Multistep Synthesis of Organic Selenides under Visible Light Irradiation: A Continuous-Flow Approach

Abstract

The potential application of multistep continuous-flow systems has had a great impact on the syntheses of active pharmaceutical ingredients, natural products, and commodity chemicals. In this report, the highly efficient combination of a chemical reduction and a photochemical C sp 2 −H activation reaction for selenylation of biologically relevant electron-rich arenes was achieved by means of a continuous-flow process. First, the reduction of alkyl and aryl selenocyanates by Rongalite was achieved giving the corresponding diselenides; second, the photoactivation of the Se−Se bond resulted in the selenylation of electron-rich arenes, both steps from good to excellent yields. In all cases, the reaction time was shortened, and isolated yields were improved when compared to batch reaction conditions. Furthermore, connecting both reactions in a multistep continuous-flow sequence was possible even when reductive and photooxidative transformations were coupled.

“Green Is the Color”: An Update on Ecofriendly Aspects of Organoselenium Chemistry

“…Flow chemistry applied to multistep reactions could be a promising platform to apply in medicinal, agrochemical and material sciences [ 122 , 123 , 124 ]. In this way, Oksdath-Mansilla group invested its efforts in the development of a continuous flow protocol for the synthesis of valuable selenides 2 from the combination of a chemical reduction and a photochemical C(sp2)−H activation reaction ( Scheme 45 ) [ 125 ]. The first step consisted of the reduction of several selenocyanates 96 with Rongalite ® 95 to produce the corresponding diselenides in a perfluoroalkoxy (PFA) coil reactor.…”

New Dimensions in Rongalite Chemistry: The Land of Opportunities in Organic Synthesis and Material Sciences

“…In addition, very recently, Heredia et al . has employed a chemical reduction reaction for the synthesis of organic diselenides using continuous flow process . To this context, they prepared the diselenides 288 from benzyl, aryl and alkyl selenocyanates 287 by means of their reduction with rongalite in continuous‐flow reactor.…”

Light‐Mediated Seleno‐Functionalization of Organic Molecules: Recent Advances

“…A potential application resulting from the combination of flow chemistry and visible light‐mediated direct C(sp 2 )−H activation for the synthesis of 3‐selenylindoles 21 was also described by Oksdath‐Mansilla and coworkers [22] . In the presence of blue LED irradiation, the reaction of indoles 20 and diaryl diselenides 11 was conducted in a continuous flow of MeOH:H 2 O (95 : 5), affording the desired products in 2 h (Scheme 4).…”