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 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.
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
, 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
