Conformation and Stereodynamics of Symmetrically Ortho-Disubstituted Aryl Carbinols and Aryl Ethers
作者:Daniele Casarini、Lodovico Lunazzi、Michele Mancinelli、Andrea Mazzanti
DOI:10.1021/jo062289u
日期:2007.2.1
about the sp3−sp2 bond have been determined in a number of hindered benzyl alcohols symmetrically substituted in the ortho positions, the substituents being F, Cl, Br, and Me. The free energies of activation covered the range 4.6−10.1 kcal mol-1. Ab initio computations matched satisfactorily the trend of these values and predicted the conformation adopted by these compounds. In one case, this result could
通过使用低温动态NMR光谱,已经确定了在邻位对称取代的许多受阻苄醇中,sp 3 -sp 2键的旋转势垒,取代基为F,Cl,Br和Me 。活化的自由能覆盖4.6-10.1 kcal mol -1的范围。从头算算可以令人满意地匹配这些值的趋势,并预测这些化合物采用的构象。在一种情况下,该结果也可以通过X射线衍射结构得到证实。在相应的甲基醚的情况下,可以测量两个势垒,对应于穿过两个可区分的过渡态的通道:更高的势垒覆盖范围5.0-8.1 kcal mol -1较低的范围为4.7−6.2 kcal mol -1。