An Evaluation of Amide Group Planarity in 7-Azabicyclo[2.2.1]heptane Amides. Low Amide Bond Rotation Barrier in Solution
作者:Yuko Otani、Osamu Nagae、Yuji Naruse、Satoshi Inagaki、Masashi Ohno、Kentaro Yamaguchi、Gaku Yamamoto、Masanobu Uchiyama、Tomohiko Ohwada
DOI:10.1021/ja036644z
日期:2003.12.1
Single-crystal X-ray diffraction structures of some relevant bicyclic amides, including the prototype N-benzoyl-7-azabicyclo[2.2.1]heptane, exhibited nitrogen-pyramidalization in the solid state. We evaluated the rotational barriers about the amide bonds of various N-benzoyl-7-azabicyclo[2.2.1]heptanes in solution. The observed reduction of the rotational barriers of the bicyclic amides, as compared with
在这里,我们表明双环 7-氮杂双环 [2.2.1] 庚烷的酰胺本质上是氮锥体。一些相关双环酰胺的单晶 X 射线衍射结构,包括原型 N-苯甲酰基-7-氮杂双环 [2.2.1] 庚烷,在固态下表现出氮锥体化。我们评估了溶液中各种 N-苯甲酰基-7-氮杂双环 [2.2.1] 庚烷的酰胺键的旋转势垒。与单环吡咯烷酰胺相比,观察到的双环酰胺旋转势垒的降低与溶液中 7-氮杂双环 [2.2.1] 庚烷酰胺的氮-锥体结构一致。发现在苯甲酰基上带有对位取代基的 N-苯甲酰基-7-氮杂双环[2.2.1]庚烷的旋转势垒的大小与哈米特'之间存在良好的相关性 s sigma(p)(+) 常数,这与解结构的相似性一致。使用密度泛函理论的计算再现了这些双环酰胺的氮-锥体结构作为能量最小值。通过应用键模型理论评估的从氮非键合 n(N) 轨道到酰胺基团的羰基 pi 轨道计算的电子离域量与各种酰胺的旋转势垒很好地相关,包括 7-氮杂双环的酰胺[2