Synthesis of Seleno‐Heterocycles via Electrophilic/Radical Cyclization of Alkyne Containing Heteroatoms

Abstract

containing heterocyclic scaffolds by virtue of their interesting reactivities and a broad range of applications in the medicinal and materials chemistry. This review involves the electrophilic/radical cyclization of alkynes containing heteroatoms which resulted into the novel Se‐heterocycles. The synthesis of seleno‐heterocycles via different nucleophiles including O, N, S, Se, Te, and C‐nucleophiles is exhaustively discussed. Also, one‐pot electrophilic cyclization of 1,3‐diynes and 1,3,5‐triynes was described in details. Furthermore, the various mechanisms underlying the synthesis of selenium‐β‐lactam, carbapenem heterocycle, bis‐ and tris‐selenide alkene, β‐selenosulfonation and selenated alkynes were discussed. The Se‐heterocycles reported in this review allow preparing these selenated compounds bearing the selenium moiety both on the rings (outside) and inside the ring (e. g. selenophenes). The review demonstrates the growing opportunities to construct selenium containing heterocycles from alkynes containing heteroatoms.

Aryldiazonium Salts in Photoredox Catalysis – Recent Trends

“…One of the most common reactions of aryl radicals are the addition to alkenes and alkynes substrates [17] . Addition to alkenes usually furnish bifuntionalised molecules such as seleno/thio/aryl/alkyl/keto arenes, [18] whereas addition to alkynes affords functionalized ketones and heterocycles [19] . Similarly, domino addition‐cyclization reactions affords functionalized heterocycles [20] …”

“…[17] Addition to alkenes usually furnish bifuntionalised molecules such as seleno/thio/aryl/alkyl/keto arenes, [18] whereas addition to alkynes affords functionalized ketones and heterocycles. [19] Similarly, domino addition-cyclization reactions affords functionalized heterocycles. [20] In 2012, König's group reported the photocatalytic synthesis of benzothiophenes through a radical addition-annulation process using o-methylthio-diazonium salts and alkynes (Scheme 2).…”

Transition Metal‐Free Synthesis of Carbo‐ and Heterocycles via Reaction of Alkynes with Organylchalcogenides

“…Thus, this manuscript pretends to provide an overview of the most recent progress in the synthesis of carbo‐ and heterocycles prepared through reactions of alkynes with organyl chalcogenides under metal‐free conditions (Scheme 1b). In this sense, organosulfenyl, selanyl and tellanyl halides represent versatile precursors in electrophilic cyclization reactions, commonly used to activate the alkyne and directly install a chalcogenyl group into the cyclic unit [28–30] . Compared to the classical step‐by‐step synthesis of a target cycle followed by chalcogen incorporation, the direct cyclization‐functionalization leads to the formation of several bonds in one pot.…”

Microwave-Assisted Synthesis of Quinazolines and Quinazolinones: An Overview

“…Although the aforementioned reactions are considered as the most important transition-metal catalyses, a plethora of vital reactions can be effectively catalyzed by various transition metals including reductive elimination, oxidative addition, and transmetallation. Transition metal catalysis has also found extensive applications in the convenient and efficient synthesis of a wide variety of heterocyclic systems (Ma et al, 2017 ; Ramanathan and Liu, 2017 ; Tiwari and Bhanage, 2017 ; Chatterjee et al, 2018 ; Saikia et al, 2018 ; Chen et al, 2020 ; Debabrata et al, 2020 ; Ghosh et al, 2020 ; Janardhanan et al, 2020 ; Jiang et al, 2020 ; Kanwal et al, 2020 ; Kojima and Matsunaga, 2020 ; Li and Zhang, 2020 ; Nagata and Obora, 2020 ; Neto and Zeni, 2020a , b ; Pal et al, 2020 ; Ratmanova et al, 2020 ; Sahiba and Agarwal, 2020 ; Sonawane et al, 2020 ; Xuan et al, 2020 ). However, the literature survey revealed only an example of zinc (Shi et al, 2004 ), a limited number of iron-catalyzed (Melvin et al, 1992 ; Valderrama et al, 1999 ; Kanth et al, 2006 ; Yin et al, 2012 ; Gopalaiah et al, 2017 , 2019 ; Raut and Bhanage, 2017 ; Eidi et al, 2018 ), and relatively more copper-catalyzed reactions, leading to the synthesis of quinazoline and quinazolinone derivatives (Melvin et al, 1992 ; Chatterjee et al, 2018 ; Potuganti et al, 2018 ; Liang et al, 2019 ; Rodrigues et al, 2019 ; Donthiboina et al, 2020 ).…”