About Dendrimers: Structure, Physical Properties, and Applications

Hydrogenation is a core technology in chemical synthesis. High rates and selectivities are attainable only by the coordination of structurally well-designed catalysts and suitable reaction conditions. The newly devised [RuCl(2)(phosphane)(2)(1,2-diamine)] complexes are excellent precatalysts for homogeneous hydrogenation of simple ketones which lack any functionality capable of interacting with the metal center. This catalyst system allows for the preferential reduction of a C=O function over a coexisting C=C linkage in a 2-propanol solution containing an alkaline base. The hydrogenation tolerates many substituents including F, Cl, Br, I, CF(3), OCH(3), OCH(2)C(6)H(5), COOCH(CH(3))(2), NO(2), NH(2), and NRCOR as well as various electron-rich and -deficient heterocycles. Furthermore, stereoselectivity is easily controlled by the electronic and steric properties (bulkiness and chirality) of the ligands as well as the reaction conditions. Diastereoselectivities observed in the catalytic hydrogenation of cyclic and acyclic ketones with the standard triphenylphosphane/ethylenediamine combination compare well with the best conventional hydride reductions. The use of appropriate chiral diphosphanes, particularly BINAP compounds, and chiral diamines results in rapid and productive asymmetric hydrogenation of a range of aromatic and heteroaromatic ketones and gives a consistently high enantioselectivity. Certain amino and alkoxy ketones can be used as substrates. Cyclic and acyclic alpha,beta-unsaturated ketones can be converted into chiral allyl alcohols of high enantiomeric purity. Hydrogenation of configurationally labile ketones allows for the dynamic kinetic discrimination of diastereomers, epimers, and enantiomers. This new method shows promise in the practical synthesis of a wide variety of chiral alcohols from achiral and chiral ketone substrates. Its versatility is manifested by the asymmetric synthesis of some biologically significant chiral compounds. The high rate and carbonyl selectivity are based on nonclassical metal-ligand bifunctional catalysis involving an 18-electron amino ruthenium hydride complex and a 16-electron amido ruthenium species.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/1521-3773%2820010105%2940%3A1%3C40%3A%3AAID-ANIE40%3E3.0.CO%3B2-5

Asymmetric Catalysis by Architectural and Functional Molecular Engineering: Practical Chemo‐ and Stereoselective Hydrogenation of Ketones

Recent Advances in the Baylis−Hillman Reaction and Applications

1,2-Amino Alcohols and Their Heterocyclic Derivatives as Chiral Auxiliaries in Asymmetric Synthesis

Large-scale applications of transition metal-catalyzed couplings for the synthesis of pharmaceuticals.

Extrem hohe Enantioselektivitat (>99.5 % ee) und chemische Ausbeute (>99 %) wurden in einer asymmetrischen autokatalytischen Reaktion erzielt. Ein (5-Pyrimidyl)alkanol mit einer tert-Butylethinylgruppe an der 2-Position (1) fungiert in der enantioselektiven Alkylierung [Gl. (1)] als sehr effizienter asymmetrischer Autokatalysator.

Eine nahezu ideale asymmetrische autokatalyse mit (2-alkinyl-5-pyrimidyl)alkanolen

(1S, 2R)-N-Benzyl-N-methylephedrinium halides in the solid state revealed much higher enantioselectivities than those in solution during the enantioselective addition of diethylzinc to aldehydes.

Chiral quaternary ammonium salts as solid state catalysts for the enantioselective addition of diethylzinc to aldehydes

Achiral ethylenediamine forms chiral structures spontaneously when crystallized as the sulfate salt. By using these chiral crystals of ethylenediamine sulfate (ethylenediammonium sulfate), asymmetr...

Asymmetric Autocatalysis Triggered by Chiral Crystal of Achiral Ethylenediamine Sulfate

In the presence of various chiral secondary alcohols as chiral initiators, an enantioselective alkylation of a pyrimidine-5-carbaldehyde using diisopropylzinc was examined: a pyrimidyl alkanol was obtained in high yield and enantiomeric excess. The correlation between the absolute configuration of the chiral secondary alcohols and the pyrimidyl alkanol is discussed.

Chiral secondary alcohol-induced asymmetric autocatalysis: correlation between the absolute configuration of the chiral initiators and the product

Solvent-free enantioselective addition of dialkylzincs to N-diphenylphosphinoylimines in the presence of chiral 2-morpholino-1-phenylpropan-1-ol affords N-diphenylphosphinoylamines with up to 97% ee. The reaction in the solvent-free system is faster than in organic solvents.

Kenso Soai

Papers

Eine nahezu ideale asymmetrische autokatalyse mit (2-alkinyl-5-pyrimidyl)alkanolen

Chiral quaternary ammonium salts as solid state catalysts for the enantioselective addition of diethylzinc to aldehydes

Asymmetric Autocatalysis Triggered by Chiral Crystal of Achiral Ethylenediamine Sulfate

Chiral secondary alcohol-induced asymmetric autocatalysis: correlation between the absolute configuration of the chiral initiators and the product

Asymmetric synthesis of N-diphenylphosphinoylamines by solvent-free enantioselective addition of dialkylzincs to N-diphenylphosphinoylimines