Search

A visible‐light‐promoted radical fluoroalkylation has been achieved through a three‐component reaction of fluoroalkyl reagents, isocyanides and water, affording fluoroalkyl‐substituted amides in good yields. This reaction involves the generation of the nitrilium cation by single‐electron reduction of the imidoyl radical and a subsequent nucleophilic attack by water. Mechanistic studies support the generation of the imidoyl radical through the capture of the fluoroalkyl‐substituted imidoyl radical species. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Isochromanone is the core structure of many bioactive compounds. Direct oxidation of isochromans is one of leading methods for the construction of isochromanones, while most established processes remain suffering from the use of environmentally unfriendly metal oxidants, harsh reaction conditions, and the difficulty in catalyst recycling and product separation. Herein, we report a convenient, cost‐effective, and green method for the synthesis of high‐value added isochromanones via isochroman oxidations with O2 by a novel heterogeneous vanadium cluster catalyst (Cat.1) under mild conditions. This reaction protocol demonstrates high catalytic activity with good catalyst recyclability and reusability for a wide scope of substrates. [ABSTRACT FROM AUTHOR]

A ruthenium(II)‐catalyzed hydroamination of allenoates with arylamines has been developed. This strategy provides an approach to synthesize E‐allylic amines in good yields with high atom‐economy and high levels of chemo‐, regio‐ and E‐selectivities with a broad substrate scope. [ABSTRACT FROM AUTHOR]

A visible‐light photoredox‐catalyzed three‐component difluoromethylative heteroarylation of unactivated alkenes is reported. This reaction provides a highly efficient and chemo‐selective method for the synthesis of difluoroalkyl‐containing quinoxalin‐2(1H)‐ones by the formation of two new C‐C bonds in single step from readily available starting materials under mild reaction conditions. This three‐component reaction displays a synthetic simplicity, broad substrate scope, and excellent functional group compatibilities. The preliminary mechanistic investigation implies that a radical process was responsible for this three‐component transformation. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A visible‐light‐induced tandem radical intramolecular cyclization/arylation of quinoxalin‐2(1H)‐ones with bromodifluoroacetamides is described. This protocol allows efficient access to a variety of valuable α,α‐difluoro‐γ‐lactam‐fused quinoxalin‐2(1H)‐ones in moderate to good yields under metal‐free, mild and redox neutral reaction conditions. This strategy is tolerant of various functional groups and a broad range of substrates. The mechanism experiments suggested an involvement of 5‐exo‐trig cyclization and a radical process in this transformation. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A visible‐light‐promoteded [3 + 2] cycloaddition reaction of 2H‐azirines with quinones has been developed under mild reaction conditions. The reaction provides a general and efficient strategy for the synthesis of the benzo[f]isoindole‐4,9‐diones scaffold via a tandem [3 + 2] cyclization/oxidative aromatization with molecular oxygen. Furthermore, preliminary studies for photocatalytic properties show that the benzo[f]isoindole‐4,9‐diones 3 can be used as photocatalysts in several organic transformations. [ABSTRACT FROM AUTHOR]

A novel base‐catalyzed intramolecular self‐cyclization reaction of o‐alkenylaryl isocyanides has been successfully developed. This reaction provides a general, efficient and atom‐economic method to access 4‐cyano‐3‐arylquinolines with broad scope of substrates and excellent functional group compatibilities. [ABSTRACT FROM AUTHOR]

This work reports the photocatalytic application of an anthraquinone‐containing polymeric photosensitizer (AQ‐PHEMA) in the visible light‐induced cross‐dehydrogenative‐coupling of N‐aryl tetrahydroisoquinolines with several nucleophiles, including nitromethane, 1‐methyl‐2‐alkyl ketone and dialkyl (aryl) phosphine oxide. The results revealed that the reaction could be catalyzed by AQ‐PHEMA efficiently to afford a series of 1‐substituted‐2‐aryl‐1,2,3,4‐tetrahydroisoquinolines in good to excellent yields with nice substrate tolerance under aerobic conditions at room temperature. The practical application potential was also showcased by a gram‐scale synthesis. More importantly, the utilization of AQ‐PHEMA as a heterogeneous photosensitizer also showed nice recyclability and reusability of the catalyst, whereas AQ‐PHEMA can be easily separated and reused for at least 8 times without significant loss of photocatalytic activity. [ABSTRACT FROM AUTHOR]

In this study, visible‐light‐induced [3+2] cyclization reactions of hydrazones with hypervalent iodine diazo reagents as diazomethyl radical precursors are reported. Mild reaction conditions, a broad substrate scope, and excellent functional group compatibility were observed. Furthermore, the synthetic utility was demonstrated by gram‐scale synthesis and elaboration to several value‐added products. This protocol broadens the scope of diazo chemistry, and is applicable to the late‐stage functionalization of natural products. [ABSTRACT FROM AUTHOR]

A visible‐light‐induced site selective C−H alkylation of heterocyclic N‐oxides with N‐hydroxyphthalimide esters was developed using Eosin Y as the photocatalyst in the presence of Cs2CO3 under redox‐neutral and mild conditions. Using N‐hydroxyphthalimide esters as the radical precursors, quinoline and pyridine N‐oxides were readily coupled with a wide range of primary, secondary, and tertiary radicals to afford the desired alkylated heterocyclic N‐oxides in moderated to excellent yields. Importantly, this reaction protocol also successfully demonstrated its applications for the construction of glycosyl or bioactive natural dehydroabietic acid containing heterocyclic N‐oxides, as well as the pharmaceutical and agrochemical active alkylated quinine‐based functional molecules (potential antimalarial drug). [ABSTRACT FROM AUTHOR]

A novel copper-catalyzed domino reaction between o-alkenyl aromatic isocyanides and diazo compounds has been developed under mild reaction conditions. Various o-alkenyl aromatic isocyanides were prepared from readily available reactants. The reaction provides a general and efficient method for the synthesis of pyrazolo[1,5-c]quinazolines by the formation of two rings and three new bonds in a single step from readily available acyclic starting materials. A mechanism involving a tandem (3+2) cyclization/elimination/intramolecular aza-addition sequence was proposed. [ABSTRACT FROM AUTHOR]

The anti-inflammatory activities of fucoxanthin, a marine carotenoid derived from the macroalgae and microalgae, have been demonstrated in the previous studies. However, the effect of fucoxanthin on ulcerative colitis (UC), an inflammatory bowel disease, was still unclear. In this study, we evaluated the in vivo anti-inflammatory effect of fucoxanthin on dextran sulfate sodium(DSS)-induced colitis in mice. Fucoxanthin at the doses of 50 and 100 mg/kg/day significantly protected against DSS-induced gradual loss of body weight, exhibited inhibitory effects on the DSS-induced increase of disease activity index and colon shortening. Moreover, fucoxanthin treatment resulted in a marked amelioration of the histological damage in the colon, and reduced the colonic PGE2 levels in colitic mice. In addition, the DSS-induced overexpressions of inflammation-related molecules including COX‐2 and NF-κB were significantly decreased in fucoxanthin-treated mice. These finding suggested that the use of fucoxanthin provides a new and attractive alternative to control UC. [ABSTRACT FROM AUTHOR]

In this study, a radical‐triggered cyclization of o‐alkenyl aromatic isocyanides prepared from accessible starting materials is developed. The reaction provides a general and efficient method for the synthesis of 4‐CN‐2‐CF3/CF2H‐containing quinolines under copper or visible‐light photoredox catalysis in a one‐pot synthetic procedure. This protocol demonstrates good to high yields, broad substrate scope, and good functional group tolerance. [ABSTRACT FROM AUTHOR]

A palladium(II)‐catalyzed acylation of 2‐phenylpyridine N‐oxides via ortho‐selective C−H activation at phenyl ring is developed using benzyl alcohols or α‐oxocarboxylic acids as the acylation reagents under mild conditions. The two reaction protocols exhibited complementary substrate scopes, and are tolerated to a variety of 2‐phenylpyridine N‐oxide substrates with high yield and selectivity. Mechanism studies indicated that this acylation reaction includes a radical process via acyl radical. [ABSTRACT FROM AUTHOR]

Homocoupling of weakly coordinating sulfoxonium ylides was accomplished via ruthenium (II) catalyzed C−H activation process. This strategy provides a convenient, efficient and step‐economic method to access 3‐substituted isocoumarins with good functional group tolerance. The sulfoxonium ylide acts both as the convenient aromatic substrate and the acylmethylation reagent in this transformation. Moreover, the products could be transformed to diverse valuable derivatives. [ABSTRACT FROM AUTHOR]

A novel base‐catalyzed 1,6‐conjugated addition of p‐QMs with diphenylphosphane oxide/phosphites has been developed. This reaction provides a highly efficient strategy for the construction of diarylmethyl phosphonate compounds in moderate to excellent yields with a broad substrate scope and good functional group tolerance under mild and metal‐free conditions. Moreover, the reaction can be carried out on a gram scale, which opens up the possibility for practical applications. [ABSTRACT FROM AUTHOR]

Palladium‐catalyzed remote meta‐selective C‐H functionalization of arylacetic acid has been developed using a pyrimidine template. This transformation is not only tolerated to a diverse range of arylacetic acid and alkene substrates but also applicable to the synthesis of pharmaceutically active ibuprofen derivatives. Moreover, the pyrimidine template was readily removable and recyclable under mild conditions. [ABSTRACT FROM AUTHOR]

Abstract: The transition‐metal‐free synthesis of β‐ketophosphine oxides from diphenylphosphorylallenes in the presence of pyrrolidine and silica gel has been developed under mild reaction conditions. This simple and efficient transformation tolerates a wide range of diphenylphosphorylallenes with different functional groups, and affords the desired products in moderate to excellent yields. [ABSTRACT FROM AUTHOR]

In this paper, a silicalite-1 modified HY zeolite (HY/silicalite-1) was prepared and applied as an efficient catalyst to promote the hydrolysis of microcrystalline cellulose to glucose in ionic liquid 1-ethyl-3-methylimidazolium chloride ([Emim]Cl). Scanning Electron Microscope reflects a core-shell morphology of HY/silicalite-1. When using HY/silicalite-1 as catalyst instead of non-modified HY, the glucose selectivity could be significantly improved, and the hydrolysis temperature could also be reduced to 110 °C. Under optimal conditions, 93.5% of total reducing sugar and 50.8% of glucose yield were obtained within 8 h of the reaction. The mechanism with respect to the hydrolysis of cellulose over HY/silicalite-1 was fully discussed. The improved sugar selectivity may due to reduced Lewis acidity of modified HY. Moreover, the reduced contact probability of sugar with the Lewis acid cites of catalyst caused by the outer silicalite-1 layer may also contribute to the good sugar selectivity. [ABSTRACT FROM AUTHOR]

A traceless organosilicon template-directed meta-selective-C–H alkenylation of phenols was realized with good yields and high selectivities. The template was readily removable through F−-promoted O–Si cleavage under extremely mild conditions or recyclable through a p-TSA catalyzed process. The product was successfully applied in the preparation of a series of meta-alkenylated aromatic compounds. [ABSTRACT FROM AUTHOR]

A cooperative CuBr2 and tert-butyl hydroperoxide (TBHP) system allowed for the highly stereoselective dibromination and bromohydroxylation reactions of (diphenylphosphoryl)allenes under mild (room temperature) and operationally simple conditions. These reactions selectively proceeded through either a dibromination or bromohydroxylation process and are characterized by their broad substrate scope (22 examples), their step economy, and ability to be carried out on a gram scale. This method offers a useful protocol to access allyl bromides and alcohols. Moreover, synthetic applications of the dibromination products include a Suzuki–Miyaura cross-coupling reaction and copper-catalyzed cascade process, which could also afford various important derivatives. [ABSTRACT FROM AUTHOR]

The palladium(II)-catalyzed hydroarylation of diphenylphosphorylallenes ( via 1,2-addition of the allenic double bond) with arylboronic acids in the presence of sodium hydroxide and oxygen is developed. The regioselectivities turn out to be well controlled, affording 2-aryl-3-(diphenylphosphinyl)alkenes as the only product. Moreover, the stereoselectivities for reactions of γ-substituted allenes can also be nicely controlled, resulting in the formation of Z-alkenes. The reaction shows high substituent loading capability and tolerance of various substituents. A mechanism, including transmetalation of arylboronic acid with palladium halides, insertion of the 1,2-allenic double bond to the Pd−Ar bond, and protonation to afford the final hydroarylation product is proposed. [ABSTRACT FROM AUTHOR]

Mo8O264− based organic polyoxomolybdate salts of general formula [Hmim]4Mo8O26 (Hmim = 1-hexyl-3-methylimidazolium), [Dhmim]4Mo8O26 (Dhmim = 1,2-dimethyl-3-hexylimidazolium) and [Hpy]4Mo8O26·H2O (Hpy = 1-hexylpyridinium) have been prepared and characterized. These compounds were applied as catalysts for olefin epoxidation using hydrogen peroxide (H2O2) as oxidant in CH3CN. The polyoxomolybdate salts exhibit excellent catalytic performance and are also self-separating, a great advantage for catalyst recycling. The catalysts can be reused for at least 10 runs without significant loss of activity. [ABSTRACT FROM AUTHOR]

Imidazolium-based ionic liquids that contain perrhenate anions are very efficient reaction media for the epoxidation of olefins with H2O2 as an oxidant, thus affording cyclooctene in almost quantitative yields. The mechanism of this reaction does not follow the usual pathway through peroxo complexes, as is the case with long-known molecular transition-metal catalysts. By using in situ Raman, FTIR, and NMR spectroscopy and DFT calculations, we have shown that the formation of hydrogen bonds between the oxidant and perrhenate activates the oxidant, thereby leading to the transfer of an oxygen atom onto the olefin demonstrating the special features of an ionic liquid as a reaction environment. The influence of the imidazolium cation and the oxidant (aqueous H2O2, urea hydrogen peroxide, and tert-butyl hydrogen peroxide) on the efficiency of the epoxidation of cis-cyclooctene were examined. Other olefinic substrates were also used in this study and they exhibited good yields of the corresponding epoxides. This report shows the potential of using simple complexes or salts for the activation of hydrogen peroxide, owing to the interactions between the solvent medium and the active complex. [ABSTRACT FROM AUTHOR]

Aims Neuregulin-1 (NRG-1) plays a critical role in the adaptation of the heart to injury, inhibiting apoptosis and inducing cardiomyocyte proliferation. We have shown previously that rhNRG-1 improves cardiac function and survival in animal models of cardiomyopathy. Here we report the first human study aimed at exploring the acute and chronic haemodynamic responses to recombinant human NRG-1 (beta2a isoform; rhNRG-1) in patients with stable chronic heart failure (CHF). Methods and results Fifteen patients (age, 60 ± 2; NYHA II:III, 9:6; left ventricular ejection fraction (LVEF) <40%) on optimal medical therapy for CHF, received a rhNRG-1 infusion daily for 11 days. Acute and chronic haemodynamic, structural and biochemical effects were determined by serial right heart catheterization, cardiac magnetic resonance (CMR), echocardiography and measurement of neurohumoral indices. Acutely, cardiac output increased by 30% during a 6 h rhNRG-1 infusion (P < 0.01). Pulmonary artery wedge pressure and systemic vascular resistance decreased 30 and 20%, respectively, at 2 h (P < 0.01). A 47% reduction in serum noradrenaline, a 55% reduction in serum aldosterone and a 3.6-fold increase in N-terminal prohormone brain natriuretic peptide levels were concurrently observed (P < 0.001). These acute haemodynamic effects were sustained, as demonstrated by the 12% increase in LVEF from 32.2 ± 2.0% (baseline) to 36.1 ± 2.3% (mean ± SE, P < 0.001) at 12 weeks. The therapy was well tolerated. Conclusion rhNRG-1 appears to produce favourable acute and chronic haemodynamic effects in patients with stable CHF on optimal medical therapy. Randomized controlled trials of rhNRG-1 in cardiac disease are thus warranted. Clinical Trial Registration Information The trial was registered with the Australian New Zealand Clinical Trials Registry, anzctr.org.au Identifier: ACTRN12607000330448. [ABSTRACT FROM AUTHOR]

Dioxomolybdenum(VI) complexes with the general formula [MoO2Cl2L2] (L2=3,3′-dimethyl-2,2′-bipyridine, 5,5′-dimethyl-2,2′-bipyridine, 6,6′-dimethyl-2,2′-bipyridine, 4,4′-dibromo-2,2′-bipyridine, 5,5′-dibromo-2,2′-bipyridine, 5,5′-diamino-2,2′-bipyridine; 5,5′-dinitro-2,2′-bipyridine; 5,5′-di-ethoxycarbonyl-2,2′-bipyridine; 6-phenyl-2,2′-bipyridine; 2,2′:6′,2″-terpyridine) have been prepared and characterised. [MoO2Cl2(5,5′-di-ethoxycarbonyl-2,2′-bipyridine)] has been examined by single crystal X-ray analysis. The complexes were applied as homogenous catalysts for the epoxidation of cyclooctene with tert-butyl hydroperoxide (TBHP) as oxidising agent. The new compounds show an overall high activity and are highly selective catalysts in the epoxidation of cyclooctene. The stability of the complexes and differences in the catalytic activity can be clearly attributed to electronic contributions of the functional groups on bipyridine ligands and to steric restrictions. DFT calculations have assisted in a better understanding of the stability of the complexes and are in agreement with experiment. The influence of the terminal oxo ligands and the Lewis base ligands on the Mo center keep the compounds on quite a stable level of electron density. [ABSTRACT FROM AUTHOR]