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A convenient DMAP-catalysed decarboxylative amination of aryl and alkyl carboxylic acids is developed under transition-metal-free conditions. This reaction allows the sustainable synthesis of a wide range of aryl and alkyl amines in useful to good yields, avoiding the use of any activating reagent, transition-metal catalyst and external oxidant. The late-stage modification of bioactive acids and concise synthesis of carbamate and ureas demonstrated the synthetic potential of this methodology.

Alcohols and carboxylic acids have been established as versatile building blocks in the assembly of various carbon frameworks. The deoxygenative functionalisation is one of the most attractive approaches for the conversion of these abundant materials into high-value products. However, the direct deoxygenative transformation under mild conditions has long been a challenging task in organic synthesis due to the lack of efficient methods for the activation of strong C–O bonds (102 kcal mol−1). Recently, the strategy of visible light photocatalytic phosphoranyl radical fragmentation provides a novel and powerful platform for C–O, N–O and SO bond activation. This highlight mainly discusses recent breakthroughs in phosphoranyl radical-mediated deoxygenative functionalisations of alcohols, carboxylic acids, oximes and sulfoxides with a particular emphasis on reaction scopes and mechanism.

Attempts to the construction of B/C ring and E ring in melotenine A are described. Based on para-dienone chemistry, a tactical application of tandem aminolysis/aza-Michael addition reaction was made to access highly functionalized building blocks with the pyrrolo[2,3-d]carbazole tetracyclic unit (A/B/C/D ring). Albeit negative results for assembling the dihydroazepine unit (E ring) by using the proposed fragmentation reaction of gem-dihalocyclopropanes, an alternative strategy based on ring closing metathesis was evolved to forge the E ring possessing a twisted 1,3-diene unit embedded in the rigid skeleton of melotenine A.

Aryl carboxylic acids are stable and readily available in great structural diversity both from natural and well-established synthetic procedures, which make them promising starting materials in organic synthesis. The conversion of benzoic acids into high-value molecules is of great importance and have gained much interest of synthetic chemists. The recent development of single-electron (1e−) activation strategy has been esteemed as a complementary method for the transformation of benzoic acids. In this context, carboxylate groups can be selectively transferred into reactive aryl carboxylic radical, aryl radical, and acyl radical by electrocatalysis, photocatalysis, or in the presence of some SET oxidants. Based on these radical species, remarkable advancements have been achieved for the rapid formation of various chemical bonds over the past 10 years. In this review, we summarize recent advances in single electron activation of aryl carboxylic acids, with an emphasis on reaction scope, catalytic system, limitation, and underlying reaction mechanism., Graphical Abstract, Catalysis; Organic Chemistry; Physical Organic Chemistry; Molecular Electrochemistry

Nine types of diversely fused heterocyclic quaternary ammonium salts were constructed through an oxidative CH annulation reaction. Both high-valent pentamethylcyclopentadienylcobalt(III) and pentamethylcyclopentadienyliridium(III) were found to be effective as catalyst for this reaction. Broad substrate scope and good functional group tolerance were observed.

The present study aimed to investigate the antitumor efficacy of di-2-pyridylketone-4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC) and di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT) on head and neck squamous cell carcinoma (HNSCC) cells. The proliferation and apoptosis of HNSCC cells treated with the iron chelators DpC and Dp44mT were detected. The mechanism of DpC-induced apoptosis on HNSCC cells was investigated. The human HNSCC cell lines FaDu, Cal-27 and SCC-9 were cultured in vitro and exposed to gradient concentrations of DpC and Dp44mT. A Cell Counting Kit-8 assay was used to detect the viability of FaDu, Cal-27, SCC-9 cells. Double staining with annexin V and propidium iodide was performed for the detection of the proportion of apoptotic FaDu, Cal-27 and SCC-9 cells following treatment. The nuclear damage to Cal-27 cells that were treated with DpC was detected by Hoechst staining. Finally, western blot analysis was used to detect the expression of proteins associated with the DNA damage pathway in Cal-27 cells that were treated with DpC. The CCK-8 assay showed that treatment with DpC and Dp44mT was able to markedly inhibit the viability of FaDu, Cal-27 and SCC-9 cells in a concentration-dependent manner. In comparison to Dp44mT, treatment with DpC exhibited a more effective inhibitory effect on the viability of HNSCC cells. The proportion of apoptotic cells detected by flow cytometry increased in a dose-dependent manner in all cell lines following DpC and Dp44mT treatment, with the proportion of apoptotic HNSCC cells induced by DpC treatment being significantly higher compared with Dp44mT (P

The adamantyl group is prevalent as a key pharmacophore element in drugs. We describe herein a palladium-catalyzed C–H functionalization logic for the methylene C(sp3)–H arylation of the adamantyl scaffold with the assistance of an amide group. The resulting arylated adamantyl amide was smoothly converted to an amine, providing facile access to the memantine analog.

The aim of this study was to determine the mechanisms driving the protective effects of squid ink polysaccharide (SIP) against cyclophosphamide (CP)-induced testicular damage, focusing on germ cells. In the testes of mice exposed to CP and/or SIP, the present study examined the levels of reactive oxygen species (ROS) and malondialdehyde, activity of superoxide dismutase levels, protein expression levels of B-cell lymphoma 2 (Bcl2), Bcl2-associated X protein (Bax), and total Caspase 3, activation of p-p38 and p-Akt proteins, and tissue morphology. The findings indicated that CP induced ROS production and oxidative stress, resulting in testicular damage. However, under administration of SIP, oxidative stress was impaired and the testicular toxicity induced by CP was weakened, which implied that SIP may have an important role in preventing chemotherapeutic damage to the male reproductive system via promoting antioxidant ability. Furthermore, the altered expression levels, including the upregulation of Bax and Caspase 3, downregulation of Bcl-2 and the increased Bax/Bcl-2 ratio, indicated that apoptosis occurred in CP exposed testes of mice; however, the alterations were reversed in mice treated with SIP. Moreover, in CP-exposed testes, p38 and Akt proteins were significantly phosphorylated (P

An oxidative dearomatizing cyclization of arylamines promoted by iodobenzene bis(trifluoroacetate) [PhI(CF3CO2)(2)] has been explored, leading to a novel synthetic approach to functionalized spirocyclic building blocks containing the structurally unique dieniminium moiety. This unprecedented methodology, featuring oxidative dearomatization and carbon-carbon bond-forming cyclization, to some extent, not only expands the synthetic potential of hypervalent iodine chemistry, but also enriches the oxidation chemistry of arylamines.

In our recent reports, a squid ink polysaccharide (SIP) was found having preventive activity against cyclophosphamide induced damage in mouse testis and ovary. Here we further reveal the regulative mechanism of SIP against chemical toxicity on testis. Leydig cells exposed to acrolein (ACR) underwent apoptosis at 12h and 24h. Before apoptosis, cells occurred autophagy that was confirmed by high autophagic rate and Beclin-1 protein content at 3h. PI3K/Akt and p38 MAPK signal pathways involved in the regulatory mechanisms. These outcomes of ACR were recovered completely by SIP, which was demonstrated by attenuated disruption of redox equilibrium and increased testosterone production, through suppressing ACR-caused autophagy and apoptosis regulated by PI3K/Akt and p38 MAPK signal pathways in Leydig cells. Summarily, autophagy occurred before apoptosis caused by ACR-activated p38 MAPK and PI3K/Akt pathways were blocked by SIP, resulting in survival and functional maintenance of Leydig cells.

In the paper, an accurate and sensitive system was used to monitor the ambient atmospheric NO 2 concentrations. This system utilizes cavity attenuated phase shift spectroscopy(CAPS), a technology related to cavity ring down spectroscopy(CRDS). Advantages of the CAPS system include such as: (1) cheap and easy to control the light source, (2) high accuracy, and (3) low detection limit. The performance of the CAPS system was evaluated by measuring of the stability and response of the system. The minima (~0.08 ppb NO 2 ) in the Allan plots show the optimum average time(~100s) for optimum detection performance of the CAPS system. Over a 20-day-long period of the ambient atmospheric NO 2 concentrations monitoring, a comparison of the CAPS system with an extremely accurate and precise chemiluminescence-based NOx analyzer showed that the CAPS system was able to reliably and quantitatively measure both large and small fluctuations in the ambient nitrogen dioxide concentration. The experimental results show that the measuring instrument results correlation is 0.95.

Superconductor mixed oxides were often used as catalysts at higher temperature in gas phase oxidations, and considered not suitable for lower temperature reactions in the liquid-solid phase; here the catalysis of YBa2Cu3O7+/-x and Y2BaCuO5+/-x in the phenol hydroxylation at lower temperature with H2O2 as oxygen donor was studied, and found that the superconductor YBa2Cu3O7+/-x, has no catalytic activity for phenol hydroxylation, but Y2BaCuO5+/-x does, even has better catalytic activity and stability than most previously reported ones. With the studies of catalysis of other simple metal oxides and perovskite-like mixed oxides, a radical substitution mechanism is proposed and the experimental facts are explained clearly, and draw a conclusion that the perovskite-like mixed oxides with (AO)(ABO(3)) and (AO)2(ABO(3)) structure have better catalytic activity than the simple perovskite oxides with (ABO(3))(3) structure alone, and (AO) structure unit is the key for the mixed oxides to have the phenol hydroxylation activity. No pollution of this process is very important for its further industrial application.

Lysozymes are key proteins to invertebrates in the innate immune responses against bacterial infections. A lysozyme gene isolated from tiger shrimp, Penaeus monodon, was cloned, sequenced and characterized. The cDNA consists of a signal peptide of 18 amino acids and a mature peptide of 140 amino acids. The lysozyme is presumed to be a chicken-type lysozyme for it possesses two catalytic sites and eight cysteine residues which are highly conserved across species of chicken-type lysozymes. The lysozyme cDNAs of Penaeus semisulcatus, Litopenaeus vannamei, Macrobrachium nipponense and Macrobrachium rosenbergii were also cloned. High similarities existed among shrimp and prawn lysozymes but phylogenetic relationship of shrimps and prawns based on lysozyme molecules did not quite consistent with traditional taxonomic classification. High mRNA expression was detected in hepatopancreas, haemocytes and gill of tiger shrimp. Recombinant lysozyme exhibited potent lytic activities against fish pathogens providing evidence of the involvement of lysozyme in shrimp immunity.

An oxidative dearomatizing cyclization of arylamines promoted by iodobenzene bis(trifluoroacetate) [PhI(CF3CO2)(2)] has been explored, leading to a novel synthetic approach to functionalized spirocyclic building blocks containing the structurally unique dieniminium moiety. This unprecedented methodology, featuring oxidative dearomatization and carbon-carbon bond-forming cyclization, to some extent, not only expands the synthetic potential of hypervalent iodine chemistry, but also enriches the oxidation chemistry of arylamines.

Hydrotalcite-like compounds (HTLcs): CoMAlCO3-HTLcs (M=Cu2+, Ni2+, Mn2+, Cr3+, Fe3+), were synthesized by coprecipitation and characterized with XRD and IR. The catalysis of these HTLcs and their calcined products were studied in the p-cresol oxidation, and the effects of the temperature of HTLcs calcination, the ratio of Co/Cu, different promoters, reaction temperatures and reaction times on reaction activities were investigated. It has been found that calcined HTLcs have higher activity than uncalcined samples and mechanical mixed oxides in this reaction. The best yield was obtained from the CoCuAlCO3-HTLc (Co/Cu/Al=3:1:1) calcined at 450 degrees C. A tentative reaction mechanism was also proposed. (C) 1998 Elsevier Science B.V.

Plenty of bacteria, yeasts, molds have been found in Chinese liquor pits. In order to investigate the applications of specifi c yeasts on ketone reduction, we screened some yeast strains in the Yeast Library of Chinese Liquor Pits in Chengdu Institute of Biology, Chinese Academy of Sciences, using f ive carbonyl compounds as potential substrates. The results indicated that the majority of the strains were capable of ketone reduction, and most of them obeyed the Prelog's rule. Some of the strains showed excellent stereo-selectivity, indicating high application potential in chiral drug intermediates production. For example, Williopsis sp. 2.045 transfered 3,5-bis(trif luoromethyl)-acetophenone into(S)-3,5-bis(trif luoromethyl)-1-phenethanol with over 99% yield and ee; Rhodotorula sp. 2.154 changed N-methyl-3-oxo-3-(thiophen-2-yl)propanamide into(S)-3-hydroxy-N-methyl-3-(thiophen-2-yl)propanamide with a yields of 95% and 99% ee. The results suggested that Chinese liquor pits contains lots of bioresources with high ketone reducing activity. It could be used as a targeted library in the screening of microbes with ketone reductase activity, which can highly improve the eff iciency of strain screening. Fig 6, Tab 6, Ref 24

A series of copolymers related in structure to the 1:2 alternating cyclocopolymer of divinyl ether and maleic anhydride (DIVEMA) have been shown to possess antitumor properties. The synthesis and structures of these copolymers are discussed, and their effectiveness as antitumor agents is presented. Certain of the copolymers have been prepared in controlled molecular weight ranges using chain transfer agents, and the resultant copolymers finally fractionated via use of solvent-nonsolvent systems. These samples of narrow molecular weight distribution have been evaluated for their antitumor properties and have been found to be quite effective.