Synthesis of octagon-containing molecular nanocarbons

Nanocarbons, such as fullerenes, carbon nanotubes, and graphenes, have long inspired the scientific community. In order to synthesize nanocarbon molecules in an atomically precise fashion, many synthetic reactions have been...

Peptide Regulation of Gene Expression: A Systematic Review

Peptides are characterized by their wide range of biological activity: they regulate functions of the endocrine, nervous, and immune systems. The mechanism of such action of peptides involves their ability to regulate gene expression and protein synthesis in plants, microorganisms, insects, birds, rodents, primates, and humans. Short peptides, consisting of 2–7 amino acid residues, can penetrate into the nuclei and nucleoli of cells and interact with the nucleosome, the histone proteins, and both single- and double-stranded DNA. DNA–peptide interactions, including sequence recognition in gene promoters, are important for template-directed synthetic reactions, replication, transcription, and reparation. Peptides can regulate the status of DNA methylation, which is an epigenetic mechanism for the activation or repression of genes in both the normal condition, as well as in cases of pathology and senescence. In this context, one can assume that short peptides were evolutionarily among the first signaling molecules that regulated the reactions of template-directed syntheses. This situation enhances the prospects of developing effective and safe immunoregulatory, neuroprotective, antimicrobial, antiviral, and other drugs based on short peptides.

Synthesis of the COFs: From Design Principle to Synthetic Reactions

Covalent organic frameworks (COFs) are a new category of materials and developing fast in recent years. COFs present low density, controllable porosity, and high surface area. Based on these merits, COFs have great potential in various applications, such as gas separation and storage, energy storage, catalysis, and many others. In this review, we summarize the synthesis of COFs from the aspects of design principles and synthetic reactions. In particular, we categorize the synthetic reactions of also COFs into six categories and introduce the advantages of each type of reaction. Moreover, we utilize several examples to illustrate how to construct COFs by these synthetic methods. In the end, a future perspective on the development of new synthetic methods for COFs is briefly mentioned.

N,N-Dimethylformamide (DMF): An Inexpensive and Attractive Reactant

: The development of simple, atom-economical, and sustainable methodologies for the construction of various functional molecules from easily available substrates has been of great interest in synthetic chemistry. N,N-dimethylformamide (DMF) is an inexpensive, abundant solvent and industrial raw material. It is considered as an effective polar solvent and a versatile reagent in synthetic transformations. During the past few decades, many significant and attractive achievements have been made in the fields of DMF as a reactant. The mini-review will mainly summarize recent advances in the applicants of DMF as a multipurpose building block in synthetic reactions.

Enzymatic Polymerization of Dihydroquercetin (Taxifolin) in Betaine-Based Deep Eutectic Solvent and Product Characterization

Deep eutectic solvents (DESs) are an alternative to conventional organic solvents in various biocatalytic reactions. Meanwhile, there have been few studies reporting on synthetic reactions in DESs or DES-containing mixtures involving oxidoreductases. In this work, we have studied the effects of several DESs based on betaine as the acceptor of hydrogen bonds on the catalytic activity and stability of laccase from the basidial fungus Trametes hirsuta and performed enzymatic polymerization of the flavonoid dihydroquercetin (DHQ, taxifolin) in a DES–buffer mixture containing 60 vol.% of betaine-glycerol DES (molar ratio 1:2). The use of the laccase redox mediator TEMPO enabled an increased yield of DHQ oligomers (oligoDHQ), with a number average molecular weight of 1800 g mol−1 and a polydispersity index of 1.09. The structure of the synthesized product was studied using different physicochemical methods. NMR spectroscopy showed that oligoDHQ had a linear structure with an average chain length of 6 monomers. A scheme for enzymatic polymerization of DHQ in a DES–buffer mixture was also proposed.

Synthesis and Antibacterial Activities of Coumarins with an Acyl Amino Side Chain

Coumarin is a heterocyclic moiety containing benzo pyran ring structure. It is widely distributed in the plant kingdom as a glycoside. Many compounds of medicinal and pharmaceutical importance possess coumarin ring structure. Drugs with coumarin structure can be synthesized by many well-known synthetic reactions. Coumarin derivatives were found to be antibacterial, anticoagulant, antiinflammatory, anti-HIV, anti-cancer and antioxidant. As part of the search for new and effective antibacterial agents, eight novel derivatives of coumarins were synthesized by Mannich reaction. All the compounds were evaluated for antibacterial activity against Staphylococcus aureus and Escherichia coli using ciprofloxacin as standard and DMSO as solvent. Three of the synthesized derivatives exhibited good antibacterial activity against Staphylococcus aureus and Escherichia coli. The work must be extended so as to develop coumarin derivatives into highly effective antibacterial agents.

Beneficial substrate partitioning boosts non-aqueous catalysis in de novo enzyme-alginate beads

Synthetic reactions often involve solvents incompatible with biocatalysts. Here, we encapsulate de novo heme-containing enzymes in calcium-alginate beads to facilitate heterogeneous biocatalysis in organic solvents. After encapsulation, enzymes remained structured and retained activity even when the beads are suspended in organic solvents. Carbene transferase activity, brought about by the heme cofactor, was enhanced when reactions were performed in organic solvent with alginate-encapsulated enzymes. Activity-solvent dependencies revealed that the activity boost is due to beneficial partitioning of the substrate between the beads and organic phase. Encapsulation furthermore facilitates enzyme recycling after the reaction. Alginate encapsulation opens up novel opportunities for biocatalysis in organic solvent systems, combining desired solvent properties of organic chemistry with enzymatic selectivity and proficiency.

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

The reversible, weak ground-state aggregate formed by dipole–dipole interactions between an electron donor and an electron acceptor is referred to as an electron-donor–acceptor (EDA) complex. Generally, upon light irradiation, the EDA complex turns into the excited state, causing an electron transfer to give radicals and to initiate subsequent reactions. Besides light as an external energy source, reactions involving the participation of EDA complexes are mild, obviating transition metal catalysts or photosensitizers in the majority of cases and are in line with the theme of green chemistry. This review discusses the synthetic reactions concerned with EDA complexes as well as the mechanisms that have been shown over the past five years.

Recent Advancements in Pyrrole Synthesis

This review article features selected examples on the synthesis of functionalized pyrroles that were reported between 2014 and 2019. Pyrrole is an important nitrogen-containing aromatic heterocycle that can be found in numerous compounds of biological and material significance. Given its vast importance, pyrrole continues to be an attractive target for the development of new synthetic reactions. The contents of this article are organized by the starting materials, which can be broadly classified into four different types: substrates bearing π-systems, substrates bearing carbonyl and other polar groups, and substrates bearing heterocyclic motifs. Brief discussions on plausible reaction­ mechanisms for most transformations are also presented.1 Introduction2 From π-Systems2.1 Alkenes2.2 1,6-Dienes2.3 Allenes2.4 Alkynes2.5 Propargylic Groups2.6 Homopropargylic Amines3 From Carbonyl Compounds3.1 Aldehydes3.2 Ketones3.3 Cyanides and Isocyanides3.4 Formamides3.5 β-Enamines3.6 Dicarbonyl Compounds4 From Polar Compounds4.1 Aminols4.2 Diols4.3 Organonitro Compounds5 From Heterocycles5.1 Münchnones5.2 Isoxazoles5.3 Carbohydrates5.4 trans-4-Hydroxy-l-prolines5.5 Pyrrolines6 Summary