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Squaramide Catalysis
Within the area of organocatalysis, squaramide catalysis describes the use of squaramides to accelerate and stereochemically alter organic transformations. The effects arise through hydrogen-bonding interactions between the substrate and the squaramide, unlike classic catalysts, and is thus a type of Hydrogen-bond catalysis, hydrogen-bond catalyst. The scope of these small-molecule H-bond donors termed squaramide organocatalysis covers both non-stereoselective and stereoselective applications. Structure A squaramide organocatalyst typically contains the squaramide group and a Hydrogen bond, hydrogen bond donor which is usually a Amine, tertiary amine group. The 3,5-bis(trifluoromethyl)phenyl-group is commonly used for the R group. For Enantioselective synthesis, enantioselective squaramide catalysis, chirality is induced via the tertiary amine group. There are cases where both sides of the squaramide are tertiary amines. Catalyst-substrate interactions The interaction between t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organocatalysis
In organic chemistry, organocatalysis is a form of catalysis in which the rate of a chemical reaction is increased by an organic catalyst. This "organocatalyst" consists of carbon, hydrogen, sulfur and other nonmetal elements found in organic compounds.Special Issue: Because of their similarity in composition and description, they are often mistaken as a misnomer for enzymes due to their comparable effects on reaction rates and forms of catalysis involved. Organocatalysts which display secondary amine functionality can be described as performing either enamine catalysis (by forming catalytic quantities of an active enamine nucleophile) or iminium catalysis (by forming catalytic quantities of an activated iminium electrophile). This mechanism is typical for covalent organocatalysis. Covalent binding of substrate normally requires high catalyst loading (for proline-catalysis typically 20–30 mol%). Noncovalent interactions such as hydrogen-bonding facilitates low catalyst loa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
