New methodology of nucleophilic substitution at three different centers of a seleniranium intermediate in reactions of 2-bromomethyl-1,3-thiaselenole with mercapto benzazoles

Abstract

Regio- and stereoselective reactions accompanied by rearrangements with ring extension or contraction.

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

“…The formation of the six-membered heterocycle of 2,3-dihydro-1,4-thiaselenin-2-yl selenocyanate 5 was confirmed, inter alia, by the observation of two doublets corresponding to the olefinic protons of the SCH=CHSe group with 3 J = 9.9 Hz in the 1 H NMR spectrum (Table 1, entry 2). In the case of five-membered compounds 1 and 4, the coupling constant of the olefinic protons of the SCH=CHSe group would be 3 J H,H = 6.3 Hz [32,40]. The SCHSe group of the heterocycle 5 was characterized by a doublet of doublets at 5.21 ppm ( 3 J = 2.1 and 3 J = 6.6 Hz).…”

“…A fundamental approach to the regio-and stereoselective synthesis of unsaturated functionalized organoselenium compounds was developed during the last ten years based on new directions for nucleophilic substitution reactions proceeding via intermediate seleniranium cations 2 generated from thiaselenole 1. We have carried out new regioselective reactions of thiaselenole 1 with dithiocarbamates [31], ketones [37], thiols [38,39], dithiols [38], and mercapto benzazoles [40]. These are the first examples of a nucleophilic attack at the selenium atom of the seleniranium cation 2 with the generation of a new Se-S bond, yielding new families of linear unsaturated (Z)-2-[(organylsulfanyl)selanyl]ethenyl vinyl sulfides (Scheme 3).…”

“…Cascade regio-and stereoselective reactions of thiaselenole 1 with water and ethylene glycol resulted in the formation of the first representatives of the new family of polyfunctional 2,3dihydro-1,4-thiaselenines [41]. The regioselective nucleophilic substitution reactions in thiaselenole 1 proceeding at the C2 carbon atom of the seleniranium cation 2 with dithiocarbomates [31], thiourea [32], alcohols [42], functionalized organic acids [43,44], functionalized pyridines [45], ammonium thiocyanate [46], and mercapto benzazoles [40] were developed (Scheme 4).…”

“…The article was included in the RSC themed web collection "The chemistry of Selenium & Tellurium at the beginning of the 3rd millennium" [40].…”

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

“…The selenium-containing heterocyclic drug ebselen is applied for the prevention and treatment of human ischemic stroke [21]. The development of effective approaches to novel selenium heterocycles by regioselective cyclization and annulation reactions is one of the main directions of our research [22][23][24][25][26][27][28][29][30][31]. The reactions of 2-pyridinesulfenyl and 2-pyridineselenenyl chlorides with some alkenes have been described [32][33][34][35][36][37][38][39][40][41].…”