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Synthesis and properties of push-pull imidazole derivatives with application as photoredox catalysts

Authors: Hloušková Zuzana | Bureš Filip

Year: 2017

Type of publication: článek v odborném periodiku

Name of source: ARKIVOC

Page from-to: 330-342

Titles:

Language	Name	Abstract	Keywords
cze	Syntéza a vlastnosti push-pull derivátů imidazolu využitelných jako fotoredoxní katalyzátory	Byly připraveny dvě nové push-pull molekuly nesoucí imidazol-4,5-dikarbonitril jako akceptor a thiofen resp. 2-methoxythiofen jako donor, molekuly byly designovány pro použití ve fotoredoxní katalýze. Komerčně dostupný imidazol-4,5-dikarbonitril byl nejprve bromován a N-methylován. Následnou Suzukiho-Miyaurovou cross-couplingovou reakcí s thiofen- resp. 5-methoxythiofenboronovou kyselinou byly připraveny cílové produkty. Struktura látek byla potvrzena obvyklými analytickými metodami, struktura 5-methoxythiofenového derivátu byla potvrzena X-ray analýzou. Termánlí stabilitu potvrdily DSC analýzy. Vlastnosti látek byly rovněž studovány pomocí UV-VIS absorpční spektroskopie a byly provedeny DFT kalkulace. Obě molekuly byly testovány jako fotoredoxví katalyzátory cross-dehydrogenačního couplingu tetrahydroisochinolinu s nitromethanem.	imidazol-4,5-dikarbonitril; push-pull; fotoredoxní katalýza; cross-dehydrogenační coupling
eng	Synthesis and properties of push-pull imidazole derivatives with application as photoredox catalysts	Two new push-pull molecules with imidazole-4,5-dicarbonitrile acceptor, thiophene and 2-methoxythiophene donors with potential use in photoredox catalysis were designed and prepared. The synthesis started from commercially available imidazole-4,5-dicarbonitrile and its bromination and N-methylation. Subsequent Suzuki-Miyaura cross-coupling with (5-methoxy)thiophene-derived boronic acids afforded target push-pull derivatives. Beside common analytical methods, the molecular structure of 5-methoxythiophen-2-yl derivative has also been verified by X-ray analysis. DSC analyses showed remarkable thermal stabilities of both target derivatives with T-m and T-D values above 150 and 270 degrees C, respectively. Fundamental properties and extent of the intramolecular charge-transfer were further studied by UV-VIS absorption spectra and DFT calculations. Fundamental photoredox properties of target imidazole derivatives were elucidated. Both push-pull molecules were preliminary tested as photoredox catalysts in cross-dehydrogenative coupling reaction between tetrahydroisoquinoline and nitromethane and the results were compared with those obtained by pyrazine2,3-dicarbonitrile-derived catalyst.	Imidazole-4,5-dicarbonitrile; push-pull; photoredox catalysis; cross-dehydrogenative coupling