Synthesis and Structures of Polyphenylphenanthrenes |
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Authors: | Dr Yonglong Xiao Prof Joel T Mague Prof James P Donahue Dr Laura J Wilson Dr Christina M Kraml Prof Robert A Pascal Jr |
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Institution: | 1. Department of Chemistry, Tulane University, New Orleans, LA, 70118 USA;2. Lotus Separations LLC, Princeton, NJ, 08544 USA |
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Abstract: | 1,2,3,4,5,6,7,8-Octaphenylphenanthrene ( 4 ) and decaphenylphenanthrene ( 5 ) were prepared by very short syntheses (two or three steps) from tetraphenylfuran and polybrominated benzene derivatives. The X-ray structures of compounds 4 and 5 show them to be quite crowded, with the phenanthrene cores twisted by about 40° due to the clash of the C4 and C5 phenyl groups. Compound 4 was resolved by chromatography on a chiral support, and its free energy of activation for racemization was determined to be 24.6 kcal mol?1 at 40 °C. Computational studies indicate that compound 5 has a racemization barrier approximately 6 kcal mol?1 lower than 4 , and thus 5 would not be configurationally stable at room temperature. |
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Keywords: | arenes polycyclic aromatic hydrocarbons polyphenyl aromatic compounds strained molecules |
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