Catalytic asymmetric direct aldol reactions of arylketones and arylaldehydes or reactive arylketones
نویسندگان
چکیده
منابع مشابه
Organocatalytic direct asymmetric aldol reactions in water.
We have developed direct asymmetric cross-aldol reactions that can be performed in water without addition of organic solvents. A bifunctional catalyst with a long hydrophobic alkyl chain efficiently catalyzed the reactions and afforded the desired aldol products in excellent yield with high enantiomeric excess, even when only an equal molar ratio of the donor and acceptor was used. These result...
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Direct asymmetric catalytic aldol reactions have been successfully performed using aldehydes and unmodified ketones together with commercially available chiral cyclic secondary amines as catalysts. Structure-based catalyst screening identified L-proline and 5,5-dimethyl thiazolidinium-4-carboxylate (DMTC) as the most powerful amino acid catalysts for the reaction of both acyclic and cyclic keto...
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Thioamides are the preferred pronucleophiles for direct catalytic asymmetric aldol reactions in the context of soft Lewis acid/hard Brønsted base cooperative catalysis. In-depth investigation of this proton-transfer catalysis, which is virtually in equilibrium, revealed that the prominence of the retro-aldol reaction depended on the substrate combination. The retro-aldol reaction is a serious i...
متن کاملDirect asymmetric aldol reactions catalyzed by lipase from porcine pancreas.
Porcine pancreas lipase type II (PPL II) exhibited unnatural catalytic activity in direct asymmetric aldol reactions between cyclic ketones and aromatic or heteroaromatic aldehydes in acetonitrile in the presence of phosphate buffer. A wide range of substrates was accepted by the enzyme to afford the corresponding aldol products in low to high yields (10-98%), with moderate to excellent enantio...
متن کاملEnamine-based organocatalysis with proline and diamines: the development of direct catalytic asymmetric Aldol, Mannich, Michael, and Diels-alder reactions.
Enamines and imines have long been recognized as key intermediates in enzyme catalysis, particularly within a class of enzymes organic chemists would very much like to emulate, the aldolases. Here we summarize the contributions of this laboratory to converting enzymatic enamines, and in some cases imines, into a versatile catalytic asymmetric strategy powered by small organic molecules.
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ژورنال
عنوان ژورنال: SCIENTIA SINICA Vitae
سال: 2017
ISSN: 1674-7232
DOI: 10.1360/n052017-00009