- Scope and limitations of reductive amination catalyzed by half-sandwich iridium complexes under mild reaction conditions
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The conversion of aldehydes and ketones to 1° amines could be promoted by half-sandwich iridium complexes using ammonium formate as both the nitrogen and hydride source. To optimize this method for green chemical synthesis, we tested various carbonyl substrates in common polar solvents at physiological temperature (37 °C) and ambient pressure. We found that in methanol, excellent selectivity for the amine over alcohol/amide products could be achieved for a broad assortment of carbonyl-containing compounds. In aqueous media, selective reduction of carbonyls to 1° amines was achieved in the absence of acids. Unfortunately, at Ir catalyst concentrations of 1 mM in water, reductive amination efficiency dropped significantly, which suggest that this catalytic methodology might be not suitable for aqueous applications where very low catalyst concentration is required (e.g., inside living cells).
- Nguyen, Dat P.,Sladek, Rudolph N.,Do, Loi H.
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supporting information
(2020/07/15)
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- Biocascade Synthesis of L-Tyrosine Derivatives by Coupling a Thermophilic Tyrosine Phenol-Lyase and L-Lactate Oxidase
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A one-pot biocascade of two enzymatic steps catalyzed by an l-lactate oxidase and a tyrosine phenol-lyase has been successfully developed in the present study. The reaction provides an efficient method for the synthesis of l-tyrosine derivatives, which exhibits readily available starting materials and excellent yields. In the first step, an in situ generation of pyruvate from readily available bio-based l-lactate catalyzed by a highly active l-lactate oxidase from Aerococcus viridans (AvLOX) was developed (using oxygen as oxidant and catalase as hydrogen peroxide removing reagent). Pyruvate thus produced underwent C–C coupling with phenol derivatives as acceptor substrate using specially designed thermophilic tyrosine phenol-lyase mutants from Symbiobacterium toebii (TTPL). Overall, this cascade avoids the high cost and easy decomposition of pyruvate and offered an efficient and environmentally friendly procedure for l-tyrosine derivatives synthesis.
- Jiang, Yiqi,Ju, Shuyun,Li, Guosi,Lian, Jiazhang,Lin, Jianping,Wu, Mianbin,Xue, Hailong,Yang, Lirong
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supporting information
(2020/02/25)
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- Deracemization and Stereoinversion of α-Amino Acids by l-Amino Acid Deaminase
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Enantiomerically pure α-amino acids are compounds of primary interest for the fine chemical, pharmaceutical, and agrochemical sectors. Amino acid oxidases are used for resolving d,l-amino acids in biocatalysis. We recently demonstrated that l-amino acid deaminase from Proteus myxofaciens (PmaLAAD) shows peculiar features for biotechnological applications, such as a high production level as soluble protein in Escherichia coli and a stable binding with the flavin cofactor. Since l-amino acid deaminases are membrane-bound enzymes, previous applications were mainly based on the use of cell-based methods. Now, taking advantage of the broad substrate specificity of PmaLAAD, a number of natural and synthetic l-amino acids were fully converted by the purified enzyme into the corresponding α-keto acids: the fastest conversion was obtained for 4-nitrophenylalanine. Analogously, starting from racemic solutions, the full resolution (ee >99%) was also achieved. Notably, d,l-1-naphthylalanine was resolved either into the d- or the l-enantiomer by using PmaLAAD or the d-amino acid oxidase variant having a glycine at position 213, respectively, and was fully deracemized when the two enzymes were used jointly. Moreover, the complete stereoinversion of l-4-nitrophenylalanine was achieved using PmaLAAD and a small molar excess of borane tert-butylamine complex. Taken together, recombinant PmaLAAD represents an l-specific amino acid deaminase suitable for producing the pure enantiomers of several natural and synthetic amino acids or the corresponding keto acids, compounds of biotechnological or pharmaceutical relevance. (Figure presented.).
- Rosini, Elena,Melis, Roberta,Molla, Gianluca,Tessaro, Davide,Pollegioni, Loredano
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p. 3773 - 3781
(2017/11/13)
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- The industrialization to a method for synthesizing danshensu
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The invention relates to an industrial synthesis method of bornyl tanshinol, which comprises the following step: in the presence of the second hydrochloric acid, a reducing agent Zn-Hg and a catalyst, beta-(3,4-dihydroxylphenyl)pyruvic acid reacts with borneol in a solvent to generate the bornyl tanshinol, wherein the beta-(3,4-dihydroxylphenyl)pyruvic acid is obtained by hydrolyzing 2-methyl-4-(3,4-diacetoxylbenzal)oxazole in the first hydrochloric acid. In the method provided by the invention, esterification and modification reducing reaction are performed at the same time. The synthesis of an intermediate product tanshinol in a synthesis method is omitted, the process operation is simplified, and the production period is shortened. Moreover, since the beta-(3,4-dihydroxylphenyl)pyruvic acid is directly obtained by hydrolyzing 2-methyl-4-(3,4-diacetoxylbenzal)oxazole in the hydrochloric acid solution, the process operation is further simplified.
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Paragraph 0044; 0049; 0050
(2017/01/12)
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- Danshensu method for an industrial synthesis of isopropyl ester
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The invention relates to an industrial synthesis method of isopropyl tanshinol, which comprises the following step: in the presence of the second hydrochloric acid and a reducing agent Zn-Hg, beta-(3,4-dihydroxylphenyl)pyruvic acid reacts with isopropyl ester in a solvent to generate the isopropyl tanshinol, wherein the beta-(3,4-dihydroxylphenyl)pyruvic acid is obtained by hydrolyzing 2-methyl-4-(3,4-diacetoxylbenzal)oxazole in the first hydrochloric acid. In the method provided by the invention, esterification and modification reducing reaction are performed at the same time. The synthesis of an intermediate product tanshinol in a synthesis method is omitted, the process operation is simplified, and the production period is shortened. Moreover, since the beta-(3,4-dihydroxylphenyl)pyruvic acid is directly obtained by hydrolyzing 2-methyl-4-(3,4-diacetoxylbenzal)oxazole in the hydrochloric acid solution, the process operation is further simplified.
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Paragraph 0043; 0045; 0048; 0049
(2017/02/24)
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- Tyrosinase and Layer-by-Layer supported tyrosinases in the synthesis of lipophilic catechols with antiinfluenza activity
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Catechol derivatives with lipophilic properties have been selectively synthesized by tyrosinase in high yield avoiding long and tedious protection/deprotection steps usually required in traditional procedures. The synthesis was effective also with immobilized tyrosinase able to perform for more runs. The novel catechols were evaluated against influenza A virus, that continue to represent a severe threat worldwide. A significant antiviral activity was observed in derivatives characterized by antioxidant activity and long carbon alkyl side-chains, suggesting the possibility of a new inhibition mechanism based on both redox and lipophilic properties.
- Bozzini, Tiziana,Botta, Giorgia,Delfino, Michela,Onofri, Silvano,Saladino, Raffaele,Amatore, Donatella,Sgarbanti, Rossella,Nencioni, Lucia,Palamara, Anna Teresa
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p. 7699 - 7708
(2014/01/06)
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- Green synthesis of β-(3,4-dihydroxyphenyl)lactic acid
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A new method has been developed for the synthesis of β-(3,4- dihydroxyphenyl)lactic acid, an active ingredient for the treatment of myocardial ischemia. Pd/C catalysts were used in the key reduction reaction to replace the traditionally used toxic Zn/Hg catalysts. A significantly high product yield of 99.7 % was obtained under the optimal reaction conditions, through the use of orthogonal experimental design, when reaction temperature, catalyst (5 % Pd/C) amount and pressure were 60 °C, 20 wt % and 1.0 MPa, respectively.
- Zhang, Qun-Zheng,Wang, Yi,Nan, Ye-Fei,Xiong, Xun-Yu,Pan, Qing,Zhang, Xun-Li
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p. 7158 - 7160
(2013/08/23)
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- SUBSTITUTED BETA-PHENYL-ALPHA-HYDROXY PROPANOIC ACID, SYNTHESIS METHOD AND USE THEREOF
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The present invention relates to a compound of the formula (I), wherein R1, R2 and R3 are each independently selected from H, OH, F, Cl, Br, methoxy and ethoxy; or alternatively, R1 and R2 together form -OCH2O-, R3 is selected from H, OH, methoxy, ethoxy and halogens; R4 is OH or acyloxy; R5 is cycloalkoxyl, amino and substituted amino, and when R5 is selected from amino, at least one of R1, R2 and R3 is not H. The present invention further relates to a process for synthesizing a compound of the formula (I), and use of the compound of the formula (I) in the manufacture of a medicament for the prevention or treatment of cardiovascular or cerebrovascular diseases.
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Page/Page column 6
(2009/02/10)
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