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These catalysts and reactions have a long history but current interest in organocatalysis is focused on asymmetric catalysis with chiral catalysts, called asymmetric organocatalysis or enantioselective organocatalysis. A pioneering reaction developed in the 1970s is called the Hajos–Parrish–Eder–Sauer–Wiechert reaction. Between 1968 and ...
Hydrogen-bond catalysis is a type of organocatalysis that relies on use of hydrogen bonding interactions to accelerate and control organic reactions. In biological systems, hydrogen bonding plays a key role in many enzymatic reactions, both in orienting the substrate molecules and lowering barriers to reaction. [1]
Schreiner's thiourea, N,N'-bis3,5-bis(trifluormethyl)phenyl thiourea, combines all structural features for double H-bonding mediated organocatalysis: electron-poor; rigid structure; non-coordinating, electron withdrawing substituents in 3,4, and/or 5 position of a phenyl ring; the 3,5-bis(trifluoromethyl)phenyl-group is the preferred substituent
The discipline organocatalysis is divided into the application of covalent (e.g., proline, DMAP) and non-covalent (e.g., thiourea organocatalysis) organocatalysts referring to the preferred catalyst-substrate binding and interaction, respectively. The Nobel Prize in Chemistry 2021 was awarded jointly to Benjamin List and David W.C. MacMillan ...
Proline organocatalysis is the use of proline as an organocatalyst in organic chemistry. This theme is often considered the starting point for the area of organocatalysis, even though early discoveries went unappreciated. [1] Modifications, such as MacMillan’s catalyst and Jorgensen's catalysts, proceed with excellent stereocontrol. [2]: 5574 [3]
Using chiral ammonium cations can give high enantioselectivity of the alpha-etherification reaction, an example of an efficient chiral metal-free organocatalysis process. [ 5 ] [ 6 ] Several guanidinium hypoiodites can also be used in the various oxidative-coupling reactions.
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 catalyst.
Thioureas have a trigonal planar molecular geometry of the N 2 C=S core. The C=S bond distance is near 1.71 Å, which is 0.1 Å longer than in normal ketones (R 2 C=O).The C–N bond distances are short. [1]