One-pot photocatalytic transformation of indolines into 3-thiocyanate indoles with new Ir(iii) photosensitizers bearing β-carbolines

Current societies demand sustainable synthetic procedures and accordingly the combination of two photocatalytic reactions in a one-pot process is a very appealing chemical tool. In the present work, we report on the development of new Ir(iii) bis-cyclometallated photosensitizers with β-carboline lig...

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Bibliographic Details
Published in:Inorganic chemistry frontiers 2021-03, Vol.8 (5), p.1253-1270
Main Authors: Sanz-Villafruela, Juan, Martínez-Alonso, Carmen, Echevarría, Igor, Vaquero, Mónica, Carbayo, Arancha, Fidalgo, Jairo, Rodríguez, Ana M, José Vicente Cuevas-Vicario, Lima, João C, Moro, Artur J, Manzano, Blanca R, Jalón, Félix A, Espino, Gustavo
Format: Article
Language:English
Subjects:
Chemical reactions
Crystallography
Electrochemical analysis
Heterocyclic compounds
Indoles
Inorganic chemistry
Oxidizing agents
Photocatalysis
Room temperature
Sustainability
Thiocyanates
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Summary:Current societies demand sustainable synthetic procedures and accordingly the combination of two photocatalytic reactions in a one-pot process is a very appealing chemical tool. In the present work, we report on the development of new Ir(iii) bis-cyclometallated photosensitizers with β-carboline ligands and disclose a simple and unprecedented photocatalytic one-pot two-step protocol for the chemoselective and C-3 regioselective oxidative thiocyanation of indolines to produce the corresponding 3-thiocyanato-indoles. The procedure is performed in THF at room temperature, in the presence of NH4SCN, O2 and the Ir(iii) photocatalysts under blue light exposure. Moreover, this methodology combines important advantages such as an outstanding efficiency, based on good yields for low catalyst loadings, along with an excellent sustainability founded on the use of O2 as a green oxidant and light as the energy source. In addition, DFT studies have allowed a clear interpretation of the photophysical and electrochemical properties of the Ir(iii) complexes and transient absorption experiments, along with other experimental proof, have demonstrated that the two photocatalytic processes are mediated by 1O2. Our results pave the way for future developments in the field of photocatalysis using Ir(iii) biscyclometallated complexes as photosensitizers.
ISSN:2052-1545
2052-1553
DOI:10.1039/d0qi01307b