Enhanced enantioselectivity of an enzymatic reaction by the sulfur functional group. A simple preparation of optically active .beta.-hydroxy nitriles using a lipase

1991 ◽  
Vol 56 (4) ◽  
pp. 1521-1524 ◽  
Author(s):  
Toshiyuki Itoh ◽  
Yumiko Takagi ◽  
Shigenori Nishiyama
Keyword(s):  
Functional Group ◽  
Enzymatic Reaction ◽  
Optically Active ◽  
Simple Preparation ◽  
Group A

Nickel-Catalyzed Electronically-Reversed Enantioselective Hydrocarbofunctionalizations of Acrylamides

Synlett ◽  
2021 ◽  
Author(s):  
Lou Shi ◽  
Wei Shu
Keyword(s):  
Nickel Catalyst ◽  
Functional Group ◽  
Optically Active ◽  
Forming Process ◽  
Carbon Bond ◽  
Bond Forming ◽  
Synthetic Strategy ◽  
Carbon Carbon Bond ◽  
Wide Range ◽  
Simple Protocol

Asymmetric hydrocarbofunctionalizations of alkenes has emerged as an efficient synthetic strategy for accessing optically active molecules via carbon-carbon bond-forming process from readily available alkenes and carbo-electrophiles. Herein, we present a summary of the efforts from our group to control the regio- and enantioselectivity of hydrocarbofunctionalizations of electron-deficient alkenes with a nickel catalyst and chiral bisoxazolidine ligand. The reaction undergoes electron-reversed hydrocarbofunctionalizations acrylamides with excellent enantioselectivity. This operationally simple protocol enables the asymmetric hydroalkylation, hydrobenzylation and hydropropargylation of acrylamides. This reaction is useful for preparing a wide range of α-branched chiral amides with broad functional group tolerance.

Simple preparation of a C8 HPLC stationary phase with an internal polar functional group

1995 ◽  
Vol 67 (20) ◽  
pp. 3809-3813 ◽  
Author(s):  
John E. O'Gara ◽  
Bonnie A. Alden ◽  
Thomas H. Walter ◽  
John S. Petersen ◽  
Carsten L. Niederlaender ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Functional Group ◽  
Simple Preparation

Microbial conversion of optically active (R) 3 Chloro-1,2-propandiol by Clavispora lusitaniae MGR5 KY209902

2021 ◽  
Vol 16 (7) ◽  
pp. 23-29
Author(s):  
Kumarasamy Suresh ◽  
Selvaraj Vasuki ◽  
Narayanan Mathiyazhagan ◽  
Ranganathan Muthusamy
Keyword(s):  
Ir Spectrum ◽  
Functional Group ◽  
Dynamic Properties ◽  
Synthetic Medium ◽  
Broad Band ◽  
Specific Rotation ◽  
Optically Active ◽  
Microbial Conversion ◽  
Ph Change ◽  
Clavispora Lusitaniae

The MCH assimilation Clavispora lusitaniae MGR5 (KY209902) was isolated from sugarcane juice using a screening medium. The preliminary assimilation was exercised with Clavispora lusitaniae MGR5 grown on synthetic medium and assimilation by pH change of the medium was observed. The specific rotation of R-3- Chloro-1,2-propanediol was -6 (c=2.5, in C2H5OH) in conditions with enatiomeric excess of 92.8 % Clavispora lusitaniae MGR5 product. The sharp peaks in HPLC spectrum of R 3 Chloro-1,2-propanediol in the retention time peak was of 2.38 min and concentration 100%. The structural and dynamic properties of R-3-Chloro-1,2-propanediol in GCMS spectrum were obtained. The IR spectrum, a shallow broad band at wavelength 3309.8 signifies the presence of O-H stretching, the narrow peak at 1087.85 indicates the presence of C=O stretching in conjugation with functional group of R- 3 Chloro-1,2-propanediol(C3H7ClO2). These results concluded that the strain assimilated with stereo inversion of R-3- Chloro-1,2-propanediol via RS 3- chloro-1,2-propanediol. The possibility to produce optically active R-3- Chloro-1,2-propanediol was discussed.

Microstructures and Functional Group Properties of Nano-Sized Chitosan Prepared by Ball Milling

2019 ◽  
Vol 948 ◽  
pp. 192-197
Author(s):  
Kartika Sari ◽  
Edi Suharyadi ◽  
Roto Roto ◽  
Kamsul Abraha
Keyword(s):  
Grain Size ◽  
Ball Milling ◽  
Milling Time ◽  
Functional Group ◽  
High Energy ◽  
Milling Process ◽  
Sem Images ◽  
Infra Red ◽  
Group A ◽  
The Fourier Transform

Nano-sized chitosan has been prepared by ball mill (High Energy Milling) with 1500 rpm to determine itsgrainz size and functional group. A nanopowder sample was prepared in the various milling time of the precusor. The milling time were 60, 120, 180, 240, 300 and 360 minutes. The Scanning Electron Microscopy (SEM)images indicated that the microstructures and grain size of as-prepared chitosan changed by increasing the milling time. The average of grain size is 15,1 nm. The Fourier Transform Infra-Red (FTIR) spectra showedthat the -OH bond shifted after milling process. The new C=O roups formedduring the milling process, because of the ordered microstructures in the nano-sized chitosan granules weredestroyed after ball millingThe surface area of the nano-sized chitosan was high, the particles tend to agglomerate since the ionic electrostatic could not prevent to form the agglomeration. The ball milling treatment was an effective method to reduce the grain size of chitosan, and functional groups will not automatically change during the milling process.

Synthesis of optically active bisdifluorocyclopropanes through a chemo-enzymatic reaction strategy

1999 ◽  
Vol 40 (31) ◽  
pp. 5739-5742 ◽  
Author(s):  
Koichi Mitsukura ◽  
Satoshi Korekiyo ◽  
Toshiyuki Itoh
Keyword(s):  
Enzymatic Reaction ◽  
Optically Active
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