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Iron(0)‐Mediated Stereoselective (3+2)‐Cycloaddition of Thiochalcones via a Diradical Intermediate
Author(s) -
Buday Philipp,
Seeber Phillip,
Zens Clara,
AbulFutouh Hassan,
Görls Helmar,
Gräfe Stefanie,
Matczak Piotr,
Kupfer Stephan,
Weigand Wolfgang,
Mloston Grzegorz
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202001412
Subject(s) - diradical , cycloaddition , chemistry , intramolecular force , stereocenter , homolysis , bond cleavage , adduct , stereoselectivity , molecule , stereochemistry , medicinal chemistry , photochemistry , radical , catalysis , organic chemistry , enantioselective synthesis , singlet state , physics , nuclear physics , excited state
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.