Visible‐Light‐Mediated Liberation and In Situ Conversion of Fluorophosgene. Issue 1 (9th November 2018)

• Record Type: Journal Article
• Authors: Petzold, Daniel; Nitschke, Philipp; Brandl, Fabian; Scheidler, Veronica; Dick, Bernhard; Gschwind, Ruth M.; König, Burkhard
• Is Part Of: Chemistry. Volume 25:Issue 1(2019)
• Page Start: 361
• Page End: 366
• Publication Date: 2018-11-09
• Subjects: CT-complex -- fluorophosgene -- NMR spectroscopy -- photocatalysis -- trifluoromethoxyarenes; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201804603
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The first example for the photocatalytic generation of a highly electrophilic intermediate that is not based on radical reactivity is reported. The single‐electron reduction of bench‐stable and commercially available 4‐(trifluoromethoxy)benzonitrile by an organic photosensitizer leads to its fragmentation into fluorophosgene and benzonitrile. The in situ generated fluorophosgene was used for the preparation of carbonates, carbamates, and urea derivatives in moderate to excellent yields via an intramolecular cyclization reaction. Transient spectroscopic investigations suggest the formation of a catalyst charge‐transfer complex‐dimer as the catalytic active species. Fluorophosgene as a highly reactive intermediate, was indirectly detected via its next downstream carbonyl fluoride intermediate by NMR. Furthermore, detailed NMR analyses provided a comprehensive reaction mechanism including a water dependent off‐cycle equilibrium. Abstract : Fluorophosgene was liberated by the photocatalytic reduction of a simple aryltrifluoromethoxyether. This highly reactive species was used for the synthesis of cyclic carbonates, carbamates and urea derivatives. The reaction mechanism was investigated by an in‐depth NMR study as well as cyclovoltammetry and transient spectroscopy which suggests a charge‐transfer complex dimer as the catalytic active species.