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Enzyme Mediated Asymmetric Synthesis
"Kinetic Resolution and Chemoenzymatic Dynamic Kinetic Resolution of
-Hydroxy Amides"
Prepared by:Lee Siang Hua (HT033441Y)
Prepared for: Assoc. Prof. Marc Garland
Date of submission: 13 April 2005
Dept. of Chemical & Biomolecular Engineering,
National University of Singapore,
10, Kent Ridge Crescent, Singapore 119260


The asymmetric synthesis of optically active compounds can be achieved in several ways, 1) resolution
of racemates 2) synthesis from the "chiral pool" 3) asymmetric induction using stoichiometric quantity of
chiral reagent 4) asymmetric chemical catalysis 5) enzyme-mediated processes. For asymmetric synthesis
the most important enzymes are oxidoreductases, hydrolases, lyases (catalyzing additions to double
bonds), and less generally, ligases (e.g. aldolases). Some of the enzymes and their functions are listed in
Table 1 (compiled from Ullman, Vol. A9, pp. 429-434).
Table 1. Enzymes for Asymmetric Synthesis
Examples of industrial application
Kinetic resolutions of
racemic mixtures
Pig liver esterase - asymmetric synthesis of chrysanthemic,
permethrinic, and caronic acids from the corresponding racemic
methyl esters
Chymotrypsin and acylase ­ kinetic resolution of amino acids
Hog pancreatic lipase ­ enantioselective hydrolysis of glycidyl
butyrate (>95% ee.)
Amidases ­ hydrolyze N-acylamino acids
Formation of bonds in
polypeptides and
Trypsin-catalyzed reaction ­ conversion of porcine insulin to human
Thermolysin-catalyzed reaction ­ synthesis of an aspartame precursor
Chymotrypsi, papain and trypsin ­ total synthesis of dynorphin (an
Adolases Catalyze
and formation of
carbon-carbon bonds
in carbohydrates
Fructose 1,6-diphosphate adolase ­ synthesis of rare, non-natural and
isotopically labeled carbohydrates such as D-Fructose 6-Phosphate
and L-Sorbose.
Catalyzing additions
to double bonds
-amylase and glucamylase­ conversion of starch to glucose
Glucose isomerase ­ isomerization of glucose to fructose
Aspartase ­ production of aspartic acid
Fumarase ­ production of malic acid from fumaric acid
Galactosidase ­ synthesis of glycosides
Epoxy hydrolases ­ open epoxides regiospecifically
Horse liver alcohol dehydrogenase ­ stereoselective reduction of
Enoate reductase ­ stereoselective reduction of
carbonyl compound to the saturated derivatives
Lactate dehydrogenase ­ reduced
-oxo acids enantiospecifically
-hydroxy acids

The utilization of enzymes in organic synthesis can be advantageous for several reasons (Roberts et al:
1995). Firstly, enzymes catalyze reactions under mild conditions (37°C/1 atm/pH 7). The transformations
are often remarkably energy-efficient compared to chemical processes. Secondly, enzymes often promote
highly chemoselective, regioselective, and stereoselective reactions, and being chiral catalysts, they are

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