Dichalcogenides/Oxone^®‐Mediated Cyclization of (Z)‐Chalcogenoenynes under Ultrasound Irradiation

Abstract

3‐Selanyl‐ and 3‐tellanylchalcogenophenes were prepared by the electrophilic cyclization of (Z)‐chalcogenoenynes under ultrasound irradiation conditions. This green procedure was carried out using Oxone® as an inexpensive and non‐toxic oxidant agent to promote the oxidative cleavage of Se−Se and Te−Te bonds. The electrophilic cyclization of (Z)‐1‐propylthio‐ and (Z)‐1‐butylselen‐1‐en‐3‐ynes was performed using the diaryl diselenide or ditelluride/Oxone®/ethanol system. The respective 3‐arylselanyl and 3‐aryltellanylthiophenes and selenophenes were obtained in 40 % to 87 % yield (16 examples). Similarly, 3‐arylselanyl and 3‐aryltellanyltellurophenes were synthesized by the cyclization of (Z)‐1‐butyltelluro‐1‐en‐3‐ynes, using glycerol as the solvent instead ethanol (5 examples; 28 % to 65 % yield). For the first time, Oxone® was used in the selective oxidative cleavage of the Te−Te bond in cyclization reactions.

Synthesis of 3,4-Bis(Butylselanyl)Selenophenes and 4-Alkoxyselenophenes Promoted by Oxone®

“…Thus, based on our own results and in the literature on the reactivity of Oxone ® [ 57 , 58 , 59 , 60 , 61 ] and electrophilic cyclization reactions [ 53 , 54 , 55 ], a plausible mechanism for the formation of 3,4-bis(butylselanyl)selenophene 3c and 3-(butylselanyl)-4-ethoxy-2,5-di-4-tolylselenophene 4h , through the reaction of 1,4-bis-4-tolylbuta-1,3-diyne 1c with dibutyl diselenide 2a promoted by Oxone ® , is presented in Scheme 3 . The first step for the synthesis of 3c and 4h consisted of the formation of the electrophilic selenium species, A and B , via ionic or radical pathways, from the reaction between dibutyl diselenide 2a and potassium peroxymonosulfate (KHSO 5 ), the active component of Oxone ® [ 57 , 58 , 59 ].…”

“…Considering the growing potential utility of selenophenes in pharmaceutical, materials science, and organic synthesis, different methodologies have been reported for the preparation of this class of compounds [ 51 ]. Among these protocols, a general approach for the synthesis of 3-substituted selenophenes is the electrophilic cyclization of ( Z )-selenoenynes with different electrophiles, such as I 2 , ICl, PhSeBr, and PhSeCl ( Scheme 1 a, path i) [ 52 ] or with electrophilic selenium species generated in situ from diorganyl dichalcogenides in the presence of FeCl 3 [ 5 ] or Oxone ® [ 53 ] ( Scheme 1 a, path ii). In addition, in 2017 the electrophilic cyclization of selenoenynes in the presence of an appropriate nucleophile, affording 3-iodo-selenophenes and 3-organoselanyl-selenophenes ( Scheme 1 b), was reported [ 54 ].…”

Ultrasound irradiation in heterocycle synthesis: An overview

“…The ultrasound‐assisted protocol for the cyclization of Z ‐chalcogenoenynes was disclosed by Soares et al [19]. The reaction of butyl(1,4‐diphenylbut‐1‐en‐3‐yn‐1‐yl)selane and diphenyl diselenide using oxone as an oxidant in ethanol under ultrasound irradiation for 60 min resulted in the product in 78% (Scheme 3), while the same reaction by refluxing for 24 h resulted in 77% yield.…”

Recent Advances in the Oxone-Mediated Synthesis of Heterocyclic Compounds

“…In 2020, some of us reported an Oxone/dichalcogenide-promoted synthesis of 3selanyl-chalcogenophenes and 3-tellanylchalcogenophenes 60-62, through the electrophilic cyclization of (Z)-chalcogenoenynes 63-65, under ultrasound irradiation (Scheme 42) [47]. The annulation of (Z)-1-butylselen-1-en-3-ynes 63 was conducted in the presence of several diorganyl diselenides 21 and diphenyl ditelluride 41a, affording the respective 3arylselanyl-and 3-aryltellanylselenophenes 60 in poor to very good yields.…”