Modular chiral dendritic monodentate phosphoramidite ligands for Rh(II)-catalyzed asymmetric hydrogenation: unprecedented enhancement of enantioselectivity.
نویسندگان
چکیده
Modular chiral dendrimers with monodentate phosphoramidite ligands located at the core were synthesized and applied in the Rh-catalyzed asymmetric hydrogenations, afforded unprecedented enhancement of enantioselectivity.
منابع مشابه
Monodentate chiral spiro phosphoramidites: efficient ligands for rhodium-catalyzed enantioselective hydrogenation of enamides.
Optically active -arylalkylamines are an important class of compounds that are widely used in organic and pharmaceutical synthesis, and much effort has been made to develop efficient asymmetric synthetic methods for them.[1] Asymmetric catalytic hydrogenation of enamides, initiated by Kagan et al. ,[2] provides a direct and convenient route to chiral amine derivatives. However, many well-known ...
متن کاملAsymmetric hydrogenation using monodentate phosphoramidite ligands.
Monodentate phosphoramidites are excellent ligands for Rh-catalyzed asymmetric hydrogenations of substituted olefins. Enantioselectivities between 95 and 99% were obtained in the asymmetric hydrogenation of protected alpha- and beta-dehydroamino acids and esters, itaconic acid and esters, aromatic enamides, aromatic enol esters, aromatic and aliphatic enol carbamates, and alpha-substituted cinn...
متن کاملPipPhos and MorfPhos: privileged monodentate phosphoramidite ligands for rhodium-catalyzed asymmetric hydrogenation.
A library of 20 monodentate phosphoramidite ligands has been prepared and applied in rhodium-catalyzed asymmetric hydrogenation. This resulted in the identification of two ligands, PipPhos and MorfPhos, that afford excellent and in several cases unprecedented enantioselectivities in the hydrogenation of N-acyldehydroamino acid esters, dimethyl itaconate, acyclic N-acylenamides, and cyclic N-acy...
متن کاملReaction Kinetics and Mechanistic Studies of the Rh-Catalyzed Asymmetric Hydrogenation with MonoPhosTM
In this chapter the results of kinetic studies of the rhodium-catalyzed asymmetric hydrogenation using monodentate phosphoramidite ligands are described. Together with the data obtained by a number of other techniques a mechanism for the Rhcatalyzed asymmetric hydrogenation with MonoPhosTM is proposed. The formation of the catalyst precursor results in a mixture of diastereomeric Rh-complexes w...
متن کاملAsymmetric hydrogenation of α- or β-acyloxy α,β-unsaturated phosphonates catalyzed by a Rh(I) complex of monodentate phosphoramidite.
The Rh(I) complex of a monodentate phosphoramidite bearing a primary amine moiety (DpenPhos) has been disclosed to be highly efficient for the asymmetric hydrogenation of a variety of α- or β-acyloxy α,β-unsaturated phosphonates, providing the corresponding biologically important chiral α- or β-hydroxy phosphonic acid derivatives with excellent enantioselectivities (90->99% ee).
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ورودعنوان ژورنال:
- Chemical communications
دوره 45 شماره
صفحات -
تاریخ انتشار 2008