Light-Induced Enantioselective Hydrogenation Using Chiral Derivatives of Casey’s Iron–Cyclopentadienone Catalyst
作者:Albrecht Berkessel、Sebastian Reichau、Adrian von der Höh、Nicolas Leconte、Jörg-M. Neudörfl
DOI:10.1021/om200459s
日期:2011.7.25
reaction could be avoided. Instead, the catalytic cycle is accessed from air-stable carbonyl precursors. In the hydridic form of the phosphoramidite–carbonyl catalysts, the iron atom itself becomes a stereocenter. NMR spectroscopy confirmed the generation of two hydride diastereomers. With the MonoPhos iron dicarbonyl complex, moderate enantioselectivity (up to 31% ee) was achieved in the hydrogenation of
我们在此报告了使用均相铁(II)-环戊二烯酮-三羰基体系的手性改性衍生物(称为Casey催化剂)进行不对称酮氢化的第一个例子。为了合成手性改性催化剂,将三个羰基配体之一交换为手性亚磷酰胺。为此,应用使用三甲胺-N-氧化物的氧化脱羰或光解。还使用光解作用将三羰基铁预催化剂(以及类似地,二羰基亚磷酰胺络合物)转化为配位不饱和的二羰基(分别为单羰基)络合物,它们是酮加氢催化循环中的中间体。后一种物质的氢吸收提供了“负载”的氢化物,如1所示。1 H NMR光谱。因此,可以避免通过通常低产率的希伯反应制备敏感的氢化铁。相反,从空气稳定的羰基前体进入催化循环。在亚磷酰胺-羰基催化剂的氢化形式中,铁原子本身成为立体中心。NMR光谱证实了两种氢化物非对映异构体的产生。使用MonoPhos二羰基铁络合物,在苯乙酮的氢化过程中实现了中等对映选择性(高达31%ee)。
A highly stereoselective catalytic alkylation sequence for the synthesis of highly functionalized and versatile five-membered-ring compounds bearing all-carbon quaternary stereocenters was developed. Enantioselective desymmetrization of achiral cyclopentene-1,3-diones was thus executed by chiral Cu-phosphoramidite catalysts. A variety of complicated cyclopentane derivatives can be synthesized with
Chiral phosphite-urea bifunctional catalysts have been developed for the enantioselective bromocyclization of 2-geranylphenols with N-bromophthalimide (NBP) for the first time.