Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States.
J Am Chem Soc. 2012 Sep 26;134(38):16054-8. doi: 10.1021/ja3075538. Epub 2012 Sep 18.
Stereoselectivities of the dihydroxylations of cis-bicyclo[3.3.0]octene intermediates for a projected total synthesis of chromodorolide A have been explored experimentally. The reaction occurs unexpectedly on the apparently more hindered (concave) face; this result has been explained through computational studies using B3LYP and B3LYP-D3 methods. Torsional effects are largely responsible for the stereoselectivity encountered in the chromodorolide A synthesis. Many literature examples have been reported on related cases. QM calculations show that the stereoselectivities of dihydroxylations of fused cyclopentenes are influenced by the conformational rigidity or flexibility of the substrate. Torsional, electrostatic, and steric effects can all influence stereoselectivity, and the rigidity or flexibility of conformations of reactants provides a predictive guide to stereoselectivity.
为了预测色多醇 A 的全合成，我们实验探索了顺式双环[3.3.0]辛烯中间体的双羟化的立体选择性。反应出人意料地发生在明显受阻（凹面）的面上；这一结果通过 B3LYP 和 B3LYP-D3 方法的计算研究得到了解释。扭转效应是色多醇 A 合成中遇到的立体选择性的主要原因。文献中已经报道了许多相关案例。QM 计算表明，稠合环戊烯的双羟化的立体选择性受底物构象刚性或柔性的影响。扭转、静电和空间位阻效应都可以影响立体选择性，反应物构象的刚性或柔性为立体选择性提供了预测性指导。
