With increasing demand for the use of enantiomerically pure substances as drugs we witness rapid development of synthetic protocols which are capable to provide such products efficiently, at large scale and with concern for environmental issues.

Nature is the originalnal supplier of chiral non-racemic compounds. Direct transformation of natural products, such as carbohydrates, amino and hydroxy acids and terpenes, is frequently used for drug synthesis. Less frequent appears the use of natural products as chiral auxiliaries in asymmetric syntheses whereas enantiomer separation by diastereomeric salts or complexes is still of great practical importance. However, the structural variety of natural products is quite limited so their rational use in the synthesis of structurally diverse drugs is questionable.

Chirality multiplication with the use of nature-derived pool of chiral compounds (including catalysts and biocatalysts) is a much more flexible strategy for the synthesis of enantiomerically pure products, with no limit to their structural varieties. Chirality multiplication can be achieved either by asymmetric catalysis or by deracemisation processes.

Asymmetric catalysis with chiral ligand-metal complexes has been developed in the past 25 years to such an extent that the formation of a C-C, C-O or C-N bond at the chiral center presents now no problem. These processes encompass a wide range of reactions, including asymmetric hydrogenations (AH), asymmetric epoxidations (AE), asymmetric dihydroxylations (AD), asymmetric aminohydroxylations (AAH), asymmetric aldol reactions (AA), asymmetric Diels-Alder reactions (ADA), asymmetric reductions, asymmetric alkylations, and many other. With regard to chiral catalysts, some of them have been useful for a range of applications (so called privileged chiral catalysts), and interestingly a number of them employs C₂-chiral ligands derived from either tartaric acid, trans-1,2-diaminocyclohexane or 1,1'-bi-2-naphthol.

Chiral organocatalysts are emerging now as highly competitive to chiral metal complexes. They present less environmental hazard and work under less stringent regimes. Nature derived cinchona alkaloids and amino acid proline are best known representatives of this class of chiral catalysts.

Enzyme catalysed chemical transformations are now widely recognized as practical alternatives to traditional organic synthetic methods. In many cases otherwise intractable synthetic problems can be solved by biocatalysis and its use for industrial synthesis has now become routine. Lipases, esterases, dehydrogenases, and amidases are frequently applied for carbon-heteroatom bond formation while aldolases are applied for carbon-carbon bond formation.

Both enzymes and simple chiral organic compounds can be used for kinetic resolution of racemates - a highly effective alternative compared to classical resolutions of diastereomers. Ultimately, chemically or enzymatically catalysed racemisation combined with kinetic resolution can transform a racemate into a single enantiomer - a procedure well suiteded for industrial applications.

There is no single method of chirality multiplication which can be universally applied to solve any synthetic problem. Rather, as numerous examples show, one needs to tailor chirality multiplication strategies to specific needs and requirements.

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