Asymmetric hydrogenation of α-keto acid derivatives by rhodium-}amidophosphine-phosphinite{ catalysts
摘要:
The enantioselective hydrogenation of several alpha-keto esters (3a-f, 5a-j), alpha-keto amides (7a-e) and isatine derivatives (9a-d) with a set of four representative neutral homogeneous rhodium-amidophosphine-phosphinite catalysts has been investigated. Trifluoroacetato-Rh-AMPP catalytic precursors promoted the rapid, efficient synthesis of aliphatic oc-hydroxy esters 4a-f in moderate to high enantioselectivities (66-95% ee), in contrast to most aromatic alpha-hydroxy esters 6a-j (8-81% ee). Best enantioselectivities for alpha-hydroxy amides 8a-e (85-95% ee) and dioxindoles 10a-d (80-94% ee) were obtained with chloro-Rh-AMPP precursors. It is proposed that, contrary to alpha-keto amides, alpha-keto esters do not chelate onto the rhodium center and that, in such circumstances, the asymmetric induction is mainly controlled by the steric hindrance around the C=O function. (C) 1997 Elsevier Science Ltd.
Abstract Aminocarbonylation of aryliodides with aromatic and aliphatic amines, leading to formation of the corresponding amides, was efficiently carried out in water under 1 atm of CO usingpalladiumnanoparticles (Pd NPs) formed in situ from [PdCl2(Ar2-BIAN)] complexes. The role of Ar2-BIAN ligands in the stabilization of Pd NPs was evidenced. The nature of the catalytically active species was confirmed
Asymmetric Aerobic Oxidation of α-Hydroxy Acid Derivatives Catalyzed by Reusable, Polystyrene-Supported Chiral N-Salicylidene Oxidovanadium tert-Leucinates
作者:Santosh B. Salunke、N.Seshu Babu、Chien-Tien Chen
DOI:10.1002/adsc.201100062
日期:2011.5
The direct immobilization of two different C‐5‐propargyl ether‐modified, chiral N‐salicylidene vanadyl(V) tert‐leucinates onto 4‐azidomethyl‐substituted polystyrene by clickchemistry was examined. Among the eight different solvents investigated, the resulting polystyrene‐supported catalysts promote the asymmetric, aerobic oxidation of α‐hydroxy (thio)esters and amides with enantioselectivities of
Selective amidation by a photocatalyzed umpolung reaction
作者:Debasish Ghosh、Rajesh Nandi、Saikat Khamarui、Sukla Ghosh、Dilip K. Maiti
DOI:10.1039/c9cc01079c
日期:——
Herein, a metal-catalyzed organic transformation merged with another organophotocatalyst has been developed under mild conditions for the production of α-ketoamides.
在此,已经开发了一种金属催化的有机转化,与另一种有机光催化剂在温和条件下结合,用于生产α-酮酰胺。
Enantioselective Iridium-Catalyzed Hydrogenation of α-Keto Amides to α-Hydroxy Amides
A highly enantioselective iridium-catalyzed hydrogenation of α-keto amides to form α-hydroxy amides has been achieved with excellent results (up to >99% conversion and up to >99% ee, TON up to 100 000). As an example, this protocol was applied to the synthesis of (S)-4-(2-amino-1-hydroxyethyl)benzene-1,2-diol, the enantiomer of norepinephrine, which is widely used as an injectable drug for the treatment