Iron(0) mediated stereoselective (3+2)-cycloaddition of thiochalcones via a diradical intermediate.

Iron(0) mediated stereoselective (3+2)-cycloaddition of thiochalcones via a diradical intermediate.
Chemistry. 2020 Mar 25;:
Authors: Mloston G, Buday P, Seeber P, Neumann C, Abul-Futouh H, Görls H, Gräfe S, Matczak P, Kupfer S, Weigand W
Abstract
Reactions of α,β-unsaturated aromatic thioketones 1 (thiochalcones) with Fe 3 (CO) 12 leading to η 4 -1-thia-1,3-diene iron tricarbonyl complexes 2 , [FeFe] hydrogenase mimics 3 , and the thiopyrane adduct 4 are described. Obtained products have been characterized by X-ray crystallography and by computational methods. Completely regio- and diastereoselective formation of the five-membered ring system in products 3 , containing four stereogenic centers, can be explained by an unprecedented, stepwise (3+2)-cycloaddition of two thiochalcone molecules mediated by Fe 3 (CO) 12 . Quantum chemical calculations, aimed at elucidation of the reaction mechanism, suggest that the formal (3+2)-cycloaddition proceeds via sequential intramolecular radical transfer events upon homolytic cleavage of one carbon-sulfur bond leading to a diradical intermediate.
PMID: 32212185 [PubMed - as supplied by publisher]

Source: Chemistry - March 24, 2020 Category: Chemistry Authors: Mloston G, Buday P, Seeber P, Neumann C, Abul-Futouh H, Görls H, Gräfe S, Matczak P, Kupfer S, Weigand W Tags: Chemistry Source Type: research