Highly Enantioselective Hydrogenation of Enol Ester Phosphonates: A Versatile Procedure for the Preparation of Chiral beta-Hydroxyphosphonates (original) (raw)

New chiral phosphine–phosphites: a convenient synthesis based on the demethylation of o-anisyl phosphines and application in highly enantioselective catalytic hydrogenations

Tetrahedron-asymmetry, 2001

An easy demethylation of o-anisyl phosphines provides a convenient access to a series of new chiral phosphine–phosphites. The screening of these derivatives as ligands in rhodium-catalyzed asymmetric hydrogenation of dimethyl itaconate has shown a profound influence of ligand structure on the enantioselectivity of the process.Graphic2-(Diphenylphosphino)phenyl-(S)-3,3′-di-tert-butyl-5,5′,6,6′-tetramethyl-1,1′-biphen-2,2′-diyl-phosphiteC42H46O3P2Ee=100%[α]D20=406 (c 1.0, THF)Source of chirality: (S)-3,3′-di-tert-butyl-5,5′,6,6′-tetramethyl-1,1′-biphenyl-2,2′-diol2-(Dimethylphosphino)phenyl-(S)-3,3′-di-tert-butyl-5,5′,6,6′-tetramethyl-1,1′-biphen-2,2′-diyl-phosphiteC32H42O3P2Ee=100%[α]D20=347 (c 1.0, THF)Source of chirality: (S)-3,3′-di-tert-butyl-5,5′,6,6′-tetramethyl-1,1′-biphenyl-2,2′-diol2-(Diisopropylphosphino)phenyl-(S)-3,3′-di-tert-butyl-5,5′,6,6′-tetramethyl-1,1′-biphen-2,2′-diyl-phosphiteC36H50O3P2Ee=100%[α]D20=336 (c 1.0, THF)Source of chirality: (S)-3,3′-di-tert-butyl-5,5′,6,6′-tetramethyl-1,1′-biphenyl-2,2′-diol(S)-2-(Methylphenylphosphino)phenyl-3,3′,5,5′-tetra-tert-butyl-1,1′-biphen-2,2′-diyl-phosphiteC41H52O3P2Ee=100%[α]D20=1.6 (c 1.0, THF)Source of chirality: (S)-o-anisylmethylphenylphosphine

Phenol-derived chiral phosphine–phosphite ligands in the rhodium-catalyzed enantioselective hydrogenation of functionalized olefins

Tetrahedron: Asymmetry, 2010

A set of 15 chiral Taddol-and Binol-based phosphine-phosphite ligands were tested in the Rh-catalyzed asymmetric hydrogenation of three olefins, methyl 2-hydroxymethyl-acrylate, 1-phenylvinyl acetate, and a-methyl cinnamic acid. The best enantioselectivities (up to 92% ee) were observed in the hydrogenation of methyl 2-hydroxymethyl-acrylate using Binol-based ligands. As previously observed in other applications of this class of modular chiral ligand in enantioselective catalysis, the stereochemical outcome of the reactions greatly depended on the substituents at the ligand aryl backbone in the orthoposition to the chiral phosphite unit.

Asymmetric Catalysis Special Feature Part II: Remarkably diastereoselective synthesis of a chiral biphenyl diphosphine ligand and its application in asymmetric hydrogenation

Proceedings of the National Academy of Sciences, 2004

Essentially complete atropdiastereoselectivity was realized in the preparation of biaryl diphosphine dioxide by asymmetric intramolecular Ullmann coupling and oxidative coupling with central-toaxial chirality transfer. A bridged C2-symmetric biphenyl phosphine ligand possessing additional chiral centers on the linking unit of the biphenyl groups was synthesized. No resolution step was required for the preparation of the enantiomerically pure chiral ligand. These findings offer a general and practical tool for the development of previously uninvestigated atropdiastereomeric biaryl phosphine ligands. The diphosphine ligand was found to be highly effective in the asymmetric hydrogenation of ␣and ␤ketoesters, 2-(6-methoxy-2-naphthyl)propenoic acid, ␤-(acylamino)acrylates, and enol acetates.