Influence of the Position of an Annular Nitrogen Atom on the Magnitude of the Rotational Barriers in Atropisomers of 1,8-Dihetarylnaphthalenes
作者:John A. Zoltewicz、Nobert M. Maier、Walter M. F. Fabian
DOI:10.1021/jo961825n
日期:1997.5.1
chiral 1,8-dihetarylnaphthalenes were prepared by Pd(0)-catalyzed coupling reactions. Variable-temperature proton NMR spectra show those compounds with a 2'-pyridyl or 2'-pyrazinyl ring have a much lower energy barrier for rotation to interconvert conformational isomers than those with a 3'-pyridyl ring. Coalescence temperatures may differ by as much as 100 degrees C. The results of AM1 and PM3 computations
通过Pd(0)催化的偶联反应制备了五个新的阻转异构手性1,8-二杂芳基萘。可变温度质子NMR光谱显示,具有2'-吡啶基或2'-吡嗪基环的化合物与具有3'-吡啶基环的化合物相比,具有较低的能垒以进行旋转以相互转化构象异构体。聚结温度可能相差100摄氏度。AM1和PM3的计算结果表明,σ键旋转的首选过渡态将环状氮原子置于2'或邻位,朝向第二个杂芳基环的表面,并且不朝向萘环。