A Comparative Study of Chirally Modified Platinum catalysts in Heterogeneous Enantioselective Hydrogenation

송병주,김정명,박지수,윤용주 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

Enantioselective catalysis is in interest of pharmaceutical, agrochemical and fragrance industries due to the demands for the production of enantiopure compounds. Development of heterogeneous enantioselective catalysts has attracted considerable attention because of their prominent advantages such as high reusability and ease of separation. For a systematic comparative study of heterogeneous enantioselective catalysis, we investigated the effects of transition metal doping in supports, chiral modifiers and H₂ pressure. Although transition metal doping in support induced some improvement in enantioselectivity, there was no clear correlation between support acidity and enantioselectivity. Presence of methoxy group in quinoline ring, adsorbing moiety of chiral modifier, results in augment of catalytic activity and enantioselectivity at ambient H₂ pressure but a significant decrease in enantioselectivity at high H₂ pressure.

Lipase-catalyzed Remote Kinetic Resolution of Quaternary Carbon-containing Alcohols and Determination of Their Absolute Configuration

Im, Dai-Sig,Cheong, Chan-Seong,Lee, So-Ha Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.9

The quaternary carbon-containing alcohols (1-6) were resolved enantioselectively by various lipases such as PFL (Pseudomonas fluorescens lipase), LAK (Pseudomonas fluorescens lipase), CRL (Candida rugosa lipase) and PCL (Pseudomonas cepacia lipase). The enzymatic resolution of racemic alcohol $({\pm})-2$ gave the excellent enantioselectivity in favor of (S)-2d in 99% ee, while those of the racemic alcohols (1, 3, 4, 5 and 6) gave the resolved alcohols with moderate to good enantioselectivity. Also, their absolute configurations were determined by chemical transformation to the known compounds.

Platinum nanoparticles supported on mesocellular silica foams as highly efficient catalysts for enantioselective hydrogenation

Kim, Jeongmyeong,Song, Byeongju,Hwang, Gyohyun,Bang, Yongju,Yun, Yongju Elsevier 2019 Journal of catalysis Vol.373 No.-

<P><B>Abstract</B></P> <P>Mesocellular silica foams (MCFs) with different pore size were synthesized and used as supports for Pt catalysts for enantioselective hydrogenation of ethyl pyruvate. The influences of the pore size of MCFs, the amount of Pt loading and H<SUB>2</SUB> pressure on catalytic performance of cinchonidine-modified Pt/MCFs were investigated. Both activity and enantioselectivity of the Pt/MCF catalyst increased with the increase in the pore size. These results were attributed to the fact that the larger mesopores facilitate intraparticle diffusion of bulky chiral modifier molecules and generate more chirally modified Pt sites. The performances of Pt/MCFs were compared to those of Pt supported on non-porous silica (Pt/SiO<SUB>2</SUB>) and commercial Pt/Al<SUB>2</SUB>O<SUB>3</SUB> catalysts. The 1 wt% Pt/MCFs showed superior performance than the 1 wt% Pt/SiO<SUB>2</SUB> and the commercial 1 wt% Pt/Al<SUB>2</SUB>O<SUB>3</SUB> catalysts. Furthermore, the 0.6 wt% Pt/MCF exhibited higher activity and enantioselectivity than the commercial 5 wt% Pt/Al<SUB>2</SUB>O<SUB>3</SUB>, one of the most efficient heterogeneous catalysts for this reaction, in spite of a considerably less Pt loading. At optimized reaction conditions, the Pt/MCF catalyst gave enantiomeric excess of 96% at 100% conversion. They also maintained high enantioselectivity during 10 successive reaction cycles, exhibiting high reusability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The use of MCFs as supports for Pt catalysts for heterogeneous enantioselective hydrogenation. </LI> <LI> Increase in both activity and enantioselectivity with the increase in the pore size of MCF. </LI> <LI> Superior catalytic performance of Pt/MCF catalysts over conventional Pt catalysts. </LI> <LI> Excellent performance arises from the unique large-pore structure of MCF. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enantioselective Pharmacokinetics of Sibutramine in Rat

노금한,Kyoungjin Bae,Bokyoung Min,Eunyoung Kim,Kwang-il Kwon,정태천,강원구 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.2

Racemic sibutramine is widely used to treat obesity owing to its inhibition of serotonin and noradrenaline reuptake in synapses. Although the enantioselective effects of sibutramine and its two active desmethyl-metabolites, monodesmethylsibutramine (MDS) and didesmethylsibutramine (DDS), on anorexia and energy expenditure have been elucidated, the enantioselective pharmacokinetics of sibutramine are still unclear. Therefore, we aimed to characterize the enantioselective pharmacokinetics of sibutramine and its metabolites in plasma and urine following an intravenous and a single oral administration of sibutramine in rats. The absolute bioavailability of sibutramine was only about 7%. The pharmacologically less effective S-isomer of DDS was predominant in the plasma: the Cmax and the AUCinf were 28 and 30 times higher than those of the R-isomer, respectively (p<0.001). In the urine, the concentrations of the R-isomers of hydroxylated DDS and hydroxylated and carbamoylglucuronized MDS and DDS appeared to be 11.3-, 5.1-, and 5.3-times the concentrations of the respective S-isomers. Thus, regardless of increased potency than the S-enantiomers, the R-enantiomers of the sibutramine metabolites MDS and DDS were present at lower concentrations, owing to their rapid biotransformation to hydroxylated and/or carbamoylglucuronized forms and their faster excretion in the urine. The present study is the first to elucidate the enantioselective pharmacokinetics of sibutramine in rats.

Enantioselective protonation of monofluorinated silyl enol ethers by cooperative cation-binding catalysis

Min-Jung Jung,Sushovan Paladhi,송충의 대한화학회 2023 Bulletin of the Korean Chemical Society Vol.44 No.5

Herein, we report on the successful enantioselective protonation of a range of silyl enol ethers of cyclic ketones with labile chiral secondary C F bonds by using Song’s chiral oligoethylene glycols (oligoEGs) as cation-binding catalysts in the presence of CsF and a proton source. Highly enantioselective protonations of an array of silyl enol ethers of α-fluoro tetralones and α-fluoro benzosuberones were achieved, producing corresponding chiral α-secondary α-fluoro cyclic ketones in full conversion, with up to 96% ee. Furthermore, this protocol has successfully been extended to access chiral α-choro and α-bromo cyclic ketones. This successful in situ generated fluoride ion-based stereoselective catalysis was driven by creating a densely confined chiral cage from the chiral catalyst, substrate, and CsF.

미생물 에폭사이드 가수분해효소 활성을 이용한 유기용매에서의 광학활성 para-Nitrostyrene Oxide 생산

배현철,김현숙,이수정,이은열,양승택,김희숙 한국생명과학회 2002 생명과학회지 Vol.12 No.4

방향족 에폭사이드 기질에 대한 입체선택적 가수분해 활성이 우수한 Aspergillus niger LK를 이용하여 광학활성 (S)-para-nitrostyrene oxide를 제조하였다. 수용액에서 기질 의 낮은 용해도를 극복하기 위하여 유기용매에서 광학분할 반응을 수행하였으며, 생촉매 활성 저하가 가장 적은 dodecane을 유기용매로 선정하였다. 반응온도 3$0^{\circ}C$ 및 최적 water content 2% (v/v)의 조건에서 약 10시간 정도의 반응을 통해 ee 값이 100 %인 광학적으로 순수한 (S)-para-nitrostyrene oxide를 37% 정도(이론수율 : 50 %)의 높은 수율로 얻을 수 있었다. Enantioselective resolution of racemic para-nitrostyrene oxide was investigated using epoxide hydrolase activity of Aspergillus niger LK for the production of optically pure (S)-para-nitrostyrene oxide. To overcome the poor solubility of the substrate, enantioselective hydrolysis in an organic solvent was attempted under optimized reaction conditions including reaction temperature and water content. (S)-para-Nitrostyrene oxide with high optical purity (> 99% ee) was obtained at 37% yield using fungal epoxide hydrolase-catalyzed enantioselective resolution.

Enantioselective Addition of Diethylzinc to Aldehydes in the Presence of Amino Thiocyanates Derived from L-Prolinol

진명종,Young-Mok Kim 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.2

Asymmetric metal catalysis is now recognized as the most promising area in the synthesis of optically active organic compounds. One attractive method that leads to the formation of optically active secondary alcohols is catalytic enantioselective addition of organozinc reagent to aldehyde.1 Numerous elegant and efficient catalysts have been develop- ed for this reaction, in which most of them are based on protic chiral ligands such as amino alcohols,2 diols,3 di- amines,4 and their derivatives.5 Although amino thioacetates 2 have been used with success for the diethylzinc-aldehyde addition, aprotic ligands have not received much attention in this area.6 Thus, it should be of interest to explore the catalytic ability of aprotic ligands. We present new chiral N,S-chelate aprotic ligands 3, together with their catalytic applicability in the diethylzinc-aldehyde addition.

Enantioselective Hydrolysis of Racemic Styrene Oxide by Epoxide Hydrolase of Rhodosporidium kratochvilovae SYU-08

Lee, Ji-Won,Lee, Eun-Jung,Yoo, Seung-Sik,Park, Sung-Hoon,Kim, Hee-Sook,Lee, Eun-Yeol The Korean Society for Biotechnology and Bioengine 2003 Biotechnology and Bioprocess Engineering Vol.8 No.5

Enantioselective hydrolysis for the production of chiral styrene oxide was investigated using the epoxide hydrolase activity of a newly isolated Rhodosporidium kratochvilovae SYU-08. The effects of reaction parameters - buffer type, pH, temperature, initial substrate concentrations, phenyl-1,2-ethanediol concentrations on hydrolysis rate, and enantioselectivity - were analyzed. Optically active (S)-styrene oxide with an enantiomeric excess higher than 99 % was obtained from its racemate. with a yield of 38 % (theoretically 50% maximum yield) from an initial concentration of 80 mM.

Biocatalytic Preparation of Chiral Epichlorohydrins Using Recombinant Pichia pastoris Expressing Epoxide Hydrolase of Rhodotorula glutinis

Kim, Hee-Sook,Lee, Jae-Hwa,Park, Sunghoon,Lee, Eun-Yeol The Korean Society for Biotechnology and Bioengine 2004 Biotechnology and Bioprocess Engineering Vol.9 No.1

The use of enantioselective hydrolysis for preparing chiral epichlorohydrins was investigated using recombinant Pichia pastoris with the enantioselective epoxide hydrolase of Rhodotorula glutinis. The rate of the recombinant epoxide hydrolase-catalyzed enantioselective hydrolysis of racemic epichlorohydrins was enhanced by the addition of 5%(v/v) Tween 20. Enantiopure (R)-epichlorohydrins with an enantiopurity of 100% ee and a yield of 26% were obtained within 5min from 50mM racemates.

Heterogeneous enantioselective hydrogenation over chirally modified Pt catalysts

윤용주 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

Homochirality of life on Earth has significant implications in the production of pharmaceutical compounds because the two enantiomers of chiral drugs can have different physiological impacts when they are ingested. Enantioselective heterogeneous catalysts can provide significant advantages in terms of easy separation from products and high reusability. The heterogeneous catalysts require chiral sites for enantiospecific interactions between reactants and metal particles. These can be easily created by the adsorption of a chiral compound onto the surfaces of metal particles. In this talk, I will present catalytic performances of heterogeneous Pt catalysts for enantioselective hydrogenation of α-ketoesters. The Pt catalysts have been successfully modified by cinchona alkaloids. In addition, I will discuss the influences of structural properties of supports and Pt content on the enantioselectivity of heterogeneous Pt catalysts.