Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland.
Science. 2013 May 31;340(6136):1065-8. doi: 10.1126/science.1237068.
An important challenge in asymmetric synthesis is the development of fully stereodivergent strategies to access the full complement of stereoisomers of products bearing multiple stereocenters. In the ideal case, where four products are possible, applying distinct catalysts to the same set of starting materials under identical conditions would in a single step afford any given stereoisomer. Herein, we describe the realization of this concept in a fully stereodivergent dual-catalytic synthesis of γ,δ-unsaturated aldehydes bearing vicinal quaternary/tertiary stereogenic centers. The reaction is enabled by chiral iridium and amine catalysts, which activate the allylic alcohol and aldehyde substrates, respectively. Each catalyst exerts high local stereocontrol irrespective of the other's inherent preference.
在手性合成中，一个重要的挑战是开发完全立体发散的策略，以获得具有多个立体中心的产物的所有立体异构体。在理想情况下，当有四个产物可能时，在相同条件下将不同的催化剂应用于同一组起始原料，将在单个步骤中提供任何给定的立体异构体。在这里，我们描述了在带有相邻季碳/叔碳立体手性中心的γ,δ-不饱和醛的完全立体发散的双催化合成中实现这一概念。该反应由手性铱和胺催化剂激活，分别激活烯丙醇和醛底物。每个催化剂都发挥了高的局部立体控制作用，而不受其他催化剂固有偏好的影响。
