4228-66-4Relevant articles and documents
Scope and limitations of reductive amination catalyzed by half-sandwich iridium complexes under mild reaction conditions
Nguyen, Dat P.,Sladek, Rudolph N.,Do, Loi H.
supporting information, (2020/07/15)
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).
Deracemization and Stereoinversion of α-Amino Acids by l-Amino Acid Deaminase
Rosini, Elena,Melis, Roberta,Molla, Gianluca,Tessaro, Davide,Pollegioni, Loredano
, p. 3773 - 3781 (2017/11/13)
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.).
Danshensu method for an industrial synthesis of isopropyl ester
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Paragraph 0043; 0045; 0048; 0049, (2017/02/24)
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.
