Electrochemical Annulations of o-Alkynylanilines for Synthesis of 3-Iodoindoles

Abstract

( a 南京林业大学化学工程学院 江苏省林业资源高效加工利用协同创新中心 南京 210037)

Recent advances in electrochemically enabled construction of indoles from non-indole-based substrates

“…18 In 2021, our group reported an example of the electrochemical annulation of o-alkynylanilines for the synthesis of 3-iodoindoles (Scheme 5, top). 19 This reaction utilized TBAI's triple role of an electrolyte, a redox catalyst, and the iodine source, resulting in a Scheme 3 Electrochemical intramolecular annulation of 2-alkynylanilines to access indoles and indolines. 16 Scheme 2 Electrochemical intramolecular annulation of (hetero)arylamines with tethered alkynes.…”

Paired Electrolysis Enabled Cyanation of Diaryl Diselenides with KSCN Leading to Aryl Selenocyanates

“…In comparison with the traditional methods that often proceed at strong oxidative or reductive conditions with elevated temperature or pressure in the presence of chemical oxidizing agents or reducing agents, electrochemical reactions are usually carried out under milder conditions by precisely varying the applied electrode potential. Therefore, electrosynthesis is usually compatible with highly functionalized substrates and has displayed great potential in both synthetic and bioconjugation chemistry [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. In recent years, electrochemical cyanation with various cyanating agents (trimethylsilyl cyanide [ 42 , 43 , 44 , 45 , 46 ], cyanobenziodoxolone [ 47 ], AIBN [ 48 ], tosyl cyanide [ 49 ] and 4-cyanopyridine [ 50 ]) have been used to construct the cyanated products.…”

Electrochemical Synthesis of 3-Sulfonylindoles via Annulation of o-Alkynylanilines with Sodium Sulfinates

“…Without Et3N, the desired product 3a was only isolated in 54% yield, companying with by-product 3-iodoindole 3a' in 31% yield after 6 h (Figure S5, Supporting Information). [16] In comparison, the addition of Et3N could efficiently inhibit the formation of 3a'. Under the standard conditions, the desired product 3a was isolated in 83% yield with 12% yield of 3a' (entries 12).…”

“…Notably, terminal alkynes bearing different substituted aniline groups were also converted effectively to 3-sulfonylindoles 3u-3y. Since 3-iodoindoles could not be produced from terminal alkynes according to previous work, [16] Et3N was not required here.…”