Catalytic Enantioselective Desymmetrization of Meso Compounds in Total Synthesis of Natural Products: Towards an Economy of Chiral Reagents

Abstract

Meso compounds represent a particular family of achiral molecules bearing elements of chirality. Their desymmetrization through enantioselective catalytic methods usually leads to elaborate chiral building blocks containing several stereogenic elements, which can be a very useful and elegant approach in the context of total synthesis. In the present review, the power of this strategy is illustrated through the different possibilities of catalytic enantioselective desymmetrization. From the combination of the hidden symmetry detection and the catalytic enantioselective transformations a new type of economy emerges: the economy of chiral reagents. Conclusion

Quantum formulation for nanoscale optical and material chirality: symmetry issues, space and time parity, and observables

“…The chiral product is commonly secured by selectively removing one of a pair of symmetrically disposed functional groups from the precursor, thereby removing mirror symmetry. Numerous reviews of such techniques are now available-see for example [199][200][201].…”

Metal-Catalyzed Enantioconvergent Transformations

“…Enantiocatalytic methods are key methodologies nowadays to afford the synthesis of a single enantiomer. Desymmetrization reactions have been extensively applied to achiral or meso -compounds using metal-catalyzed, organocatalyzed, and enzymatic processes. − Conversion of both enantiomers of a racemate into a single enantiomer has been carried out by dynamic kinetic resolutions (DKRs), dynamic kinetic asymmetric transformations (DyKATs), and enantioconvergent processes. − In the case of DKR, the two enantiomers undergo a reversible racemization prior to the selective reaction of one enantiomer with the chiral catalyst, whereas in the DyKATs, the equilibration of both enantiomers is due to the chiral catalyst. In type I DyKATs, both enantiomers are bounded to the catalyst, and these intermediates undergo equilibration, whereas in type II DyKATs, the racemate loses the stereocenter by interaction with the chiral catalyst to form a prochiral intermediate B·cat*.…”

Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

“…A limitation of the enzymatic resolution is that the maximum yield of the desired enantiomer is the 50% contained in the starting racemate. This is one reason for the current greater interest in enzymatic desymmetrisation reactions, in which a prochiral substrate is used [3][4][5][6][7]. The reaction generates a new chiral centre, and the enzyme shows enantiospecifity in making predominantly one enantiomer as the product.…”