Catalyst‐Triggered Highly Selective C−S and C−Se Bond Formation by C−H Activation

Abstract

Nickel or iron salts catalyzing the selective synthesis of 3,3‐indolyl disulfide (diselenide) and 3,3‐indolyl thioether (selenide) directly from indole through C−H activation are reported. The effect of iodine element was beneficial in the novel metal‐catalyzed circulation system. A wide variety of functional groups could be tolerated under the reaction conditions.

A Study on the Reactions of SeO2 with Pyrroles and N‐Substituted Indoles in Non‐Anhydrous Ethanol under Non‐Inert Atmosphere

“…Free indole 1 e reacted smoothly under same reaction condition to give the corresponding product 3 e , in 62% yield (entry 5). The analytical data exactly matched with literature report.…”

“…On the other hand, a handful of reports are known for the synthesis of 3,3′‐diindolyl selenides with very limited number of N‐protected indole substrates scope only ,. The few known procedures suffer drawbacks like involvement of expensive catalyst and the use of hazardous and extremely carcinogenic aromatic solvent in some rudimentary reports . And the reported synthesis of unsymmetric indole‐3‐selenides often use obnoxious diaryl diselenides assisted with other redox reagents ,.…”

Insights into the Recent Synthetic Advances of Organoselenium Compounds

“…Selenofunctionalization results in formation of C−Se bond which is prevelant in organic synthesis with pharmaceutical applications. It has been achieved through different means such as transition‐metal catalyzed coupling/cross‐coupling and addition reactions, [88a,b] iodine‐catalyzed reactions, [88c,d] Ni‐based nanocatalyst assisted regioselective addition reaction [88e] . Selenylated compounds can further act as viable intermediates for further transformations in complex synthetic schemes as witnessed in stereoselective synthesis of nucleosides and nucleotides [88f] …”

Metal‐Free Synthesis of Unsymmetrical Aryl Selenides and Tellurides via Visible Light‐Driven Activation of Arylazo Sulfones

“…For this aim, the development of an efficient and versatile synthetic protocol for the preparation of aryl selenides and tellurides is a challenge in organic chemistry, and in most cases, the intermediacy of a transition metal catalyst is required. [14] An overview of the recent literature pointed out that such derivatives can be obtained from a variety of aromatic substrates including haloarenes (mainly aryl iodides) [15][16][17][18][19][20] aryltrialkoxysilanes, [21] triarylbismuthanes [22,23] aryl boronic acids, [24][25][26][27] and even unfunctionalized aromatics [28] under Cu-, [15][16][17][18][20][21][22][23][24][25] Pd-, [26] Ni-, [21] Fe-, [21] Ru- [19] and Ag- [26,27] catalysis (an example in Scheme 1a). As for the chalcogen source, apart from elemental selenium, [22,23] selenolate and tellurolate anions, [29] diselenides and ditellurides are considered as the elective choice, [30] also in view (in the case of diselenides) of the rather low toxicity and radicals under both photocatalyst-and additive-free conditions.…”