Chemo- and Enantioselective Brønsted Acid-Catalyzed Reduction of α-Imino Esters with Catecholborane
作者:Dieter Enders、Andreas Rembiak、Bianca Anne Stöckel
DOI:10.1002/adsc.201300352
日期:2013.7.8
The chemo‐ and enantioselectivereduction of α‐imino esters with catecholborane has been developed employing 10 mol% of an enantiopure BINOL‐based phosphoric acid as organocatalyst. Various differently substituted aromatic α‐amino acid derivatives can be achieved in almost quantitative yields and very good to excellent enantioselectivities of up to 96% ee under mild reaction conditions.
In order to develop an efficient organocatalyst for the enantioselective N-H insertion reaction via carbene/carbenoid, the catalytic core of the cinchonaalkaloids was investigated. According to our working hypothesis of an eight-membered ring transition state in the N-H insertion reaction, two pairs of enantiomers related to 2-amino-1-phenylethanol were investigated for their chiral inducing potential
Modular construction of multifunctional ligands for the enantioselective ruthenium-catalyzed carbenoid N–H insertion reaction: an enzyme-like and substrate-sensitive catalyst system
It was found for the first time that BINOL-derived multifunctional ligands bearing a silicon-based bulky group exhibited promising enantioselective control in the ruthenium-catalysed carbenoid N–H insertion reaction.
Ammonium ylides generated in situ from phenyldiazoacetates and anilines undergo asymmetric N−H insertionreactions catalyzed by cinchona alkaloids (1 mol %), affording phenylglycines up to 74% ee.
Asymmetric Intermolecular N-H Insertion Reaction of Phenyldiazoacetates with Anilines Catalyzed by Achiral Dirhodium(II) Carboxylates and Cinchona Alkaloids
Asymmetric N-H insertion of phenyldiazoacetates with anilines catalyzed cooperatively by achiral dirhodium(II) carboxylates and cinchona alkaloids is described. A new catalytic system of dirhodium(II) tetrakis(triphenylacetate), Rh(2)(TPA)(4), and dihydrocinchonine provides phenylglycine derivatives in up to 71% ee.