Synthesis of 3-selanylbenzo[b]furans promoted by SelectFluor®

Abstract

A simple and practical protocol for the synthesis of 3-selanyl-benzo[b]furans mediated by the SelectFluor® reagent was developed. This novel methodology provided a greener alternative to generate 3-substitutedbenzo[b]furans via a metal-free procedure under mild conditions. The intramolecular cyclization reaction was carried out employing an electrophilic selenium species generated in situ through the reaction between SelectFluor® and organic diselenides. The formation of this electrophilic selenium species (RSe-F) was confirmed by heteronuclear NMR spectroscopy, and its reactivity was explored. Scheme 2 Substrate scope for the synthesis of 3-organylselanylbenzo[b]furans 3a-k. Scheme 3 Chalcogenide scope for the synthesis of 3-chalcogenylbenzo[b]furans 3l-m.This journal is Scheme 7 Plausible mechanism routes for the synthesis of 3-organylselanyl-benzo[b]furans 3.This journal is

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

“…Furthermore, we alternatively reported our results on the use of Selectfluor ® as a mild oxidant to generate electrophilic selenium species for cyclization reactions. [50] In this sense, oalkynylanisoles reacted with diorganyl diselenides in the presence of the oxidant in acetonitrile furnishing eleven 3selenylbenzo[b]furans 55 in 40 % to 97 % yields (Scheme 30). In addition, the preparation of 3-(phenylthio)-and 3-(phenyltellanyl)-benzo[b]furans was obtained in 44 % and 30 % yields, respectively.…”

Insights into the Recent Synthetic Advances of Organoselenium Compounds

“…A different metal‐free arylselenocyclization method using PhSeF was developed by Silva et al ., [61] wherein atom economy was achieved in milder conditions. PhSeF has been a highly reactive electrophilic selenium intermediate obtained in situ from reaction of diphenyl diselenides and SelectFluor® reagent.…”

“…of SelectFluor® and 1 equiv. of diorganyl diselenides, route A is preferred, whereas route B is favoured if both the reagents were used in 1 equiv [61] …”

“…of diorganyl diselenides, route A is preferred, whereas route B is favoured if both the reagents were used in 1 equiv. [61] The cooperative action between diorganyl dichalcogenides and iron(III) chloride has found its credibility in the generation of chalcogen-heterocycles. [62][63][64][65][66] Unsaturated substrates such as, N,N-dimethyl-2-alkynylanilines, ortho-diynyl benzyl chalcogenides, N-arylpropargylamines, thiopropargyl benzimidazoles are cyclized with diselenides using iron catalysts.…”

Oxidative Three-Component Selenofunctionalization of Alkenes: Convenient Access to Vicinally Functionalized Selenides

“…Regarding organoselenium chemistry, the generation of an electrophilic selenium species using an N–F reagent was reported by Breder and Zhao, respectively. Since then, the use of N–F reagents to generate electrophilic selenium species has become an attractive method for selenenylation of alkenes . Very recently, we reported an intermolecular carboselenenylation of olefins with aromatics and diselenides that used N-fluorobenzenesulfonimide (NFSI) as the terminal oxidant (Scheme a) .…”