The rotational barriers around an N-(2-F)C6H4 bond in 2-aryl-3-(2-fluorophenyl)quinazolin-4-ones considerably lowered (ca. 4 kcal mol-1 lower) in comparison with those of 2-alkyl-3-(2-fluorophenyl)quinazolin-4-ones. The transition state structure estimated by the DFT calculation indicates that the considerable decrease in the rotational barriers in 2-aryl derivatives is caused by the alleviation of the steric repulsion between an ortho-substituent of 2-fluorophenyl group and 2-aryl group.

中文翻译：

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2-芳基-3-（2-氟苯基）喹唑啉-4-一衍生物的旋转稳定性研究

与那些芳基相比，在2-芳基-3-（2-氟苯基）喹唑啉-4-酮中的N-（2-F）C 6 H 4键周围的旋转势垒大大降低（降低约4 kcal mol -1 ） 2-烷基-3-（2-氟苯基）喹唑啉-4-酮 通过DFT计算估计的过渡态结构表明2-芳基衍生物的旋转势垒的显着降低是由2-氟苯基和2-芳基的原取代基之间的空间排斥的减轻引起的。