Practical and Highly Selective Sulfur Ylide-Mediated Asymmetric Epoxidations and Aziridinations Using a Cheap and Readily Available Chiral Sulfide: Extensive Studies To Map Out Scope, Limitations, and Rationalization of Diastereo- and Enantioselectivities
作者:Ona Illa、Mariam Namutebi、Chandreyee Saha、Mehrnoosh Ostovar、C. Chun Chen、Mairi F. Haddow、Sophie Nocquet-Thibault、Matteo Lusi、Eoghan M. McGarrigle、Varinder K. Aggarwal
DOI:10.1021/ja405073w
日期:2013.8.14
The chiral sulfide, isothiocineole, has been synthesized in one step from elemental sulfur, γ-terpinene, and limonene in 61% yield. A mechanism involving radical intermediates for this reaction is proposed based on experimental evidence. The application of isothiocineole to the asymmetric epoxidation of aldehydes and the aziridination of imines is described. Excellent enantioselectivities and diastereoselectivities
手性硫化物异硫辛醇由元素硫、γ-萜品烯和柠檬烯一步合成,产率为 61%。基于实验证据提出了涉及该反应的自由基中间体的机制。描述了异硫辛醇在醛的不对称环氧化和亚胺的氮丙啶化中的应用。使用简单的实验方案已在广泛的芳香族、脂肪族和 α,β-不饱和醛中获得了出色的对映选择性和非对映选择性。在氮丙啶化反应中,对多种亚胺都具有优异的对映选择性和良好的非对映选择性。已经提出了机械模型来合理化观察到的高选择性,这应该使硫化物能够在合成中充满信心地使用。在环氧化中,甜菜碱形成的可逆程度决定了非对映选择性和对映选择性。在了解反应机理的基础上适当调整反应条件可以在大多数情况下获得高选择性。在氮丙啶化反应中,甜菜碱的形成与半稳定的叶立德是不可逆的,非对映选择性在甜菜碱形成步骤中确定,因此变化更大。