PipPhos and MorfPhos: privileged monodentate phosphoramidite ligands for rhodium-catalyzed asymmetric hydrogenation.
نویسندگان
چکیده
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-acylenamides. In addition, a method for the parallel enantioselectivity determination of eight acylated amines is presented.
منابع مشابه
Asymmetric Hydrogenation of Quinolines Catalyzed by Iridium Complexes of Monodentate BINOL-Derived Phosphoramidites
The monodentate BINOL-derived phosphoramidite PipPhos is used as ligand for the iridium-catalyzed asymmetric hydrogenation of 2and 2,6-substituted quinolines. If tri-ortho-tolylphosphine and/or chloride salts are used as additives enantioselectivities are strongly enhanced up to 89%. NMR indicates that no mixed complexes are formed upon addition of tri-ortho-tolylphosphine.
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[reaction: see text] Monodentate phosphoramidites, in particular PipPhos and its octahydro analogue, are excellent ligands for the rhodium-catalyzed asymmetric hydrogenation of aromatic enol acetates, enol carbamates, and 2-dienol carbamates up to 98% ee. These latter substrates were hydrogenated selectively to the carbamates of the allyl alcohol.
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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 کاملMonodentate, Supramolecular and Dynamic Phosphoramidite Ligands Based on Amino Acids in Asymmetric Hydrogenation Reactions Breuil, P.A.R
The electronic and steric effects as well as hydrogen bonds on the formation of the heteroligand complexes between monodentate amino acid based phosphoramidite and monodentate phosphine ligands were studied. Pure heterocomplex formation through the hydrogen bond between LEUPhos and a urea based phosphine is observed leading to highly active and selective catalyst. Substrate orientation through ...
متن کاملSynthesis of new monodentate spiro phosphoramidite ligand and its application in Rh-catalyzed asymmetric hydrogenation reactions.
[reaction: see text] A new spirocyclic diol, 9,9'-spirobixanthene-1,1'-diol, was synthesized in two steps from readily available starting material m-phenoxyanisole. Resolution of the racemic diol was achieved by cocrystallization with N-benzylcinchonidinium chloride and N-benzylquininium chloride in acetonitrile. The corresponding spiro monodentate phosphoramidite ligand has been prepared for R...
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ورودعنوان ژورنال:
- The Journal of organic chemistry
دوره 70 3 شماره
صفحات -
تاریخ انتشار 2005