• Bulletin of the Korean Chemical Society
• /
• v.17 no.12
• /
• pp.1135-1142
• /
• 1996

Reaction of diethylzinc with α-branched aldehydes in the presence of a catalytic amount (5 mol %) of various β-amino thiols in toluene or ether provided the corresponding secondary alcohols in outstanding ee. Detailed preparative procedure for the β-amino thiols are presented.

• Bulletin of the Korean Chemical Society
• /
• v.14 no.3
• /
• pp.317-318
• /
• 1993

• Proceedings of the PSK Conference
• /
• 2001.04a
• /
• pp.220.2-220.2
• /
• 2001

• Proceedings of the PSK Conference
• /
• 2001.10a
• /
• pp.235.1-235.1
• /
• 2001

• Proceedings of the PSK Conference
• /
• 2000.10a
• /
• pp.213.2-213.2
• /
• 2000

• Proceedings of the PSK Conference
• /
• 2002.04a
• /
• pp.186.2-186.2
• /
• 2002

• Proceedings of the PSK Conference
• /
• 2002.04a
• /
• pp.219.1-219.1
• /
• 2002

• Journal of Life Science
• /
• v.15 no.5 s.72
• /
• pp.772-778
• /
• 2005

Chiral epoxides are important chiral synthons in organic synthesis for the production of chiral pharmaceuticals and functional food additives. Chiral epoxides can be synthesized by enantioselective introduction of oxygen to double bond of substrate by monooxygenase. Peroxidase also carry out asymmetric epoxidation of alkene in the presence of hydrogen peroxide. Kinetic resolution of racemic epoxides via enantioselective hydrolysis reaction by epoxide hydrolase (EH) is a very promising method since chiral epoxides with a high optical purity can be obtained from cheap and readily available racemic epoxides. In this review, various biocatalytic approaches for the production of chiral epoxides with several examples are presented and their commercial potential is discussed.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.11
• /
• pp.1810-1818
• /
• 2015

For the synthesis of various pharmaceuticals, chiral alcohols are useful intermediates. Among them, (R)-ethyl-4-chloro-3-hydroxybutanoate ((R)-ECHB) is an important building block for the synthesis of L-carnitine. (R)-ECHB is produced from ethyl-4-chloro-3-oxobutanoate (ECOB) by a reductase-mediated, enantioselective reduction reaction. The Saccharomyces cerevisiae YOL151W reductase that is expressed in Escherichia coli cells exhibited an enantioselective reduction reaction toward ECOB. By virtue of the C-terminal His-tag, the YOL151W reductase was purified from the cell-free extract using Ni²⁺-NTA column chromatography and immobilized onto Ni²⁺-magnetic microparticles. The physical properties of the immobilized reductase (Imm-Red) were measured using electron microscopy, a magnetic property measurement system, and a zeta potential system; the average size of the particles was approximately 1 μm and the saturated magnetic value was 31.76 emu/g. A neodymium magnet was used to recover the immobilized enzyme within 2 min. The Imm-Red showed an optimum temperature at 45℃ and an optimum pH at 6.0. In addition, Bacillus megaterium glucose dehydrogenase (GDH) was produced in the E. coli cells and was used in the coupling reaction to regenerate the NADPH cofactor. The reduction/oxidation coupling reaction composed of the Imm-Red and GDH converted 20 mM ECOB exclusively into (R)-ECHB with an e.e._p value of 98%.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.9
• /
• pp.1300-1306
• /
• 2010

Ethyl (R, S)-4-chloro-3-hydroxybutanoate (ECHB) is a useful chiral building block for the synthesis of L-carnitine and hypercholesterolemia drugs. The yeast reductase, YOL151W (GenBank locus tag), exhibits an enantioselective reduction activity, converting ethyl-4-chlorooxobutanoate (ECOB) exclusively into (R)-ECHB. YOL151W was generated in Escherichia coli cells and purified via Ni-NTA and desalting column chromatography. It evidenced an optimum temperature of $45^{\circ}C$ and an optimum pH of 6.5-7.5. Bacillus subtilis glucose dehydrogenase (GDH) was also expressed in Escherichia coli, and was used for the recycling of NADPH, required for the reduction reaction. Thereafter, Escherichia coli cells co-expressing YOL151W and GDH were constructed. After permeablization treatment, the Escherichia coli whole cells were utilized for ECHB synthesis. Through the use of this system, the 30 mM ECOB substrate could be converted to (R)-ECHB.