Sodium Persulfate Mediated Selenylation of Arenofurans

Abstract

The metal‐free sodium persulfate mediated direct selenylation of arenofurans with diaryl diselenides at room temperature was developed, and the products were obtained in high yields. The reaction was found to be applicable to a variety of naphthofurans, benzofurans, and furocoumarins. To the best of our knowledge, this is the first report of the metal‐free direct selenylation of arenofurans. The experimental results suggest that the reaction proceeds through an electrophilic substitution pathway.

Selenocystine Peptides Performance in 5‐endo‐dig Reactions

“…We tested several of the most popular oxidation agents used for diselenide oxidation to see whether it is possible to employ oxidant for generation of Sec electrophile from Sec containing peptide and use it further in 5‐ endo‐dig cyclization for benzo[ b ]furan ring formation. Among the most popular oxidants for selenium electrophile generation are persulfates producing strongly electrophilic alkyl or aryl selanyl sulfate which has been proposed by Tiecco et al and proven by Kumar et al based on 77 Se NMR data , . Interestingly, Kumar et al emphasized that TFA is crucial for phenylselanyl electrophile generation in the presence of K 2 S 2 O 8 .…”

“…The most popular approaches for introduction of selenium atom in benzo[ b ]furan and indole moieties is either direct selenylation of these heterocycles or electrophilic cyclization of 2‐(1‐alkynyl)anisoles/phenols and 2‐(1‐alkynyl)anilines in the presence of selenium electrophile . The electrophilic species usually employed are arylselanyl chloride, or arylselanyl iodide generated in situ from diselenides using I 2 , Fe/I 2 , KI/ m ‐CPBA system or copper(I) iodide .…”

“…Very recently, Perin et al reported the synthesis of 2,3‐dichalcogenyl‐substituted benzo[ b ]chalcogenophenes employing oxone induced generation of selenium electrophile . Another sulfur‐containing oxidant (persulfates) induced generation of selenium electrophile has been used for the direct selenylation of indole and arenofurans . It is noteworthy that previous research has only focused on the use of simple diaryl diselenides except for Cohen et al who reported a sophisticated method, for the generation of selenocysteine, (Sec, U) electrophile.…”

Synthesis of Triazolium Inner Salts by Thiocyanation of Aldehyde‐Derived Hydrazones

“…On the basis of previous reports and our past experiences, we proposed a possible reaction mechanism (Scheme ). Thiocyanogen ( A ) is initially formed by oxidation of NH 4 SCN using (NH 4 ) 2 S 2 O 8 and subsequently undergoes electrophilic addition with 1a to produce cationic intermediate B .…”

“…Our group has recently developed an efficient method for the thiocyanation and selenylation of heterocycles . Because of the importance of both hydrazone derivatives and thiocyanation reactions, we proceeded to explore the direct C(sp 2 )–H thiocyanation of aldehyde‐derived hydrazones.…”