161024-76-6

Upstream product

• 123-20-6 vinyl n-butyrate 
• 98-85-1 1-Phenylethanol 
• 371-27-7 2,2,2-trifluoroethylbutyrate 
• 89378-61-0 R/S-α-methylbenzyl n-butyrate 
• 536-50-5 CH₃C₆H₄CH(CH₃)OH 
• 69638-96-6 isopropenyl valerate 
• 638-11-9 isopropyl butyrate 
• 98-86-2 acetophenone 
• 7476-81-5 p-chlorophenyl butanoate 
• 1445-91-6 (S)-1-phenylethanol 
• 69638-92-2 1,2-butyrideneacetate 

Downstream Products

• 1445-91-6 (S)-1-phenylethanol 
• 107-92-6 butyric acid 

Relevant academic research and scientific papers

(S)-selective dynamic kinetic resolution of secondary alcohols by the combination of subtilisin and an aminocyclopentadienylruthenium complex as the catalysts

A new procedure for the dynamic kinetic resolution (DKR) of racemic alcohols into single enantiomers is described. This procedure employs surfactant-treated subtilisin as an (S)-selective resolving catalyst and an aminocyclopentadienylruthenium complex as a racemizing catalyst. The DKR is performed best in the presence of an acyl donor such as trifluoroethyl butyrate in THF at room temperature. Eight simple secondary alcohols have been efficiently resolved with high optical purities and good yields. The subtilisin-based DKR is complementary in stereoselectivity to its lipase-based counterpart. For an acyl-carrying alcohol, both subtilisin- and lipase-based DKRs have proceeded equally well to give a pair of enantiomeric products (>99.5% ee each) with opposite optical rotations in high yields (94-95%). Copyright

Two Approaches for CAL-B-Catalyzed Enantioselective Deacylation of a Set of α-Phenyl Ethyl Esters: Organic Solvent with Sodium Carbonate and Micro-aqueous Medium

Herein, we report an efficient enantioselective cleavage of the acyl- moiety of a set of α- phenyl ethyl esters with different chain-lengths catalyzed by lipase B from Candida antarctica (CAL-B) by comparing two reactional approaches: anhydrous media with sodium carbonates and micro-aqueous medium. The deacylation is performed in organic solvent, in the presence of Na2CO3 in the first case, and by addition of a drop of phosphate buffer solution pH 7 in the second. The results show the high efficiency of the deacylation in the presence of the sodium carbonate for the enzymatic resolution of all the esters and that in term of reactivity (31% ≤ conv ≤ 50%) and selectivity (E > 200). While, during the hydrolysis in micro-aqueous media, the conversion is strongly affected by the length of the acyl-chain side, the conversion decreases from conv = 50% with the 1-phenylethyl acetate 1a to conv = 19% with 1-phenyethyl dodecanoate 6a, and this, even if the selectivity remains high (E > 89). In both conditions, the lipase CAL-B shows a high enantioselectivities in favor of (R)-1-phenyl ethanol enantiomer (conv > 45%, E > 200) but the reactivity is modulated by the form and the size of the acyl-chain side. Graphic Abstract: [Figure not available: see fulltext.].

Improved Enantioselectivity of Subtilisin Carlsberg towards Secondary Alcohols by Protein Engineering

Generally, the catalytic activity of subtilisin Carlsberg (SC) for transacylation reactions with secondary alcohols in organic solvent is low. Enzyme immobilization and protein engineering was performed to improve the enantioselectivity of SC towards secondary alcohols. Possible amino-acid residues for mutagenesis were found by combining available literature data with molecular modeling. SC variants were created by site-directed mutagenesis and were evaluated for a model transacylation reaction containing 1-phenylethanol in THF. Variants showing high E values (>100) were found. However, the conversions were still low. A second mutation was made, and both the E values and conversions were increased. Relative to that shown by the wild type, the most successful variant, G165L/M221F, showed increased conversion (up to 36 %), enantioselectivity (E values up to 400), substrate scope, and stability in THF.

Covalently Immobilized Lipase on a Thermoresponsive Polymer with an Upper Critical Solution Temperature as an Efficient and Recyclable Asymmetric Catalyst in Aqueous Media

A thermoresponsive lipase catalyst with an upper critical solution temperature (UCST) of about 26 °C was exploited by covalent immobilization of an enzyme, Pseudomonas cepacia lipase (PSL), onto poly(acrylamide-co-acrylonitrile) by glutaraldehyde coupling. The experimental conditions for the PSL immobilization were optimized. The immobilized PSL was much more stable for wide ranges of temperature and pH than free PSL. The material was also evaluated as an asymmetric catalyst in the kinetic resolution of racemic α-methylbenzyl butyrate at 55 °C in an aqueous medium and exhibited high catalytic performance and stability. Up to 50 % conversion and 99.5 % product enantiomeric excess were achieved, thus providing highly pure enantiomers. This biocatalyst could be easily recovered by simple decantation for reuse based on temperature-induced precipitation. It showed good reusability and retained 80.5 % of its original activity with a well reserved enantioselectivity in the 6th cycle. This work would shed light on the future development of new UCST-type enzyme catalysts.

Ionic-surfactant-coated subtilisin: Activity, enantioselectivity, and application to dynamic kinetic resolution of secondary alcohols

In this work, we explored the utility of ionic-surfactant-coated Bacillus licheniformis subtilisin (ISCBLS) as the catalyst for the dynamic kinetic resolution of secondary alcohols. ISCBLS was prepared by freeze-drying Bacillus licheniformis subtilisin wi

Low-temperature enzymatic hydrolysis resolution in mini-emulsion media

A low-temperature mini-emulsion medium for the enzymatic resolution of 1-phenylethanol is described for the first time. The enzymatic hydrolysis resolution of 1-phenylethyl esters with different chain-lengths in the presence of Candida antarctica lipase B in mini-emulsion media was shown to be significantly controlled by temperature. In this system, the direct effect of temperature on the mini-emulsion size was observed. For the longer 1-phenylethyl ester, 1-phenylethyl dodecanoate, the enzymatic resolution was promoted exclusively at low temperatures. The preparative mini-emulsion enzymatic reaction of 1-phenylethyl dodecanoate at 4°C afforded the isolation of (R)-phenylethanol with a yield of 36 % with an ee of 99 %. (S)-Phenylethanol was isolated with a 51 % yield with an ee of 79 %.

Combinatorial library based engineering of candida antarctica lipase a for enantioselective transacylation of sec-alcohols in organic solvent

A method for determining lipase enantioselectivity in the transacylation of sec-alcohols in organic solvent was developed. The method was applied to a model library of Candida antarctica lipase A (CalA) variants for improved enantioselectivity (E values)

Urea treated subtilisin as a biocatalyst for transformations in organic solvents

Abstract Subtilisin lyophilized from its solution in aqueous buffer in the presence of 6 M urea showed up to 50-fold increase (as compared to lyophilized subtilisin not subjected to urea treatment) in its initial rate of a transesterification reaction in anhydrous n-hexane. The lyophilization time controlling the extent of 'drying' was an important parameter. The urea treated subtilisin had five times shorter half life during heating at 100 C in hexane. The change in conformation was also reflected in its 92-fold higher activity at 15 C as compared to merely 28-fold higher activity at 45 C. The comparative enantioselectivity of urea treated subtilisin during kinetic resolution of 1-phenylethanol was expectedly lower. Its enantioselectivity during kinetic resolution of a natural substrate N-acetyl-(R,S)-phenylalanine ethyl ester in hexane was higher. Urea treated subtilisin also showed higher catalytic promiscuity during an aldol condensation. CD studies in both far UV and near UV region were also carried out to compare the two structures.

Functional expression of Serratia marcescens H30 lipase in Escherichia coli for efficient kinetic resolution of racemic alcohols in organic solvents

A lipase from Serratia marcescens H30 was cloned and functionally expressed in E. coli in soluble form (more than 80%). The recombinant lipase activity reached 25,000 U/L after optimization. Different carriers were used to immobilize the recombinant S. marcescens lipase (SmL), and LH-EP was found to be the most ideal carrier. LH-EP immobilized SmL could catalyze enantioselective resolution of racemic alcohols. Using 4-phenyl-2-butanol as the model alcohol, the effects of temperature, organic solvent, water activity, acyl donor and substrate molar ratio on the LH-EP immobilized SmL catalyzed kinetic resolution were investigated. All of these factors influenced the resolution effect to some extent. At last, a high E value of more than 200 was achieved, with ee S > 99% and a conversion of 49.9%. Further studies showed that the LH-EP immobilized SmL could also catalyze the kinetic resolution of other structure similar racemic alcohols. These results indicate that the SmL is useful for biocatalytic production of chiral alcohols. This work is the first attempt of using SmL in this field, and it further broadens the application field of SmL.

Core-Shell Composite as the Racemization Catalyst in the Dynamic Kinetic Resolution of Secondary Alcohols

Beta-Silicalite-1 core-shell microcomposites with controllable shell thickness were synthesized and used as racemization catalysts in the one-pot dynamic kinetic resolution (DKR) of secondary alcohols by using lipase-catalyzed transesterification. The inert Silicalite-1 shell covered the external acidic sites of the Beta zeolite core, suppressing dehydration and non-enantioselective transesterification of the alcohol. The alcohols could penetrate the Silicalite-1 shell to access the acidic sites at the core Beta for racemization, however, the enzymatically formed (R)-esters were excluded owing to their larger size. As a result, the high ee of the (R)-ester products was conserved and dehydration side products were minimized. Owing to the shape selective nature of the composite racemization catalyst, small and readily available acyl donors could be used in the enzyme-catalyzed transesterification to obtain the esters with high enantiopurity. The DKR of 1-phenylethanol with isopropenyl acetate using an optimized core-shell catalyst, CS-60, gave 92% selectivity to ester formation and the desired (R)-1-phenylethyl acetate was formed with 94% ee.