Univerzita Pardubice Fakulta chemicko- technologická

Univerzita Pardubice

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Studenti
English

Publikace detail

DiCyanoPyrazine: New and highly efficient organic photoredox catalyst.

Autoři: Bureš Filip

Rok: 2018

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
eng	DiCyanoPyrazine: New and highly efficient organic photoredox catalyst.	Photoredox catalysis is currently considered as a reliable and renascent tool used for the construction of chemical bonds. Visible light-induced chemical transformations are generally carried out under very mild conditions without presence of an external energy source (except the light). Beside well-known and explored organometallic species such as ruthenium and iridium polypyridine complexes, such transformation may also be catalyzed by organic substances. Xanthene dyes are the most common representatives, however these suffer from relatively rigid structure, which disallows further property tuning. Hence, the current interest of the community is directed towards synthetic dyes. Based on our recent investigation on pyrazine-derived X-shaped push-pull molecules, we have recently developed a new DiCyanoPyrazine (DCP) derivative bearing 5 methoxythiophen-2-yl electron donors. This molecule possesses broad absorption of visible light and redox properties well tailored for photoredox catalysis as demonstrated in few challenging reactions (cross-dehydrogenative coupling, oxidations, and dehalogenations). Moreover, we have also demonstrated high activity of this catalyst even at very low loadings (0.01 mol%). Further studies showed that the aforementioned DCP derivative may catalyze unprecedented chemodivergent radical cascade reactions between N tetrahydroisoquinolines and N itaconimides affording four different products via addition-cyclization, addition-elimination, addition-coupling, and addition-protonation pathways. The reaction can be directed towards the desired product via controlling the process by additives, solvent, and temperature. The catalyst has further been tested in aerobic photooxygenation of indoles providing either isatins or formylformanilides. The process can easily be controlled by pH. Cooperative photoredox and asymmetric catalysis has been proved in enantioselective oxidative C(sp3)-H olefinations of tetrahydro--carbolines and N tetrahydroisoqui	dicyanopyrazine; photoreox catalyst; oxidative olefination