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Enantioselective synthesis, also called asymmetric synthesis, [1] is a form of chemical synthesis. It is defined by IUPAC as "a chemical reaction (or reaction sequence) in which one or more new elements of chirality are formed in a substrate molecule and which produces the stereoisomeric ( enantiomeric or diastereomeric ) products in unequal ...
Asymmetric epoxidation is often feasible. [4] One named reaction is the Jacobsen epoxidation, which uses manganese-salen complex as a chiral catalyst and NaOCl as the oxidant. The Sharpless epoxidation using chiral N-heterocyclic ligands and osmium tetroxide. Instead of asymmetric epoxidation, alkenes are susceptible to asymmetric dihydroxylation.
Asymmetric hydrogenation is a chemical reaction that adds two atoms of hydrogen to a target (substrate) molecule with three-dimensional spatial selectivity.Critically, this selectivity does not come from the target molecule itself, but from other reagents or catalysts present in the reaction.
Asymmetric counteranion directed catalysis (ACDC) [1] or chiral anion catalysis [2] in enantioselective synthesis is the "induction of enantioselectivity in a reaction proceeding through a cationic intermediate by means of ion pairing with a chiral, enantiomerically pure anion provided by the catalyst". [1]
Furthermore, the catalytic and organometallic studies on Wilkinson's catalyst also played a significant role on the subsequent development of cationic Rh- and Ru-based asymmetric hydrogenation transfer catalysts which set the foundations for modern asymmetric catalysis. [6]
In one type of catalysis ion-pairing exists with a charged and chiral catalyst. The charged catalyst can be cationic or anionic. Catalysis by anionic catalysts is also called asymmetric counteranion-directed catalysis. In the other variation of asymmetric ion-pairing catalysis called anion or cation binding, the chiral catalyst is neutral but ...
Ligands containing atomic chirality centers such asymmetric carbon, which usually do not have C 2-symmetry, remain important in catalysis. Examples include cinchona alkaloids and certain phosphoramidites. P-chiral monophosphines have also been investigated.
When the organocatalyst is chiral an avenue is opened to asymmetric catalysis; for example, the use of proline in aldol reactions is an example of chirality and green chemistry. [10] Organic chemists David MacMillan and Benjamin List were both awarded the 2021 Nobel Prize in chemistry for their work on asymmetric organocatalysis. [11]