Dien‐katalysierte Photo‐Dimerisierung über Excimere (Exciplexe) oder Dienaddition an Anthracen und 9‐Phenylanthracen?
1980; Wiley; Volume: 113; Issue: 11 Linguagem: Inglês
10.1002/cber.19801131126
ISSN0009-2940
Autores Tópico(s)Analytical Chemistry and Chromatography
ResumoDiene‐Catalyzed Photodimerization via Excimers (Exciplexes) or Diene Addition to Anthracene and 9‐Phenylanthracene The [4 + 4]‐photodimerization of anthracene ( 1 ) is not enhanced by 2,4‐hexadiene ( 3 ) but impeded due to formation of [4 + 2]‐ ( 4 ) and [4 + 4]‐adducts ( 5, 6 ). 6 and 1 combine to give the bisadduct 7 at room temperature. The selective photolysis of 9‐phenylanthracene ( 8 ) leads to the anti ‐[4 + 4]‐dimer ( 9 ). This can be compared with the [4 + 4]‐photodimerization of 9‐methylanthracene which affords the anti ‐ and the thermolabile syn ‐product. 1,3‐Dienes such as 1,3‐pentadiene ( 10 ) or 1,3‐cyclohexadiene ( 13 ) are not necessary for the formation of 9 but undergo cycloadditions with 8 to yield [4 + 2]‐ ( 11 , 12 , 14 ), [4 + 4]‐ ( 15 ), and [2 + 2]‐adducts ( 16, 17 ). The structures of the products are established primarily by high field 1 H‐NMR spectroscopy.
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