Face-Selective Diels−Alder Reactions between Unsymmetrical Cyclohexadienes and Symmetric <i>trans</i>-Dienophile: An Experimental and Computational Investigation
作者:Saswati Lahiri、Somnath Yadav、Srirupa Banerjee、Mahendra P. Patil、Raghavan B. Sunoj
DOI:10.1021/jo701884d
日期:2008.1.1
functional theory studies with the mPW1PW91/6-31G* as well as the B3LYP/6-31G* levels reveal that the electrostatic repulsion between the oxygen lone pairs on the diene and the dienophile is critical to the observed product selectivities. The optimized transition state geometries though appeared to involve secondary orbital interactions, careful examination of the frontier Kohn−Sham orbitals as well as calculations
2-三甲基甲硅烷基-1,3-环己二烯(间的合成的实验和理论研究的狄尔斯-阿尔德反应的2 - 11)和(Ë)-1,4-二苯基丁-2-烯-1,4-二酮(1)被报道。两个非对映体的产品,5 -内6 -exo-(NX)和5 -exo- 6 -内(XN)二苯甲酰基衍生物,是可能具有对称的反式-dienophile(1)。虽然在许多情况下,5 -内6 -外产物优于相应的5- -exo- 6 -内乘积,乘积比nx:xn发现R 1与R 2随二烯上取代基的位置而变化。对mPW1PW91 / 6-31G *和B3LYP / 6-31G *浓度的密度泛函理论研究表明,二烯上的氧孤对与亲二烯体之间的静电排斥对观察到的产物选择性至关重要。优化的过渡态几何形状似乎涉及次级轨道相互作用,对前沿科恩-沙姆轨道的仔细检查以及使用自然键轨道(NBO)分析的计算证实了在这些过渡态中不存在SOI。在甲基取代的二烯的情况下,发现二