Enantioselective Olefin Epoxidation using Axially Chiral Biaryl Azepinium Salts as Catalysts. Rapidin-situ Screening and Origin of the Stereocontrol
作者:Roman Novikov、Gérald Bernardinelli、Jérôme Lacour
DOI:10.1002/adsc.200800022
日期:2008.5.5
stereocontrol in epoxidation reactions of unfunctionalized alkenes by diastereomeric biaryl oxaziridinium salts, two series of novel iminium cations were prepared. These moieties combine (Ra)-dimethylbiphenyl or (Ra)-5,5′,6,6′,7,7′,8,8′-octahydrobinaphthyl cores with chiral exocyclic appendages derived from commercially available (S)- or (R)-3,3-dimethylbutan-2-amine and (S)- or (R)-1-phenylpropan-1-amine
为了揭示立体异构控制在非功能化烯烃通过非对映体联芳基恶二叠氮鎓盐的环氧化反应中的起源,制备了两个系列的新型亚胺阳离子。这些部分将(R a)-二甲基联苯或(R a)-5,5',6,6',7,7',8,8'-八氢联萘核心与衍生自商业上可获得的(S)-或(R)-3,3-二甲基丁-2-胺和(S)-或(R)-1-苯基丙-1-胺。在双相对映选择性烯烃环氧化条件下,原位这些衍生物生成的溴化物盐显示出与经典联萘衍生物相似或更好的不对称效率。进行结构分析以寻找产物中立体控制的起点/对映选择性水平与催化剂的联芳基捻度周围的二面角之间的相关性。