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

Abstract

This manuscript intends to overview the most recent advances in the synthesis of carbo‐ and heterocycles through reactions of alkynes with organyl chalcogenides (S, Se, Te) under metal‐free conditions. Firstly, the use of electrophilic chalcogenyl halides as a selective reagent for alkyne carbon‐carbon triple bond activation will be presented. After that, radical cyclization protocols employing electrochemical oxidative conditions, light‐induced photoredox catalysis, or mild oxidants with direct chalcogenyl group installation will be discussed accompanied by the proposed mechanisms.

Solvent‐Regulated Electrochemical Selenylation and Deuteration of Alkynyl Aryl Ketones: Chemoselective Synthesis of 3‐Selenylated Chromones and Deutero‐Selenylated Chalcones

“…Therefore, in recent years, extensive research efforts have been devoted to the development of synthetic methods of chromones (Scheme 1a). [3] Moreover, the incorporation of an organoselenium group in the structure of chromones has also attracted great attention due to their potential applications in synthetic chemistry [4] as well as their broad biological properties. [5] However, these methods usually suffer from obvious drawbacks, such as using excessive transition metals or strong oxidants, [6] making them environmentally unfriendly and leading to poor functional group compatibility.…”

Recent Approaches in Transition Metal-Catalyzed Chalcogenative Heteroannulation of Alkenes and Alkynes

“…In sum, the interesting properties presented by organochalcogen compounds offer wide research opportunities, considering the design of small molecules presenting pharmacological activity and toxicological safety to new materials. The heterocyclization of alkenes and alkynes by using halogen- [30][31][32][33] or chalcogenbased electrophiles [34,35], or under photocatalysis and electrochemistry conditions involving radical intermediates, has been well documented [36,37]. Traditionally, these cyclization reactions are conducted for alkenes and alkynes neighboring nucleophilic substituents at an appropriate position, which can limit the applicability as most of them are not readily available starting materials, owing to its obtaining of a transition-metal catalysis in at least one reaction step.…”

Direct Electrooxidative Selenylation/Cyclization of Alkynes: Access to Functionalized Benzo[b]furans

“…Over the past few decades, some significant progress has been made in the field of synthesis of organoselenium compounds [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ] as well as benzofurans. Most of the transformations were traditionally utilized transition-metal catalysts or stoichiometric amounts of oxidants.…”