Over the recent decade tremendous interest has been developed on the synthetic modification of natural as well as non‐proteinogenic amino acids and non‐natural linkages due to their immensely ...important applications in proteomics, diagnosis, and drug delivery etc. They are synthetically important also. For example, due to the high natural abundance of enantiopure amino acids, they and their derivatives are regularly employed in the development of several interesting synthetic methods, total syntheses of biologically related structures as well as in ligand elaboration. Thus, the synthetic field possesses a direct impact on several basic and applied sciences. But up to date only limited numbers of reviews are available which either appeared almost half a decade earlier or covered very specific areas of this highly expanding topic. Many achievements have already been realized in this field in the meantime which urgently need to be documented. Therefore, to meet the need this review is intended to cover the emerging versatile synthetic methods on the modification of amino acids and related structures over the recent decade with the relevant details of their respective prospects and problems in the best possible systematic and concise manner. Wherever needed relevant mechanistic details are also described.
Nickel catalysis for biaryl coupling reactions has received significant attention as a less expensive and less toxic alternative to “standard” palladium catalysis. Here we describe recent ...developments in nickel‐catalyzed biaryl coupling methodology, along with mechanistic studies and applications. In particular we focus on nickel‐catalyzed coupling reactions in which “unreactive” bonds such as C–H, C–O, and C–C bonds are converted into biaryl moieties.
Biaryl coupling through nickel catalysis has been known for a few decades. The topic has recently resurfaced in synthetic chemistry, however, thanks to its use of ideal coupling partners such as simple arenes (Ar–H) and phenol derivatives (Ar–OR). In this microreview, recent achievements in nickel‐catalyzed biaryl coupling are summarized.
A new iron‐facilitated silver‐mediated radical 1,2‐alkylarylation of styrenes with α‐carbonyl alkyl bromides and indoles is described, and two new C−C bonds were generated in a single step through a ...sequence of intermolecular C(sp3)−Br functionalization and C(sp2)−H functionalization across the alkenes. This method provides an efficient access to alkylated indoles with broad substrate scope and excellent selectivity.
Bridging alkene: An intermolecular arene C(sp2)−H functionalization strategy is established for the radical 1,2‐alkylarylation of styrenes with α‐carbonyl alkyl bromides and indoles using iron as the catalyst and silver as the promotor. This method enables the formation of two C−C bonds in a single reaction. acac=acetylacetonate.
Its even more than a centennial that the systematic researches of chemical alteration of sugars have been advancing. Out of all the interest in the field of N‐glycoside has assembled pace over the ...past few years. Therefore, N‐functionalization of sugar is one of the most fundamental modifications along with other group like azide, amide etc also play a remarkable role in the field of glycoscience. Different approaches to access structurally modified N‐glycosides in carbohydrate derivatives are reviewed. The goal of this review is to provide an overview of different way of N‐functionalization of amino sugar and induction of nitrogen scaffolds for the synthesis of various orthogonal protective groups of the N‐glycoside. The N‐functionalization of sugars designate as follows: (a) glycosylamine, (b) glycosyl azide, and (c) introduction of N‐functionality to the sugar for formation of N‐glycosides. This is the first review focus on N‐functionalization of sugars which will be a future scope that influence the readers to work in this area further.
The aim of this review is to present the advancement that took place in the field of N‐functionalization or N‐glycosylation by describing all the possible mechanistic pathways that had been followed till date and their outstanding applications. This review may also guide the readers to further explore this field.
Combined cross-linked enzyme aggregates of cyclodextrin glucanotransferase (CGTase) and maltogenic amylase (Mag1) from Bacillus lehensis G1 (Combi-CLEAs-CM) were successfully developed to synthesis ...maltooligosaccharides (MOS). Yet, the poor cross-linking performance between chitosan (cross-linker) and enzymes resulting low activity recovery and catalytic efficiency. In this study, we proposed the functionalization of cross-linkers with the integration of computational analysis to study the influences of different functional group on cross-linkers in combi-CLEAs development. From in-silico analysis, O-carboxymethyl chitosan (OCMCS) with the highest binding affinity toward both enzymes was chosen and showed alignment with the experimental result, in which OCMCS was synthesized as cross-linker to develop improved activity recovery of Combi-CLEAs-CM-ocmcs (74 %). The thermal stability and deactivation energy (205.86 kJ/mol) of Combi-CLEAs-CM-ocmcs were found to be higher than Combi-CLEAs-CM (192.59 kJ/mol). The introduction of longer side chain of carboxymethyl group led to a more flexible structure of Combi-CLEAs-CM-ocmcs. This alteration significantly reduced the Km value of Combi-CLEAs-CM-ocmcs by about 3.64-fold and resulted in a greater Kcat/Km (3.63-fold higher) as compared to Combi-CLEAs-CM. Moreover, Combi-CLEAs-CM-ocmcs improved the reusability with retained >50 % of activity while Combi-CLEAs-CM only 36.18 % after five cycles. Finally, maximum MOS production (777.46 mg/g) was obtained by Combi-CLEAs-CM-ocmcs after optimization using response surface methodology.
•Functional group on cross-linker played a vital role in cross-linking process.•Integration of computational analysis in CLEAs technology is promising.•Improved overall enzymatic properties of Combi-CLEAs-CM-ocmcs.•Longer length of carboxymethyl group led to flexible structure and improved Kcat/Km.•Combi-CLEAs-CM-ocmcs showed high production of MOS from starch after optimization.
In recent years, visible‐light‐induced C−H bond functionalization has become an emerging field at the forefront of organic chemistry. In a general sense, these approaches rely on the capability of ...metal complexes and organic dyes to convert visible light into chemical energy by engaging in single‐electron transfer with organic substrates, thus generating reactive intermediates. This review covers most of the strategies involving visible light‐induced benzylic and non‐benzylic alkylation, halogination, oxidation, vinylation, arylation, benzylation, acetylation, formylation, thiocyanation, xanthylation, azidation, amination, addition, and coupling reactions of sp2 and sp3 C−H bonds.
The development of smart biomedical devices as efficient tools in early diagnosis and therapy monitoring has recently witnessed unprecedented growth, becoming an emerging field in biomedical ...engineering. Sponges for endoluminal vacuum therapy, which are intended for transmitting negative pressure as trigger for tissue regeneration and for draining infections in anastomotic leakages, are massively used implants with very complex geometry and high risk of infection. In this work, commercial polyurethane (PU) sponges have been converted into smart biomedical devices by incorporating an electrochemical sensor to monitor the growth of bacteria. Such innovative approach, which allows to track the tissue healing process avoiding further infection development, has been performed applying a three-step process: 1) activation of PU using low pressure oxygen plasma; 2) incorporation of conducting polymer (CP) nanoparticles (NPs) at the surface of the activated PU by chemical oxidative polymerization; and 3) formation of a homogeneous electroactive coating using the CP NPs obtained in 2), as growth nuclei in an electrochemical polymerization. The functionalized PU sponge is able to monitor the bacteria growth in the surrounding media by detecting the concentration of nicotinamide adenine dinucleotide (NADH) from respiration reactions in the cytosol (i.e. bacteria do not have mitochondria). Conversely, respiration in normal eukaryotic cells takes place in the mitochondria, whose double membrane is not permeable to NADH. The sensing performance of the CP-coated PU sponges (limit of detection: 0.06 mM; sensitivity: 1.21 mA/cm2) has been determined in the lab using NADH solutions, while a proof of concept have been conducted using Escherichia coli bacteria cultures.
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•PFOTES was used to enhanced the tribo-polarity and hydrophobicity of CNF-based TENG.•PFOTES-CNF-based TENG exhibit enhanced triboelectric performance.•The Isc reached 9.3 μA, which is about twice ...that of a pure CNF-based TENG.•The PFOTES-CNF-based TENG retains 70% of the initial output at 70% ambient humidity.
Cellulose is the most abundant natural polymer on earth. Because it is renewable, biodegradable, and biocompatible, it offers distinct advantages as a starting material for bio-based triboelectric nanogenerator (bio-TENG). However, weak polarity, poor hydrophobicity, and insufficient functionalization on the natural cellulose surface severely limit the development of high-performance cellulose-based TENGs. In this work, chemical functionalization is employed to control the surface polarizability and hydrophobicity of cellulose nanofibrils (CNFs). Functional groups on the CNF surface are modified with triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane (PFOTES) in a straightforward and facile process. Fluorine-bearing silane chains are grafted to the surface of CNFs, which increases their triboelectric charge density and improves their hydrophobicity. Experimental results demonstrate that the surface polarity of CNFs is greatly improved after PFOTES modification. The PFOTES-CNF-based TENG exhibits good resistance to humidity and long-term cycle stability, and it retains 70% of the initial output performance at 70% ambient humidity. The short-circuit current of the PFOTES-CNF-based TENG reached 9.3 μA, which is about twice that of CNF-based TENG prior to modification. These results clearly indicate that PFOTES can be used to control CNF surface polarizability and hydrophobicity, advancing the search for durable, high-performance, degradable bio-TENGs.
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In recent years, transition metal-catalyzed C(sp3)H functionalization has gradually emerged as a practical and powerful tool to prepare highly valuable chemicals. In this mini-review, ...we will give some examples to cover recent research advances on transition-metal (Pd, Ni) catalyzed C(sp3)H functionalization via bidentate directing group coordination. Different bidentate directing groups will be discussed. As the whole field of transition metal-catalyzed C(sp3)H functionalization keeps moving forward, more synthetically useful chemo-, regio-, diastereo-, and enantioselective reactions catalyzed by transition-metal with bidentate directing group coordination will be discovered in the future and this promising and attractive strategy will play a more critical role in modern organic synthesis.
We report here an operationally simple protocol for the direct aromatic perfluoroalkylation and trifluoromethylation of α‐cyano arylacetates. This metal‐free approach, which occurs at ambient ...temperature and under visible‐light irradiation, is driven by the photochemical activity of electron donor–acceptor (EDA) complexes, formed in situ by the interaction of transiently generated enolates and perfluoroalkyl iodides. Preliminary mechanistic studies are reported.
Shining light: An operationally simple protocol for the direct aromatic perfluoroalkylation and trifluoromethylation of α‐cyano arylacetates requires the irradiation by visible light at ambient temperature. This metal‐free reaction is driven by the photochemical activity of electron donor–acceptor (EDA) complexes, formed in situ by the interaction of transiently generated enolates and perfluoroalkyl iodides.
