Recyclable and reusablen-Bu₄NBF₄/PEG-400/H₂O system for electrochemical C-3 formylation of indoles with Me₃N as a carbonyl source

Abstract

An eco-friendly electrochemical C-3 formylation of indoles using Me3N as a carbonyl donor in a recyclable reaction medium has been developed.

Rongalite in PEG-400 as a general and reusable system for the synthesis of 2,5-disubstituted chalcogenophenes

“…Rongalite (sodium hydroxymethanesulfinate) is a safe, non-toxic and cheap reagent with recognized reducing properties, 36 which has been explored in organochalcogen chemistry as a reducing agent of Y 0 (Y = Se, Te) 37 and diorganoyl dichalcogenides, 38 under operationally simple reaction conditions. Likewise, PEG-400 is a non-toxic, biodegradable and inexpensive solvent that have been successfully applied in several organic transformations 39 and in organochalcogen chemistry, 40 which was recently identified as a suitable green reaction media for reducing elemental chalcogens into their nucleophilic species. 41 Additionally, attractive recycling protocols are known for this thermally stable solvent.…”

“…41 Additionally, attractive recycling protocols are known for this thermally stable solvent. 39,40 Until now, this has been an unexplored area in the synthesis of chalcogenophenes by sustainable chemical methods.…”

A stable and recyclable Z-scheme g-C3N4/rGO/BiVO4 heterojunction photocatalyst for site-selective C-3 formylation of indoles with methanol as a formyl source under visible light

“…To overcome these shortcomings, various alternative formylating reagents were developed for the C-3 formylation of indoles under photochemical, electrochemical and thermochemical conditions. The first type was amines, such as N , N -dimethylaminoethanol, 8 N -methylaniline, 9 N , N -dimethylaniline, 10 tetramethylethylenediamine (TMEDA), 11 hexamethylenetetramine (HMTA) 12 and trimethylamine 13 (Scheme 1b). The second type was carbonyl compounds, for instance, glyoxylic acid, 14 HCOOH, 15 HCHO (aq.)…”

Electrosynthesis of amino acids from biomass-derived α-hydroxyl acids

“…Compared to all the reported processes, electrosynthesis has been regarded as a sustainable and efficient method, as it does not require any external oxidants/reductants and is usually carried out under ambient conditions. [18][19][20] Indeed, electrochemical reductive amination has been reported for the synthesis of amino acids from α-keto acids in a flow electrolyzer when NH 2 OH was employed as the nitrogen source. 21 In this case, the counter reaction is water oxidation and IrO 2 was used as the anode to drive the oxygen evolution reaction (OER).…”

“…Compared to all the reported processes, electrosynthesis has been regarded as a sustainable and efficient method, as it does not require any external oxidants/reductants and is usually carried out under ambient conditions. 18–20…”