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Finding faster and simpler ways to screen protein sequence space to enable the identification of new biocatalysts for asymmetric synthesis remains both a challenge and a rate-limiting step in enzyme discovery. Biocatalytic strategies for the synthesis of chiral amines are increasingly attractive and include enzymatic asymmetric reductive amination, which offers an efficient route to many of these high-value compounds. Here we report the discovery of over 300 new imine reductases and the production of a large (384 enzymes) and sequence-diverse panel of imine reductases available for screening. We also report the development of a facile high-throughput screen to interrogate their activity. Through this approach we identified imine reductase biocatalysts capable of accepting structurally demanding ketones and amines, which include the preparative synthesis of N-substituted β-amino ester derivatives via a dynamic kinetic resolution process, with excellent yields and stereochemical purities.High-throughput biocatalytic screening and metagenomics have been used to discover over 300 imine reductases (IREDs) and subsequently produce a sequence-diverse panel of IREDs suitable for optimizing the synthesis of chiral amines. Additional characterization identified biocatalysts that accommodate structurally demanding amines and ketones for enzymatic reductive aminations.

To optimize drug candidates, modern medicinal chemists are increasingly turning to an unconventional structural motif: small, strained ring systems. However, the difficulty of introducing substituents such as bicyclo[1.1.1]pentanes, azetidines, or cyclobutanes often outweighs the challenge of synthesizing the parent scaffold itself. Thus, there is an urgent need for general methods to rapidly and directly append such groups onto core scaffolds. Here we report a general strategy to harness the embedded potential energy of effectively spring-loaded C-C and C-N bonds with the most oft-encountered nucleophiles in pharmaceutical chemistry, amines. Strain-release amination can diversify a range of substrates with a multitude of desirable bioisosteres at both the early and late stages of a synthesis. The technique has also been applied to peptide labeling and bioconjugation.

Inhibitory effect was studied by disk diffusion and agar well diffusion assay and the statistical anal- ysis was done with SPSS 16 with used of repeat measure ex- amination.

Over the past several decades, organometallic cross-coupling chemistry has developed into one of the most reliable approaches to assemble complex aromatic compounds from preoxidized starting materials. More recently, transition metal–catalyzed carbon-hydrogen activation has circumvented the need for preoxidized starting materials, but this approach is limited by a lack of practical amination protocols. Here, we present a blueprint for aromatic carbon-hydrogen functionalization via photoredox catalysis and describe the utility of this strategy for arene amination. An organic photoredox-based catalyst system, consisting of an acridinium photooxidant and a nitroxyl radical, promotes site-selective amination of a variety of simple and complex aromatics with heteroaromatic azoles of interest in pharmaceutical research. We also describe the atom-economical use of ammonia to form anilines, without the need for prefunctionalization of the aromatic component.

The piperazine moiety is often found in drugs or in bioactive molecules. This widespread presence is due to different possible roles depending on the position in the molecule and on the therapeutic class, but it also depends on the chemical reactivity of piperazine-based synthons, which facilitate its insertion into the molecule. In this paper, we take into consideration the piperazine-containing drugs approved by the Food and Drug Administration between January 2011 and June 2023, and the synthetic methodologies used to prepare the compounds in the discovery and process chemistry are reviewed.

Over the past two decades, there have been major developments in transition metal–catalyzed aminations of aryl halides to form anilines, a common structure found in drug agents, natural product isolates, and fine chemicals. Many of these approaches have enabled highly efficient and selective coupling through the design of specialized ligands, which facilitate reductive elimination from a destabilized metal center. We postulated that a general and complementary method for carbon–nitrogen bond formation could be developed through the destabilization of a metal amido complex via photoredox catalysis, thus providing an alternative approach to the use of structurally complex ligand systems. Here, we report the development of a distinct mechanistic paradigm for aryl amination using ligand-free nickel(II) salts, in which facile reductive elimination from the nickel metal center is induced via a photoredox-catalyzed electron-transfer event.

Single-atom catalysts (SACs) have emerged as a frontier in heterogeneous catalysis due to the well-defined active site structure and the maximized metal atom utilization. Nevertheless, the robustness of SACs remains a critical concern for practical applications. Herein, we report a highly active, selective and robust Ru SAC which was synthesized by pyrolysis of ruthenium acetylacetonate and N/C precursors at 900 °C in N 2 followed by treatment at 800 °C in NH 3 . The resultant Ru 1 -N 3 structure exhibits moderate capability for hydrogen activation even in excess NH 3 , which enables the effective modulation between transimination and hydrogenation activity in the reductive amination of aldehydes/ketones towards primary amines. As a consequence, it shows superior amine productivity, unrivalled resistance against CO and sulfur, and unexpectedly high stability under harsh hydrotreating conditions compared to most SACs and nanocatalysts. This SAC strategy will open an avenue towards the rational design of highly selective and robust catalysts for other demanding transformations. Single-atom catalyst (SAC) has emerged as a frontier in heterogeneous catalysis yet its robustness remains a critical concern. Here, a highly active, selective and robust Ru 1 -N 3 SAC is explored for a challenging reaction, reductive amination of aldehydes/ketones for synthesis of primary amines.

The methane, ethane, and propane in natural gas are mostly inert under ambient conditions. Mainly they are burned to produce heat. Hu et al. show that a simple cerium salt paired with an alcohol can catalytically transform these and other simple hydrocarbons into reactive radicals at room temperature (see the Perspective by Kanai). The reactions rely on light to photolytically cleave cerium alkoxide bonds, producing alkoxy radicals that strip H atoms from the hydrocarbons and regenerate the alcohol. The resultant alkyl radicals readily add to azo compounds, olefins, and aromatics. Science , this issue p. 668 ; see also p. 647 Photolysis of cerium alkoxides forms alkoxy radicals that strip H atoms from hydrocarbons to produce reactive alkyl radicals. With the recent soaring production of natural gas, the use of methane and other light hydrocarbon feedstocks as starting materials in synthetic transformations is becoming increasingly economically attractive, although it remains chemically challenging. We report the development of photocatalytic C–H amination, alkylation, and arylation of methane, ethane, and higher alkanes under visible light irradiation at ambient temperature. High catalytic efficiency (turnover numbers up to 2900 for methane and 9700 for ethane) and selectivity were achieved using abundant, inexpensive cerium salts as photocatalysts. Ligand-to-metal charge transfer excitation generated alkoxy radicals from simple alcohols that in turn acted as hydrogen atom transfer catalysts. The mixed-phase gas/liquid reaction was adapted to continuous flow, enabling the efficient use of gaseous feedstocks in scalable photocatalytic transformations.

The synthesis of primary amines via reductive amination in the presence of NH 3 and H 2 , as a green and sustainable process, has attracted much attention. In this paper, we prepared series of Ni/SiO 2 catalysts with deposition-precipitation and impregnation methods, and their catalytic performances on the reductive amination of a biomass derived compound of furfural to produce furfurylamine were studied. The catalytic activity and the yield were correlated to the structure and the surface properties of catalysts largely. The Ni/SiO 2 is of high Lewis acidity and small Ni particle with numerous large Ni flat step surface showed high activity and selectivity, it afforded a reaction rate of 12.8 h −1 and a high yield to furfurylamine around 98%. These results are superior to the most non-noble metal catalysts reported so far. Moreover, the reaction route was examined with the unit control reactions of the intermediate. To produce furfurylamine selectively, the most suitable catalyst should have the moderate but not the highest activity in activation of hydrogen and hydrogenation in the reductive amination of furfural. This work provides some useful information for the catalytic reductive amination of aldehydes both in the design of catalyst and the reaction route.

To optimize drug candidates, modern medicinal chemists are increasingly turning to an unconventional structural motif: small, strained ring systems. However, the difficulty of introducing substituents such as bicyclo[1.1.1]pentanes, azetidines, or cyclobutanes often outweighs the challenge of synthesizing the parent scaffold itself. Thus, there is an urgent need for general methods to rapidly and directly append such groups onto core scaffolds. Here we report a general strategy to harness the embedded potential energy of effectively spring-loaded C–C and C–N bonds with the most oft-encountered nucleophiles in pharmaceutical chemistry, amines. Strain-release amination can diversify a range of substrates with a multitude of desirable bioisosteres at both the early and late stages of a synthesis. The technique has also been applied to peptide labeling and bioconjugation.