Aryl boronic acid-controlled divergent ring-contraction and ring-opening/isomerization reaction of tert-cyclobutanols enabled by nickel catalysis.

In this work, we wish to present a nickel-catalyzed divergent ring-contraction and ring-opening/isomerization reaction of tert-cyclobutanols. The key to control these two different reaction pathways is to choose appropriate boronic acid, where the use of phenylboronic acid and pyrimidin-5-ylboronic acid enables a ring-contraction and ring-opening reaction/isomerization, respectively. Both cyclopropyl aryl methanones and 1-aryl butan-1-ones could be selectively obtained.

Nickel-catalyzed divergent formylation and carboxylation of aryl halides with isocyanides.

Herein, we describe a nickel-catalyzed divergent formylation and carboxylation reaction of aryl halides with isocyanides. A rich array of aromatic aldehydes and carboxylic acids can be, respectively, accessed in moderate to good yields. Some sensitive functional groups such as hydroxyl, iodine, cyano, and indolyl are fairly tolerant of nickel catalysis. In the carboxylation reactions, the combination of isocyanide and H2O is first employed as a promising carbonyl surrogate instead of gaseous CO and CO2.

Potentially toxic elements in smoke particles and residual ashes by biomass combustion from Huangshi National Mine Park, China.

This paper investigates the fractional and spatial distribution characteristics of potentially toxic elements (PTEs) in smoke particles and residual ashes from mine-park-biomass combustion. It then evaluates the consequential potential environment risk by using a Geo-accumulation index and Nemerow pollution index methods. Biomass combustibles are comprised of Camphor leaves (CL), Camphor dead-branch (CB), Ramie (RA), Miscanthus sinensis (MS), and Dryopteris (DR). The results show that the products of combustion contain PTEs, As, Cr, Cu, and Zn, etc. Among them, the content of As, Cr, Cu, Pb elements in smoke particles of CB was higher than other combustibles. Moreover, Cr, Mn, Ni, and Pb in residual ashes of CL were higher than others. The proportion of acid-soluble and reducible fraction of As in residual ash was higher, while Cr existed mainly in the oxidizable and residual fraction. Besides, the available state of As gradually decreased from 74% (400 °C) to 41% (800 °C), indicating that the increase of temperature significantly reduced the bioavailability of As. Meanwhile, with the increase of temperature, the concentration of PTEs in smoke particles decreased and PTEs in residual ashes increased in different degrees. The risk evaluation results indicate that PTEs may cause moderate or higher levels of contamination. The overall contamination level of PTEs in the residual ashes of CB was higher than that of other plant. The results show in this study would contribute to understanding the environmental risks of wildfire and prescribed burning in PTEs-contaminated areas.

P/N-Heteroleptic Cu(I)-Photosensitizer-Catalyzed [3 + 2] Regiospecific Annulation of Aminocyclopropanes and Functionalized Alkynes.

We report here a regiospecific [3 + 2] annulation between aminocyclopropanes and various functionalized alkynes enabled by a P/N-heteroleptic Cu(I) photosensitizer under photoredox catalysis conditions. Thus, a divergent construction of 3-aminocyclopentene derivatives including methylsulfonyl-, arylsulfonyl-, chloro-, ester-, and trifluoromethyl-functionalized aminocyclopentenes could be achieved with advantages of high regioselectivity, broad substrate compatibility, and mild and environmentally benign reaction conditions.

Nickel-catalyzed cascade hydrosilylation/cyclization of 1,7-enynes leading to silyl-containing quinolinones.

We herein describe a nickel-catalyzed cascade hydrosilylation/cyclization reaction of 1,7-enynes with bulky triphenylsilane. A series of silyl-containing quinolinone derivatives are obtained in good to excellent yields under mild reaction conditions. This reaction also features excellent chemoselectivity, broad functional group tolerance, and gram-scale synthesis.

Nickel-catalyzed cyanation reaction of aryl/alkenyl halides with alkyl isocyanides.

We herein describe a nickel-catalyzed cyanation reaction of aryl/alkenyl halides with alkyl isocyanides. Both aryl/alkenyl iodines and bromides were found to be competent electrophiles that reacted with alkyl isocyanides, affording nitrile compounds in moderate to good yields. A range of functional groups including halogens as well as hydroxyl, formyl, and acetamino groups were fairly compatible with the nickel catalysis. This protocol featured broad functional group tolerance, simple reaction conditions, and gram-scale synthesis.

Nickel-Catalyzed Arylation/Alkenylation of tert-Cyclobutanols with Aryl/Alkenyl Triflates via a C-C Bond Cleavage.

Herein, we first present a nickel-catalyzed arylation and alkenylation of tert-cyclobutanols with aryl/alkenyl triflates via a C-C bond cleavage. An array of γ-substituted ketones was obtained in moderate-to-good yields, thus featuring earth-abundant nickel catalysis, broad substrate scope, and simple reaction conditions. Preliminary mechanistic experiments indicated that ß-carbon elimination pathways might be involved in the catalytic cycle.

Nickel-catalyzed remote hydrosilylation of unconjugated enones with bulky triphenylsilane.

Herein we describe a nickel-catalyzed remote hydrosilylation of unconjugated enones with bulky triphenylsilane. A range of Z-silyl enol ethers are obtained as major isomers due to the process of nickel triggered alkene isomerization. Notably, some specific alkyl silyl enol ethers can be prepared from this protocol, which are not easily accessed by the traditional strategy using a strong base and chlorosilane. This reaction features 100% atom economy, simple reaction conditions, and good yields.

NHC-catalyzed Truce-Smiles rearrangement of N-aryl methacrylamides for the synthesis of trans-cinnamides.

Herein we describe a NHC-catalyzed Truce-Smiles rearrangement of N-aryl methacrylamides which enables the cleavage of an inert aryl C-N bond. A range of trans-cinnamides could be obtained by the direct construction of a C(aryl)-C(alkenyl) bond and functional groups such as Br, Cl, CN, and pyridinyl are compatible with NHC catalysis. The reaction features high atom-economy, transition-metal free catalysis, and easily available substrates.

Bifunctional Phosphine Ligand-Enabled Gold(I)-Catalyzed O-Nucleophilic Addition of N-Hydroxybenzo[1,2,3]-triazin-4(3H)-ones to Alkynes Followed by [3,3]-Rearrangement: Simultaneous Formation of C-O and C-N Bonds.

We describe a gold (I)-catalyzed tandem O-nucleophilic addition/[3,3]-rearrangement reaction of N-hydroxybenzo[1,2,3]-triazin-4(3H)-ones with alkynes enabled by a biphenyl-2-yl phosphine ligand featuring a pendant amide moiety (L1). A variety of 1-(2-oxo-2-arylethyl)benzo [d][1,2,3]triazin-4(1H)-one derivatives were synthesized in good to excellent yields. The present protocol gives a rare example of simultaneous formation of C-O and C-N bonds in the gold(I)-catalyzed [3,3]-sigmatropic rearrangements.

Inert C-H Bond Transformations Enabled by Organometallic Manganese Catalysis.

Traditional organic synthesis relies heavily on the transformations of various preinstalled functional groups, such as cross-coupling reactions using organohalides and organometallic reagents. The strategy of C-H activation enables the direct formation of C-C/C-X (X = heteroatom) bonds from inert C-H bonds, which can enhance the atom- and step-economy of organic synthesis. To date, precious metals have overwhelmingly dominated the C-H activation field; however, the rarity and high cost of these metals necessitate the development of more sustainable catalysts. In this regard, catalysts based on manganese are highly desirable owing to the abundant reserve of manganese in the earth's crust and its economic benefits, low toxicity, and potentially unique reactivity. Although the first stoichiometric manganese-mediated C-H activation reaction was reported as early as 1970, manganese-catalyzed C-H activation reactions are largely underdeveloped. How to construct an efficient catalytic cycle for manganese in C-H activation reactions remains as a key issue to be addressed. In this Account, we summarize our recent advances in the manganese-catalyzed transformations of inert C-H bonds. To overcome the challenges associated with building manganese-based catalytic cycles, we developed two novel strategies, namely, synergy between manganese catalysts and bases and between manganese catalysts (with or w/o bases) and acids. By implementing the former strategy, we developed cooperative manganese/base catalytic systems that facilitate a new mode of C-H bond activation by manganese via a redox-neutral base-assisted deprotonation mechanism. As such, the requirement for the tedious preparation of MnR(CO)5 complexes (R = Me, Bn, Ph) in stoichiometric reactions was eliminated, and a series of manganese-catalyzed C-H activation reactions of arenes with various reaction partners having C≡C and C═C bonds were achieved. Through the latter strategy of synergy between manganese catalysts (with or w/o bases) and acids, we disclosed a "dual activation" mode for performing manganese-catalyzed C-H bond transformations, that is, merging C-H activation by manganese catalysts and C-X multiple bond activation by Lewis acids. Consequently, the scope of C-H substrates could be expanded to include challenging ketones and olefinic C-H compounds. Additionally, the range of reaction partners could be significantly broadened to include those bearing more polarized C═O, C═N, and C≡N bonds such as aldehydes, imines, and nitriles. Remarkably, the innate reactivity of different C-H bonds in ketones could be reversed by manganese catalysis, and the reactions could even be carried out at room temperature. Our findings provide guiding information for the future development of manganese-catalyzed C-H activation reactions and beyond. Related important contributions from other groups are mentioned, and the remaining challenges and future perspective in this emerging area are also presented.

Diboron-Assisted Copper-Catalyzed Z-Selective Semihydrogenation of Alkynes Using Ethanol as a Hydrogen Donor.

We herein describe a B2Pin2-assisted copper-catalyzed semihydrogenation of alkynes. A variety of alkenes were obtained in good to excellent yields with Z-selectivity under mild reaction conditions. Mechanistic studies indicated that a transfer hydrogenation process was involved and ethanol acted as both a solvent and a hydrogen donor in this reaction. The present protocol enabled convenient synthesis of deuterium-substituted Z-alkenes such as Z-Combretastain A4- d2 in a high deuteration ratio by using readily available ethanol- d1 as the deuterium source.

I2O5-Mediated 1,5-Cyclization of Aryldiynes with H2O: A Way To Access 3-Acyl-1-indenone Derivatives.

A facile I2O5-mediated 1,5-cyclization of aryldiynes with H2O has been successfully developed, leading to a broad range of substituted 3-acyl-1-indenones in moderate to excellent yields. The protocol has advantages of a metal-free process, mild reaction conditions, simple operation, and broad functional group tolerance. In the reaction, H2O is used as both a cosolvent and an oxygen source.

I2O5-Mediated Iodocyclization Cascade of N-(1-Arylallyl)pyridine-2-amines with Concomitant C═C Bond Cleavage: A Synthesis of 3-Iodoimidazo[1,2- a]pyridines.

A facile method for the synthesis of 3-iodoimidazo[1,2- a]pyridines has been successfully developed involving an I2O5-mediated iodocyclization cascade of N-(1-arylallyl)pyridin-2-amines with concomitant C═C bond cleavage. Preliminary mechanistic studies reveal that this protocol might undergo an oxidative cyclization/decarboxylation/iodination sequence in which I2O5 is used as both an oxidant and an iodine source. The present protocol has advantages of wide substrate scope, simple operation, and metal-free conditions.

Copper-catalyzed three-component reaction of N-heteroaryl aldehydes, nitriles, and water.

An efficient and straightforward method for the synthesis of N-heteroaroyl imides has been successfully developed involving a copper-catalyzed radical-triggered three-component reaction of N-heteroaryl aldehydes, nitriles, and water. Mechanistic studies indicate that the reaction may undergo a radical-triggered Ritter-type reaction in which water serves as the oxygen source for the formation of the C-O bond. The reaction has advantages such as a broad substrate scope for the N-heteroaryl aldehydes, atom economy, and simple operation.

Manganese-Catalyzed Redox-Neutral C-H Olefination of Ketones with Unactivated Alkenes.

Since 1987, stoichiometric cyclomanganation of ketones and subsequent reactions with olefins in the presence of either palladium salts or trimethylamine N-oxide (Me3 N+ O- ) have been reported, but the catalytic versions remain untouched so far. Herein, the first manganese-catalyzed redox-neutral C-H olefination of ketones with unactivated alkenes is described, and shows a distinct reactivity with its parent stoichimetric reactions. Remarkably, mechanistic experiments and DFT calculations uncovers a unique concerted bis-metalation deprotonation (CBMD) mechanism of the Mn-Zn-enabled C-H bond activation.

Copper-catalyzed three-component cascade reaction of alkynes, sulfonyl azides and simple aldehydes/ketones.

A copper-catalyzed dimethylzinc-promoted three-component cascade reaction of alkynes, sulfonyl azides, and simple aldehydes or ketones is described. Polysubstituted olefins were thus constructed expeditiously in a one-pot procedure under mild conditions.

Manganese-Catalyzed Direct Nucleophilic C(sp(2))-H Addition to Aldehydes and Nitriles.

Herein, a manganese-catalyzed nucleophilic addition of inert C(sp(2))-H bonds to aldehydes and nitriles is disclosed by virtue of a dual activation strategy. The reactions feature mild reaction conditions, excellent regio- and stereoselectivity, and a wide substrate scope, which includes both aromatic and olefinic C-H bonds, as well as a large variety of aldehydes and nitriles. Moreover, mechanistic studies shed light on possible catalytic cycles.

Prediction of miRNAs and diseases association based on sparse autoencoder and MLP.

Introduction: MicroRNAs (miRNAs) are small and non-coding RNA molecules which have multiple important regulatory roles within cells. With the deepening research on miRNAs, more and more researches show that the abnormal expression of miRNAs is closely related to various diseases. The relationship between miRNAs and diseases is crucial for discovering the pathogenesis of diseases and exploring new treatment methods. Methods: Therefore, we propose a new sparse autoencoder and MLP method (SPALP) to predict the association between miRNAs and diseases. In this study, we adopt advanced deep learning technologies, including sparse autoencoder and multi-layer perceptron (MLP), to improve the accuracy of predicting miRNA-disease associations. Firstly, the SPALP model uses a sparse autoencoder to perform feature learning and extract the initial features of miRNAs and diseases separately, obtaining the latent features of miRNAs and diseases. Then, the latent features combine miRNAs functional similarity data with diseases semantic similarity data to construct comprehensive miRNAs-diseases datasets. Subsequently, the MLP model can predict the unknown association among miRNAs and diseases. Result: To verify the performance of our model, we set up several comparative experiments. The experimental results show that, compared with traditional methods and other deep learning prediction methods, our method has significantly improved the accuracy of predicting miRNAs-disease associations, with 94.61% accuracy and 0.9859 AUC value. Finally, we conducted case study of SPALP model. We predicted the top 30 miRNAs that might be related to Lupus Erythematosus, Ecute Myeloid Leukemia, Cardiovascular, Stroke, Diabetes Mellitus five elderly diseases and validated that 27, 29, 29, 30, and 30 of the top 30 are indeed associated. Discussion: The SPALP approach introduced in this study is adept at forecasting the links between miRNAs and diseases, addressing the complexities of analyzing extensive bioinformatics datasets and enriching the comprehension contribution to disease progression of miRNAs.

Nickel-Catalyzed Cross-Coupling Reaction of Aryl Bromides/Nitriles with Imidazolium Salts Involving Inert C-N Bond Cleavage.

We herein present a nickel-catalyzed cross-coupling reaction of aryl halides and nitriles with imidazolium salts. A series of 2-arylated imidazoles could be obtained in moderate to good yields through inert C-N bond cleavage. The imidazolium salt in this reaction acts as both a coupling partner and N-heterocyclic carbene (NHC) ligand precursor. Mechanistic studies reveal that consecutive steps of migratory insertion of the NHC into the aryl C-Ni bond and ß-C elimination might be involved in the proposed reaction mechanism.