Photoredox Catalytic Pentafluorosulfanylative Domino Cyclization of α-Substituted Alkenes to Oxaheterocycles by Using SF6_{6}

Virtually inert sulfur hexafluoride becomes a precious pentafluorosulfanylation agent, if properly activated by photoredox catalysis, to access α-fluoro and α-alkoxy SF$_{5}$-compounds. This advanced protocol converts SF$_{6}$ in the presence of alkynols as bifunctional C−C- and C−O-bond forming reagents directly into pentafluorosulfanylated oxygen-containing heterocycles in a single step from α-substituted alkenes. The proposed mechanism is supported by theoretical calculations and gives insights not only in the pentafluorosulfanylation step but also into formation of the carbon-carbon bond and is in full agreement with Baldwin\u27s cyclization rules. The key step is a radical type 5-, 6- respectively 7-exo-dig-cyclization. The synthesized oxaheterocycles cannot be simply prepared by other synthetic methods, show a high level of structural complexity and significantly expand the scope of pentafluorosulfanylated building blocks valuable for medicinal and material chemistry

Heterobimetallic Gold/Ruthenium Complexes Synthesized via Post‐functionalization and Applied in Dual Photoredox Gold Catalysis

The synthesis of heterobimetallic AuI/RuII complexes of the general formula syn- and anti-[{AuCl}(L1∩L2){Ru(bpy)$_{2}$}][PF$_{6}$]$_{2}$ is reported. The ditopic bridging ligand L1∩L2 refers to a P,N hybrid ligand composed of phosphine and bipyridine substructures, which was obtained via a post-functionalization strategy based on Diels-Alder reaction between a phosphole and a maleimide moiety. It was found that the stereochemistry at the phosphorus atom of the resulting 7-phosphanorbornene backbone can be controlled by executing the metal coordination and the cycloaddition reaction in a different order. All precursors, as well as the mono- and multimetallic complexes, were isolated and fully characterized by various spectroscopic methods such as NMR, IR, and UV-vis spectroscopy as well as cyclic voltammetry. Photophysical measurements show efficient phosphorescence for the investigated monometallic complex anti-[(L1∩L2){Ru(bpy)$_{2}$}][PF$_{6}$]$_{2}$ and the bimetallic analogue syn-[{AuCl}(L1∩L2){Ru(bpy)$_{2}$}][PF$_{6}$]$_{2}$, thus indicating a small influence of the {AuCl} fragment on the photoluminescence properties. The heterobimetallic Au$^{I}$/Ru$^{II}$ complexes syn- and anti-[{AuCl}(L1∩L2){Ru(bpy)$_{2}$}][PF$_{6}$]$_{2}$ are both active catalysts in the P-arylation of aryldiazonium salts promoted by visible light with H-phosphonate affording arylphosphonates in yields of up to 91 %. Both dinuclear complexes outperform their monometallic counterparts

Multistimuli‐Responsive [3]Dioxaphosphaferrocenophanes with Orthogonal Switches

Novel multistimuli-responsive phosphine ligands comprising a redox-active [3]dioxaphosphaferrocenophane backbone and a P-bound imidazolin-2-ylidenamino entity that allows switching by protonation are reported. Investigation of the corresponding metal complexes and their redox behaviour are reported and show the sensitivity of the system towards protonation and metal coordination. The experimental findings are supported by DFT calculations. Protonation and oxidation events are applied in Rh-catalysed hydrosilylations and demonstrate a remarkable influence on reactivity and/or selectivity

Synthesis of Thiophene‐fused Helicenes

The synthesis of three penta- and three hexahelicenes containing two terminal thiophene units is described. The syntheses of pentahelicenes consist of 1,4-bisalkynylation of a benzene precursor and double Suzuki coupling in 2,3-position to introduce thiophene units. The ortho,ortho’ fusion yielding the final products was achieved with Fürstner\u27s protocol using platinum(II) chloride or JohnPhos-complexed gold(I) as catalysts. A similar approach to hexahelicenes started with a naphthalene derivative, where 2,7-bisalkynylation and subsequent double Suzuki coupling with thiophene-2-boronic acid at 1,8-position furnished precursors, in which ortho,ortho’ fusion to the respective hexahelicenes was achieved with platinum(II) chloride or, favourably, with indium(III) chloride. UV/Vis spectra and cyclic voltammograms were recorded for all helicenes and HOMO/LUMO gaps were calculated with DFT methods

Photoredox Catalytic Pentafluorosulfanylative Domino Cyclization of α-Substituted Alkenes to Oxaheterocycles by Using SF6

Virtually inert sulfur hexafluoride becomes a precious pentafluorosulfanylation agent, if properly activated by photoredox catalysis, to access α-fluoro and α-alkoxy SF5-compounds. This advanced protocol converts SF6 in the presence of alkynols as bifunctional C−C- and C−O-bond forming reagents directly into pentafluorosulfanylated oxygen-containing heterocycles in a single step from α-substituted alkenes. The proposed mechanism is supported by theoretical calculations and gives insights not only in the pentafluorosulfanylation step but also into formation of the carbon-carbon bond and is in full agreement with Baldwin's cyclization rules. The key step is a radical type 5-, 6- respectively 7-exo-dig-cyclization. The synthesized oxaheterocycles cannot be simply prepared by other synthetic methods, show a high level of structural complexity and significantly expand the scope of pentafluorosulfanylated building blocks valuable for medicinal and material chemistry.ISSN:0947-6539ISSN:1521-376

Photoredox Catalytic Pentafluorosulfanylative Domino Cyclization of α‐Substituted Alkenes to Oxaheterocycles by Using SF 6

Virtually inert sulfur hexafluoride becomes a precious pentafluorosulfanylation agent, if properly activated by photoredox catalysis, to access α-fluoro and α-alkoxy SF$_{5}$-compounds. This advanced protocol converts SF$_{6}$ in the presence of alkynols as bifunctional C−C- and C−O-bond forming reagents directly into pentafluorosulfanylated oxygen-containing heterocycles in a single step from α-substituted alkenes. The proposed mechanism is supported by theoretical calculations and gives insights not only in the pentafluorosulfanylation step but also into formation of the carbon-carbon bond and is in full agreement with Baldwin\u27s cyclization rules. The key step is a radical type 5-, 6- respectively 7-exo-dig-cyclization. The synthesized oxaheterocycles cannot be simply prepared by other synthetic methods, show a high level of structural complexity and significantly expand the scope of pentafluorosulfanylated building blocks valuable for medicinal and material chemistry