactions studied by Wirth, Santi, Back, and others [60][61][62][63][64][65][66][67].…”

“…Wirth and co-workers have postulated facile alkene-to-alkene transfer of selenenium cations in the asymmetric reactions [60,63]. In the reports of Seleniranium species have been discussed for a long time as reactive intermediates in addition reactions of selenium-centered electrophiles to the double bond [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74]. Some of them have been detected or isolated [57][58][59][71][72][73][74].…”