Iron-Catalyzed Cyclization of Alkynols with Diorganyl Diselenides: Synthesis of 2,5-Dihydrofuran, 3,6-Dihydro-2H-pyran, and 2,5-Dihydro-1H-pyrrole Organoselanyl Derivatives

Abstract

An iron-catalyzed system, using diorganyl diselenides as an organoselenium source, was used for the cyclization of 1,4-butyne-diols in the preparation of 3,4-bis(organoselanyl)-2,5-dihydrofurans. The optimized reaction conditions are compatible with many functional groups in 1,4-butyne-diols and diorganyl diselenides. In addition, this catalyst system was also efficient with diorganyl disulfides, but it did not work for diorganyl ditellurides. The same reaction conditions were also extended to pentyne-1,5-diol for the preparation of 4,5-bis(organoselanyl)-3,6-dihydro-2H-pyrans and to 4-amino-butynol for the preparation of 2,5-dihydro-1H-pyrrole derivatives. The synthetic utility of these heterocycles was studied using 5-bis(organoselanyl)-3,6-dihydro-2H-pyrans as substrate in a Kumada-type cross-coupling reaction.

Fe3O4 Nanoparticles: A Robust and Magnetically Recoverable Catalyst for Direct C‐H Bond Selenylation and Sulfenylation of Benzothiazoles

“…Based on the above experiments and results published in the literature,,,,, two plausible mechanism for the selenylation and sulfenylation of benzothiazoles are proposed, as shown in Scheme . The first mechanistic path which proceeds via oxidative addition followed by reductive elimination is assumed (Scheme A).…”

“…There was a decrease in the yields of thiolated product 6 compared with selenium analogue 4 . This could be attributed to the stronger S−S bond of disulfides 5 in relation to the respective diselenides 3 …”

Synthesis of Seleno‐Heterocycles via Electrophilic/Radical Cyclization of Alkyne Containing Heteroatoms

“…The synthesis of selenated furan/pyrrol 43 was successfully achieved by the cyclization of 1,4-butynediol/1,4-butyne-diol-amine 42 with diorganyl dichalcogenides 4 in the presence of FeCl 3 • 6H 2 O (Scheme 14). [42] By using I 2 , ICl, Br 2 and PhSeBr as electrophile sources, the electrophilic cyclization reaction of 2chalcogenealkynyl anisole 44 was achieved and afforded the corresponding 2-chalcogen-3-substitutedbenzo[b]furan 45 with good yields. The substituents on the aromatic ring of anisole as well as chalcogen atom directly bonded to the triple bond affect the rate on reaction.…”

Emerging Organosulfonium Electrophiles as Unique Reagents for Carbon–Sulfur Bond Formation: Prospects in Synthetic Chemistry of Organosulfur Compounds

“…23 Iron-catalyzed cyclization of alkynols with PhSSPh yielded 3,4-bis(phenylthio)-2,5-dihydrofuran derivatives (Scheme 4c). 24 Another type of CS bond formation is a nucleophilic reaction with the CO bond cleavage of epoxides or carbonates. Enantioselective epoxide cleavage with RSH catalyzed by a gallium lithium chiral bis(binaphthoxide) complex was established (Scheme 4d).…”