外消旋化
菲
苯
化学
活化能
联苯
药物化学
立体化学
有机化学
作者
Yufeng Xiao,Joel T. Mague,James P. Donahue,Laura J. Wilson,Christina M. Kraml,Robert A. Pascal
标识
DOI:10.1002/chem.202001563
摘要
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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