Dudding Travis, Houk Kendall N
Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.
Proc Natl Acad Sci U S A. 2004 Apr 20;101(16):5770-5. doi: 10.1073/pnas.0307256101. Epub 2004 Apr 12.
The catalytic asymmetric thiazolium- and triazolium-catalyzed benzoin condensations of aldehydes and ketones were studied with computational methods. Transition-state geometries were optimized by using Morokuma's IMOMO [integrated MO (molecular orbital) + MO method] variation of ONIOM (n-layered integrated molecular orbital method) with a combination of B3LYP/6-31G(d) and AM1 levels of theory, and final transition-state energies were computed with single-point B3LYP/6-31G(d) calculations. Correlations between experiment and theory were found, and the origins of stereoselection were identified. Thiazolium catalysts were predicted to be less selective then triazolium catalysts, a trend also found experimentally.
采用计算方法研究了噻唑鎓和三唑鎓催化的醛和酮的催化不对称安息香缩合反应。通过使用Morokuma的IMOMO [集成分子轨道（MO）+分子轨道方法]对ONIOM（n层集成分子轨道方法）进行变分，结合B3LYP/6-31G(d)和AM1理论水平优化过渡态几何结构，并通过单点B3LYP/6-31G(d)计算得到最终的过渡态能量。发现了实验与理论之间的相关性，并确定了立体选择性的起源。预测噻唑鎓催化剂的选择性低于三唑鎓催化剂，这一趋势在实验中也得到了证实。
