Iron(0)-Mediated Stereoselective (3+2)-Cycloaddition of Thiochalcones via a Diradical Intermediate

Synthesis of Bicyclic P,S-Heterocycles via the Addition of Thioketones to a Phosphorus-Centered Open-Shell Singlet Biradical

Formal addition reactions between the open-shell singlet biradical [P(μ-NTer)]₂ (1Ter) and xanthione, thioxanthione, as well as ferrocenyl naphthyl thioketone were studied in detail. Reactions were performed at room temperature and led to the formation of strained [2.1.1]-cage P,S-heterocycles (3). All addition products were isolated and fully characterized by spectroscopic methods. Furthermore, reversible cleavage of the xanthenthione-biradical addition product into the parent compounds (biradical and thioketone) could be demonstrated by ³¹P{¹H} NMR spectroscopy. The thermodynamic stability of all cyclization products with respect to the elimination of thioketone was studied by quantum-chemical computations including solvent effects. Regarding the dissociation of addition products 3 into the fragment molecules 1Ter and ketone/thioketone, calculations prove that a significantly larger distortion energy in ketones compared with thioketones causes lower thermodynamic stability of the ketone adducts.

Metal–ligand bonding in tricarbonyliron(0) complexes bearing thiochalcone ligands

Bonding interactions between iron and thiochalcones in a series of recently synthesized complexes were analyzed using various theoretical methods.

Cooperative Photoinduced/Brønsted Acid Catalyzed Cycloaddition of Transient Thioaldehydes and ortho-Quinone Methides toward a Synthesis of Benzo[e][1,3]oxathiines

A cooperative, one-pot approach for the in situ generation and ensuing cycloaddition of thioaldehydes and ortho-quinone methides transiently formed under irradiation with UV-A light and Brønsted acid catalysis, respectively, has been developed giving direct access to benzo[e][1,3]oxathiines in good to excellent yields and diastereoselectivity. Both electron-rich and electron-poor thioaldehydes easily react with a broad range of ortho-quinone methides at ambient temperature in a short reaction time to furnish a wide variety of S,O-heterocycles.