Rhodium-catalyzed asymmetric hydrogenation through dynamic kinetic resolution: asymmetric synthesis of anti-β-hydroxy-α-amino acid esters
作者:Kazuishi Makino、Takefumi Fujii、Yasumasa Hamada
DOI:10.1016/j.tetasy.2006.01.040
日期:2006.2
Rhodium-catalyzed asymmetrichydrogenation of α-amino-β-keto ester hydrochlorides through dynamic kineticresolution is described. The hydrogenation proceeds with the catalyst derived from a Rh complex and a chiral ferrocenylphosphine under hydrogen in the presence of sodium acetate in acetic acid to afford anti-β-hydroxy-α-amino acid esters with 58–83% ee in a diastereomeric ratio of 92:8–97:3.
syn α-benzoylamido β-hydroxy esters through asymmetrictransferhydrogenation (ATH) with a tethered Rh(III)–DPEN complex via dynamic kinetic resolution (DKR) has been developed for the first time starting from α-benzoylamido β-keto esters. A variety of α-benzoylamido β-keto esters were converted under mild conditions into the corresponding syn α-benzoylamino β-hydroxy esters with high yields (up to 98%)
The anti selective hydrogenation of α-amino-β-keto esters via dynamickineticresolution was achieved for the first time by using the iridium−MeOBIPHEP catalyst in asymmetricsynthesis of anti aromatic β-hydroxy-α-amino acid esters with excellent diastereo- and enantioslectivities. Acetic acid as a solvent and sodium acetate as an additive affected dramatically the yield and the enantioselectivity
Diastereo‐ and Enantioselective Hydrogenation of α‐Amino‐β‐Keto Ester Hydrochlorides Catalyzed by an Iridium Complex with MeO‐BIPHEP and NaBAr
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: Catalytic Cycle and Five‐Membered Chelation Mechanism of Asymmetric Hydrogenation
Ir‐catalyzed asymmetric hydrogenation of α‐amino‐β‐keto ester hydrochlorides is described. This reaction proceeds through a dynamic kinetic resolution to produce anti‐β‐hydroxy‐α‐amino acid esters in a high diastereo‐ and enantioselective manner. Mechanistic studies have revealed that this unique asymmetric hydrogenation proceeds through reduction of the ketone moiety via the five‐membered transition state
Rhodium-Catalyzed anti and syn Enantio- and Diastereoselective Transfer Hydrogenation of α-Amino β-Keto Ester Hydrochlorides through Dynamic Kinetic Resolution
enantioselectivities (ee up to >99%). A mild catalyticasymmetrictransferhydrogenation of a series of α-amino β-keto ester hydrochlorides catalyzed by a rhodium(III) complex is reported. The use of the formic acid/triethylamine system as the hydrogen donor source provided the corresponding anti and syn amino alcohols with complete conversions, fair diastereoselectivities (up to 97:3 dr), and high enantioselectivities