5<i>H</i>‐[1]Benzoselenino[2,3‐<i>b</i>]pyridin – ein neues heterocyclisches Ringsystem

By way of a photo‐induced selenolester‐seleninone rearrangement, the derivative 5 of a new heterocyclic ring system, 9H‐cyclopenta[b][1]benzoselenin, has been formed. This rearrangement occurs via a new photosubstitution reaction of S‐aryl‐ in competition with Se‐aryl‐groups, followed by photocyclization using 2‐p ‐tolythiocyclopentene ‐1 ‐ selenocarbonic acid Se‐p‐tolylester (1a) as starting materials. As a competing product in this photo‐rearrangement, a second heterocycle, 7‐methylcyclopenta[b] [1]benzothiopyrone (4) (9) has been formed via an intramolecular photochemical Friedel Crafts reaction.

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Organische Photochemie, XXX. Notiz über einen neuen Weg zum 4‐Azaxanthon

Beelitz

Praefcke

1979

Liebigs Ann. Chem.

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Es wird die Synthese des pharmazeutisch interessanten 4-Azaxanthon-Ringsystems 3 unter neutralen Bedingungen durch UV-Bestrahlung des 2-Chlornicotinsaure-arylesters 1 beschrieben. Die Verbindung 3 entsteht uber das Photo-Fries-Produkt 2, das sowohl thermisch bei hoheren Temperaturen als auch photochemisch unter Abspaltung von Chlorwasserstoff cyclisiert. In vie1 kleinerer Ausbeute wird 3 auch durch Fries-Umlagerung von 1 mit Aluminiumtrichlorid gebildet. Organic Photochemistry, XXX'). -Note on a Novel Route to 4-AzaxanthoneThe synthesis of the pharmaceutically interesting 4-azaxanthone ring system 3 under neutral conditions by UV irradiation of the aryl2-chloronicotinate 1 is described. Compound 3 is formed via the photo-Fries product 2, which cyclizes thermally at higher temperatures as well as photochemically by elimination of hydrogen chloride. Compound 3 is also produced in much lower yield by Fries rearrangement of 1 with aluminium chloride.4-Azaxanthon-Derivate besitzen pharmazeutisches Interesse2-4) und werden bisher iiblicherweise durch Cyclisierung von 2-Aryloxynicotinsauren synthetisiert, die ihierseits durch Kondensation entsprechender 2-Chlornicotinsaure-und Phenol-Abkbmmlinge zuganglich ~i n d~.~,~) .In Fortsetzung unserer Arbeiten iiber photochemische Heterocyclen-Synthesen6) berichten wir hier iiber einen neuen Zugang zum 4-Azaxanthon-System aus 2-Chlornicotinsaure-arylestern. So erhalt man aus 1 durch Photo-Fries-Umlagerung unter anderem das bisher unbekannte Hydroxyketon 2. A l s weiteres Photoprodukt isoliert man das 4-Azaxanthon 3.

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5H‐[1]Benzoselenino[2,3‐b]pyridin – ein neues heterocyclisches Ringsystem

Cited by 10 publications

References 4 publications

ChemInform Abstract: ORGANIC SELENIUM COMPOUNDS. 4. 5H‐(1)BENZOSELENINO(2,3‐B)PYRIDINE ‐ A NEW HETEROCYCLIC RING SYSTEM

ChemInform Abstract: ORGANIC SELENIUM COMPOUNDS. 4. 5H‐(1)BENZOSELENINO(2,3‐B)PYRIDINE ‐ A NEW HETEROCYCLIC RING SYSTEM

Organische photochemie XXI. 9H‐cyclopenta[b] [1]benzoselenin ‐ein neues heterocydisches ringsystem

Organische Photochemie, XXX. Notiz über einen neuen Weg zum 4‐Azaxanthon

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