다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Pharmaceutical synthesis can benefit greatly from the selectivity gains associated with enzymatic catalysis Here, we report an efficient biocatalytic process to replace a recently implemented rhodium-catalyzed asymmetric enamine hydrogenation for the large-scale manufacture of the antidiabetic compound sitagliptin Starting from an enzyme that had the catalytic machinery to perform the desired chemistry but lacked any activity toward the prositagliptin ketone, we applied a substrate walking, modeling, and mutation approach to create a transaminase with marginal activity for the synthesis of the chiral amine; this variant was then further engineered via directed evolution for practical application in a manufacturing setting The resultant biocatalysts showed broad applicability toward the synthesis of chiral amines that previously were accessible only via resolution This work underscores the maturation of biocatalysis to enable efficient, economical, and environmentally benign processes for the manufacture of pharmaceuticals

https://science.sciencemag.org/content/sci/early/2010/06/17/science.1188934.full.pdf

Biocatalytic Asymmetric Synthesis of Chiral Amines from Ketones Applied to Sitagliptin Manufacture

Based on the principles and metrics of green chemistry and sustainable development, biocatalysis is both a green and sustainable technology. This is largely a result of the spectacular advances in molecular biology and biotechnology achieved in the past two decades. Protein engineering has enabled the optimization of existing enzymes and the invention of entirely new biocatalytic reactions that were previously unknown in Nature. It is now eminently feasible to develop enzymatic transformations to fit predefined parameters, resulting in processes that are truly sustainable by design. This approach has successfully been applied, for example, in the industrial synthesis of active pharmaceutical ingredients. In addition to the use of protein engineering, other aspects of biocatalysis engineering, such as substrate, medium, and reactor engineering, can be utilized to improve the efficiency and cost-effectiveness and, hence, the sustainability of biocatalytic reactions. Furthermore, immobilization of an enzyme ...

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Role of Biocatalysis in Sustainable Chemistry

The current demands of the world’s biotechnological industries are enhancement in enzyme productivity and development of novel techniques for increasing their shelf life. These requirements are inevitable to facilitate large-scale and economic formulation. Enzyme immobilization provides an excellent base for increasing availability of enzyme to the substrate with greater turnover over a considerable period of time. Several natural and synthetic supports have been assessed for their efficiency for enzyme immobilization. Nowadays, immobilized enzymes are preferred over their free counterpart due to their prolonged availability that curtails redundant downstream and purification processes. Future investigations should endeavor at adopting logistic and sensible entrapment techniques along with innovatively modified supports to improve the state of enzyme immobilization and provide new perspectives to the industrial sector.

/pdf/enzyme-immobilization-an-overview-on-techniques-and-support-23u8nfucrt.pdf

Enzyme immobilization: an overview on techniques and support materials.

Two-dimensionally extended, polycyclic heteroaromatic molecules (heterocyclic nanographenes) are a highly versatile class of organic materials, applicable as functional chromophores and organic semiconductors. In this Review, we discuss the rich chemistry of large heteroaromatics, focusing on their synthesis, electronic properties, and applications in materials science. This Review summarizes the historical development and current state of the art in this rapidly expanding field of research, which has become one of the key exploration areas of modern heterocyclic chemistry.

Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds: Synthetic Routes, Properties, and Applications

ω-Transaminases for the synthesis of non-racemic α-chiral primary amines

Asymmetric methods to prepare optically active a-chiral primary amines are highly demanded in asymmetric synthesis owing to the biological/pharmacological activity of many amines. Various techniques have been reported, such as asymmetric 1,2-addition to imines and asymmetric amination of a,a-disubstituted aldehydes, transformation of allylic alcohols into amines, (dynamic) kinetic resolution, and cyclic deracemization employing racemic amines as substrates. Asymmetric reductive amination of ketones has been investigated with transition-metal catalysts and organocatalysts, as well as via sulfinyl imine intermediates. Although tremendous progress in organo/metal catalysis has been achieved for the asymmetric reductive amination of ketones to access a-chiral amines, improved protocols are still required that are simple, green, and economically viable and that lead to high enantiomeric excesses. Biocatalytic reductive amination or transamination is well established for accessing a-amino acids from the corresponding a-keto carboxylic acids. However, the situation is different for primary amines that are not adjacent to a carbonic acid moiety. w-Transaminases have recently received attention for the preparation of such a-chiral unprotected amines. w-Transaminases are employed mainly in one way, namely for the kinetic resolution of racemic chiral amines; only a few reports deal with asymmetric synthesis by starting from a prochiral ketone, probably due to problems in shifting the equilibrium to the product side, as well as due to the moderate stereoselectivity of the employed w-transaminases. These asymmetric synthetic processes usually require at least stoichiometric amounts of an amine donor (for example, alanine). The latter leads to a side product (pyruvate), which has to be removed during the transformation by using, for instance, pyruvate decarboxylase or lactate dehydrogenase. Additionally, limitations due to inhibition by the product amine and by pyruvate have been reported. An ideal process would use ammonium as the amine donor, together with a cheap reducing agent (for example, formate, hydrogen, or glucose; see Scheme 1). Even

Formal Asymmetric Biocatalytic Reductive Amination

Various w-transaminases were tested for the synthesis of enantiomerically pure amines from the corresponding ketones employing d -o rl-alanine as amino donor and lactate dehydrogenase to remove the side-product pyruvate to shift the unfav- ourable reaction equilibrium to the product side. Both enantiomers, (R)- and (S)-amines, could be pre- pared with up to 99% ee and > 99% conversions within 24 h at 50 mM substrate concentration. The activity and stereoselectivity of the amination reac- tion depended on the w-transaminase and substrate employed; furthermore the co-solvent significantly influenced both the stereoselectivity and activity of the transaminases. Best results were obtained by em- ploying ATA-117 to obtain the (R)-enantiomer and ATA-113 or ATA-103 to access the (S)-enantiomer with 15% v v 1 DMSO.

Asymmetric Synthesis of Optically Pure Pharmacologically Relevant Amines Employing ω-Transaminases

Various recombinant ω-transaminases, overexpressed in E. coli cells and employed as whole-cell catalysts, are tested for the synthesis of enantiomerically pure amines from the corresponding prochiral ketones. Optically pure (S)-amines are obtained by formal reductive amination, consuming just ammonia and a cheap reducing agent (formate) with up to 99 % ee and 97 % yield. The other enantiomer was accessible by employing the same ω-transaminases in a kinetic resolution starting from racemic amines. A ω-transaminase derived from an Arthrobacter species displayed the highest stereoselectivity for all substrates tested, both for the kinetic resolution of rac-amines and for the amination of ketones.

Dominik Koszelewski

Papers

ω-Transaminases for the synthesis of non-racemic α-chiral primary amines

Formal Asymmetric Biocatalytic Reductive Amination

Asymmetric Synthesis of Optically Pure Pharmacologically Relevant Amines Employing ω-Transaminases

Synthesis of Optically Active Amines Employing Recombinant ω‐Transaminases in E. coli Cells

Deracemisation of α‐Chiral Primary Amines by a One‐Pot, Two‐Step Cascade Reaction Catalysed by ω‐Transaminases