Chemoenzymatic synthesis of the chiral herbicide: (S)-metolachlor

2006 ◽  
Vol 84 (8) ◽  
pp. 1058-1063 ◽  
Author(s):  
Liangyu Zheng ◽  
Suoqin Zhang ◽  
Fang Wang ◽  
Gui Gao ◽  
Shugui Cao
Keyword(s):  
Chemical Method ◽  
Kinetic Resolution ◽  
Extraction Procedure ◽  
Chemoenzymatic Synthesis ◽  
Optimal Conditions ◽  
Acid Product ◽  
Enantiomerically Pure ◽  
Hydrolytic Kinetic Resolution ◽  
Simple Chemical ◽  
Simple Extraction

A chemoenzymatic approach for the production of (S)-metolachlor, one of the most widely used herbicides, has been developed. The starting material (S)-N-(2-ethyl-6-methylphenyl)alanine was obtained by the use of lipase-catalyzed hydrolytic kinetic resolution. Under the optimal conditions, the good activity and excellent enantioselectivity of lipase B from Candida antarctica (CAL-B,E > 100) are achieved in diethyl ether – water (15% v/v), which is about 9.7-fold more enantioselective than that in a pure buffered aqueous solution (E = 12.1). After a simple extraction procedure is used to separate the acid product from the remaining ester, the remaining ester is racemized, providing the basis for the continuous resolution process. Then (S)-metolachlor is synthesized by a simple chemical method using the enantiomerically pure (S)-acid.Key words: (S)-metolachlor, herbicide, CAL-B, (S)-N-(2-ethyl-6-methylphenyl)alanine, resolution.

scholarly journals Optimization of Gallic Acid Production from Terminalia Chebula byAspergillus niger

2007 ◽  
Vol 4 (2) ◽  
pp. 287-293 ◽  
Author(s):  
N. Lokeswari ◽  
K. Jaya Raju
Keyword(s):  
Aspergillus Niger ◽  
Gallic Acid ◽  
Ellagic Acid ◽  
Condensed Tannin ◽  
Extraction Procedure ◽  
Terminalia Chebula ◽  
Optimal Conditions ◽  
Plant Phenolics ◽  
Simple Extraction ◽  
Hydrolysis Of

A method for producing gallic acid by microbiological hydrolysis of the tannins of myrobalan seed powder is described in the present work. Hydrolysis of gallotannins of the substrate to gallic acid byAspergillus nigerMTCC 282 was studied. A simple extraction procedure is used. Fungal mycelia pre-induced with 5 g/L gallotannin was used as inoculums. Optimal conditions of production were determined using various parameters including gallotannin concentration, nutritional source and metal ions are determined. Gallotannin is hydrolyzed with acid, and gallic acid in the hydrolyses is then assayed using rhodanine. This method is very specific: no interferences from other plant phenolics, including ellagic acid and condensed tannin, have been observed. The yield of gallic acid with respect to gallotannins present in the substrate is estimated. Yields of gallic acid are about 74% with respect to gallotannin concentration, which suggests that this method is exploitable industrially for the manufacturing trimethoprim drug.

A convenient synthesis of the enantiomerically pure β-blocker (S)-betaxolol using hydrolytic kinetic resolution

2005 ◽  
Vol 16 (23) ◽  
pp. 3802-3806 ◽  
Author(s):  
Ramesh A. Joshi ◽  
Dinesh R. Garud ◽  
M. Muthukrishnan ◽  
Rohini R. Joshi ◽  
M.K. Gurjar
Keyword(s):  
Kinetic Resolution ◽  
Enantiomerically Pure ◽  
Hydrolytic Kinetic Resolution ◽  
Convenient Synthesis ◽  
Β Blocker

scholarly journals Chemoenzymatic Synthesis of Apremilast: A Study Using Ketoreductases and Lipases

2021 ◽  
Author(s):  
Kimberly Vega ◽  
Daniel Cruz ◽  
Artur Oliveira ◽  
Marcos da Silva ◽  
Telma de Lemos ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Ethyl Acetate ◽  
Kinetic Resolution ◽  
Enantiomeric Excess ◽  
The Other ◽  
Chemoenzymatic Synthesis ◽  
Hydrolysis Reaction ◽  
Chiral Alcohol ◽  
Enantiomerically Pure ◽  
Enantiomeric Ratio

The key step in the chemoenzymatic synthesis of apremilast was to produce the chiral alcohol (R)-1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethanol, (R)-3. Two enzymatic approaches were evaluated to obtain (R)-3, one using ketoreductases and the other lipases. Bioreduction of 1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethanone (2), using ketoreductase KRED‑P2-D12, led to (R)-3 with 48% conversion and 93% enantiomeric excess (ee). Kinetic resolution of rac-1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethyl acetate (rac-4), via hydrolysis reaction, with 20% of n-butanol, catalyzed by lipase from Aspergillus niger yielded (R)-3 with > 99% ee, 50% conversion and E-value (enantiomeric ratio) > 200. The reaction between enantiomerically pure (R)-3 and 4-acetylamino-isoindol-1,3-dione (8) afforded apremilast in 65% yield and 67% ee.

Stereochemistry of epoxide carbonylation using bimetallic Lewis acid/metal carbonyl complexes

2004 ◽  
Vol 76 (3) ◽  
pp. 557-564 ◽  
Author(s):  
Y. D. Y. L. Getzler ◽  
Viswanath Mahadevan ◽  
E. B. Lobkovsky ◽  
G. W. Coates
Keyword(s):  
Lewis Acid ◽  
Kinetic Resolution ◽  
Metal Carbonyl ◽  
Carbonyl Complexes ◽  
Enantiomerically Pure ◽  
Metal Carbonyl Complexes ◽  
Pure Complex

The stereochemistry of epoxide carbonylation using bimetallic [Lewis acid]+[Co(CO)4]- complexes is reported. The achiral complex [(salph)Al(THF)2][Co(CO)4] stereospecifically carbonylates cis- and trans-2-butene oxide to the trans- and cis-β-lactones, respectively. Preliminary experiments regarding the carbonylative kinetic resolution of racemic trans-2-butene oxide using the enantiomerically pure complex [(R,R-salcy)Al(THF)2][Co(CO)4] are also reported.

Energy Band Gap Studies of CdS Nanomaterials

2008 ◽  
Vol 3 ◽  
pp. 97-102 ◽  
Author(s):  
Dinu Patidar ◽  
K.S. Rathore ◽  
N.S. Saxena ◽  
Kananbala Sharma ◽  
T.P. Sharma
Keyword(s):  
Optical Absorption ◽  
Band Gap ◽  
Energy Band ◽  
Chemical Method ◽  
Optical Absorption Spectroscopy ◽  
Cds Nanoparticles ◽  
X Ray Diffraction ◽  
Energy Band Gap ◽  
X Ray ◽  
Simple Chemical

The CdS nanoparticles of different sizes are synthesized by a simple chemical method. Here, CdS nanoparticles are grown through the reaction of solution of different concentration of CdCl2 with H2S. X-ray diffraction pattern confirms nano nature of CdS and has been used to determine the size of particle. Optical absorption spectroscopy is used to measure the energy band gap of these nanomaterials by using Tauc relation. Energy band gap ranging between 3.12 eV to 2.47 eV have been obtained for the samples containing the nanoparticles in the range of 2.3 to 6.0 nm size. A correlation between the band gap and size of the nanoparticles is also established.

Sign in / Sign up

Export Citation Format

Share Document