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General stereoretentive preparation of chiral secondary mixed alkylmagnesium reagents and their use for enantioselective electrophilic aminations
Chemical Science ( IF 7.6 ) Pub Date : 2021-10-19 , DOI: 10.1039/d1sc05315a
Alexander Kremsmair 1 , Henrik R Wilke 1 , Matthias M Simon 1 , Quirin Schmidt 1 , Konstantin Karaghiosoff 1 , Paul Knochel 1
Affiliation  

A general preparation of enantiomerically and diastereomerically enriched secondary alkylmagnesium reagents was reported as well as their use for performing highly stereoselective transition-metal free electrophilic aminations leading to α-chiral amines in up to 97% ee. Thus, the reaction of t-BuLi (2.2 equiv.) with a mixture of chiral secondary alkyl iodides and the commercially available magnesium reagent Me3SiCH2MgCl in a 2 : 1 mixture of pentane and diethyl ether at up to −50 °C provided optically enriched secondary mixed alkylmagnesium species of the type alkyl(Me)CHMgCH2SiMe3 with high retention of configuration (up to 99% ee). The resulting enantiomerically enriched dialkylmagnesium reagents were trapped with electrophiles such as non-enolizable ketones, aldehydes, acid chlorides, isocyanates, chlorophosphines and O-benzoyl hydroxylamines providing α-chiral tertiary alcohols, ketones, amides, phosphines and tertiary amines in up to 89% yield (over three reaction steps) and up to 99% ee.

中文翻译:


手性二级混合烷基镁试剂的通用立体保留制备及其在对映选择性亲电胺化中的应用



报道了对映体和非对映体富集的仲烷基镁试剂的一般制备方法,以及它们在进行高度立体选择性的无过渡金属亲电胺化中的用途,从而产生高达 97% ee 的 α-手性胺。因此, t -BuLi(2.2当量)与手性仲烷基碘和市售镁试剂Me 3 SiCH 2 MgCl的混合物在戊烷和乙醚的2:1混合物中在高达-50°C下反应提供了烷基(Me)CHMgCH 2 SiMe 3类型的光学富集的二次混合烷基镁物质,具有高构型保留率(高达 99% ee)。所得对映体富集的二烷基镁试剂被诸如不可烯醇化的酮、醛、酰氯、异氰酸酯、氯膦和O-苯甲酰羟胺等亲电试剂捕获,提供高达89%的α-手性叔醇、酮、酰胺、膦和叔胺产率(超过三个反应步骤)和高达 99% ee。
更新日期:2021-10-26
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