19759-27-4Relevant articles and documents
LipG9-mediated enzymatic kinetic resolution of racemates: Expanding the substrate-scope for a metagenomic lipase
Thomas, Juliana Christina,Alnoch, Robson Carlos,Costa, Allen Carolina dos Santos,Bandeira, Pamela Taisline,Burich, Martha Daniela,Campos, Suelem Kluconski,de Oliveira, Alfredo Ricardo Marques,de Souza, Emanuel Maltempi,Pedrosa, Fabio de Oliveira,Krieger, Nadia,Piovan, Leandro
, (2019/05/22)
Enzymes are the main biocatalysts of biological systems and nowadays they play an important role in asymmetric organic synthesis. Microorganisms are the main source for enzymes, however, just a very small portion of them are culturable at lab conditions and, as an alternative, metagenomics approaches allow new enzymes to be accessed from so-called “non-culturable” microorganisms. Several classes of metagenomic enzymes have been described in literature. Nevertheless, studies about their potential for asymmetric biotransformation are underexploited. Therefore, we present our recent efforts to establish the substrate-scope of LipG9, a metagenomic lipase, in enzymatic kinetic resolution (EKR) of chiral substances. LipG9 was previously isolated, immobilized and successfully applied in EKR of aliphatic alcohols. In this study, a series of resolvable chiral substances were assayed with LipG9, and secondary benzyl alcohols/esters were preferentially resolved in a much superior enantioselectivity (E > 200) than those described for aliphatic alcohols (E from 4 to 63). In an opposite way, Im-LipG9 did not present activity for tertiary alcohols, amines and lactones. When compared to commercial lipases, Im-LipG9 enantioselectivity was superior to Candida rugosa lipase and equivalent to Candida antarctica lipase B. Thus, the chemo and enantioselectivity of LipG9 in EKR reactions were identified and its potential for asymmetric synthetic approaches was demonstrated.
Rhenium-catalyzed α-alkylation of enol acetates with alcohols or ethers
Umeda, Rui,Takahashi, Yuuki,Yamamoto, Takaaki,Iseki, Hideki,Osaka, Issey,Nishiyama, Yutaka
supporting information, p. 92 - 101 (2018/11/01)
When benzylic and allylic alcohols were treated with enol acetate in the presence of a catalytic amount of a rhenium complex, ReBr(CO)5, the carbon-carbon bond formation of the alcohols and enol acetate smoothly proceeded to give the corresponding ketones and aldehyde in moderate to good yields. For the reaction of allylic alcohols, γ,δ-unsaturated carbonyl compounds were obtained in good yields. When ethers were used instead of alcohols as the alkylated agent, two alkyl moieties on the ethers were utilized on the reaction.
Rhenium complex-catalyzed coupling reaction of enol acetates with alcohols
Umeda, Rui,Takahashi, Yuuki,Nishiyama, Yutaka
, p. 6113 - 6116 (2015/01/09)
The reaction of enol acetates with alcohols in the presence of a catalytic amount of a rhenium complex, such as ReBr(CO)5, produced the corresponding ketones and aldehydes in moderate to good yields. It was suggested that the preparation of an ether, an intermolecular dehydrated product, was the first step of the reaction.
Separation of enantiopure m-substituted 1-phenylethanols in high space-time yield using Bacillus subtilis esterase
Zheng, Gao-Wei,Liu, Xu-Yun,Zhang, Zhi-Jun,Tian, Ping,Lin, Guo-Qiang,Xu, Jian-He
, p. 20446 - 20449 (2013/11/06)
A recombinant Bacillus subtilis esterase (BsE) expressed in E. coli was found to exhibit excellent enantioselectivity (E was always greater than 100) towards m-substituted 1-phenylethanol acetates in the enantioselective hydrolysis reaction. An explanation for the high enantioselectivity observed towards these substrates was provided by molecular modeling. Moreover, the BsE also showed strong tolerance towards a high concentration of m-substituted 1-phenylethanol acetates (up to 1 M). Based on these excellent catalytic properties of BsE, a kind of m-substituted 1-phenylethanols, (R)-1-(3-chlorophenyl)ethanol, was efficiently synthesized in space-time yield of 920 g per L per day and 97% ee, indicating that the BsE was considered as a potentially ideal and promising biocatalyst for large-scale production of optically active m-substituted 1-phenylethanols. The Royal Society of Chemistry 2013.
Modular P-OP ligands in rhodium-mediated asymmetric hydrogenation: A comparative catalysis study
Nunez-Rico, Jose L.,Etayo, Pablo,Fernandez-Perez, Hector,Vidal-Ferran, Anton
supporting information, p. 3025 - 3035 (2013/01/15)
Highly efficient and enantioselective hydrogenation reactions for α-(acylamino)acrylates, itaconic acid derivatives and analogues, α-substituted enol ester derivatives, and α-arylenamides (25 substrates) catalyzed by chiral cationic rhodium complexes of a set of P-OP ligands have been developed. The catalytic systems derived from these P-OP ligands provided a straightforward access to enantiomerically enriched α-amino acid, carboxylic acid, amine, and alcohol derivatives that are valuable chiral building blocks. Excellent efficiencies (full conversion in all cases) and extremely high enantiomeric excesses (94-99% ee) were achieved for a wide range of α-substituted enol ester derivatives, regardless of the substitution pattern. The R-oxy group of the ligand (methoxy or triphenylmethoxy) strongly influences the enantioselectivity and catalytic activity. Greater steric bulk around the metal centre correlated to greater (or similar) enantioselectivity, but also to slower hydrogenation. Furthermore, the hydrogenation rates observed with the four model substrates follow the same trend, independently of the R-oxy group of the ligand: methyl 2-acetamidoacrylate>dimethyl itaconate>1-phenylvinyl acetate>N-(1- phenylvinyl)acetamide. A substrate-to-catalyst ratio (S/C) of up to 10,000:1 was sufficient for total hydrogenation of a model substrate of intermediate reactivity (dimethyl itaconate), and did not imply any loss in conversion or enantioselectivity. Copyright
Dynamic kinetic resolution of a wide range of secondary alcohols: Cooperation of dicarbonylchlorido(pentabenzylcyclopentadienyl)ruthenium and CAL-B
Paeivioe, Mari,Mavrynsky, Denys,Leino, Reko,Kanerva, Liisa T.
supporting information; experimental part, p. 1452 - 1457 (2011/04/22)
The substrate scope in the dynamic kinetic resolution ofsecondary alcohols was studied by using 31 structurallydifferent alcohols and isopropenyl acetate in the presence ofdicarbonylchlorido(pentabenzylcyclopentadienyl)rutheniumand Candida antarctica lipase B (Novozym 435, CAL-B) in toluene. The enzyme and the ruthenium complex were shown to function in a highly compatible manner allowing the conversion of the racemic alcohols into the (R)-acetates in practically theoretical yields and, in most cases, ee values exceeding 99%. The results are fully comparable to those published previously by using earlier reported, state-of-the-art ruthenium-based catalysts for the alcohol racemization. A clear benefit of the dicarbonylchlorido(pentabenzylcyclopentadienyl)ruthenium system, when compared to other (cyclopentadienyl)ruthenium racemization catalysts, is its simple and cost-efficient preparation. The substrate scope of 31 secondary alcohols was studied in the dynamic kinetic resolution by utilizing dicarbonylchlorido(pentabenzylcyclopentadienyl)rutheniumand Candida antarctica lipase B (CAL-B) in the acylation with isopropenyl acetate in toluene at room temperature. The secondary alcohols were transformed into highly enantiopure (R)-acetates (in most cases ee > 99%) in close to quantitative isolatedyields. Copyright
Silver triflate catalyzed acetylation of alcohols, thiols, phenols, and amines
Das, Rima,Chakraborty, Debashis
experimental part, p. 1621 - 1625 (2011/06/25)
A variety of alcohols, thiols, phenols, and amines were subjected to acetylation reaction using acetic anhydride in the presence of catalytic quantity of silver triflate. The method described has a wide range of applications, proceeds under mild conditions, does not involve cumbersome workup, and the resulting products are obtained in high yields within a reasonable time. Georg Thieme Verlag Stuttgart · New York.
A tandem and fully enzymatic procedure for the green resolution of chiral alcohols: Acylation and deacylation in non-aqueous media
Wang, Bo,Jiang, Ling,Wang, Jue,Ma, Jingbo,Liu, Min,Yu, Hongwei
experimental part, p. 980 - 985 (2011/10/04)
A green and fully enzymatic procedure for the resolution of chiral alcohols through lipase/esterase-catalyzed acylation and subsequent lipase-catalyzed aminolysis using anhydrous ammonia was demonstrated. Both enantiomers can be obtained in high ee values (up to >99%) under ambient reaction conditions. The solvent and acyl donors can be recycled, and the enzyme can be reused for up to five times.
Chiral rhodium complexes derived from electron-rich phosphine-phosphites as asymmetric hydrogenation catalysts
Etayo, Pablo,Nunez-Rico, Jose L.,Vidal-Ferran, Anton
experimental part, p. 6718 - 6725 (2012/02/05)
Two new chiral cationic rhodium(I) complexes derived from electron-rich dicyclohexylphosphine-phosphite ligands were prepared from enantiopure Sharpless epoxy ethers. The best-performing catalyst system, which bears a less bulky methyl ether moiety, exhibited remarkably high enantioselectivity (up to 99% ee) and reactivity (up to >2500 TON) in asymmetric hydrogenation reactions of various functionalized alkenes (α-(acylamino)acrylates, itaconic acid derivatives, α-substituted enol esters and α-arylenamides). Our synthetic methodology has been successfully applied to the enantioselective synthesis of the antiepileptic drug (R)-lacosamide (Vimpat).
Benzylic-acetoxylation of alkylbenzenes with PhI(OAc)2 in the presence of catalytic amounts of TsNH2 and I2
Baba, Haruka,Moriyama, Katsuhiko,Togo, Hideo
experimental part, p. 4303 - 4307 (2011/08/22)
Treatment of alkylbenzenes with (diacetoxyiodo)benzene in the presence of catalytic amounts of p-toluenesulfonamide or p-nitrobenzenesulfonamide, and molecular iodine in 1,2-dichloroethane at 60 °C gave the corresponding (α-acetoxy)alkylbenzenes in good to moderate yields. The present reaction is a simple method for the introduction of an acetoxy group to the benzylic position of alkylbenzenes.
