Mechanochemistry as an emerging tool for molecular synthesis: what can it offer?

Mechanochemistry is becoming more widespread as a technique for molecular synthesis with new mechanochemical reactions being discovered at increasing frequency. Whilst mechanochemical methods are solvent free and can therefore lead to improved sustainability metrics, it is more likely that the significant differences between reaction outcomes, reaction selectivities and reduced reaction times will make it a technique of interest to synthetic chemists. Herein, we provide an overview of mechanochemistry reaction examples, with ‘direct’ comparators to solvent based reactions, which collectively seemingly show that solid state grinding can lead to reduced reaction times, different reaction outcomes in product selectivity and in some instances different reaction products, including products not accessible in solution

Mechanochemical activation of zinc and application to Negishi cross-coupling

A form independent activation of zinc, concomitant generation of organozinc species and engagement in a Negishi cross‐coupling reaction via mechanochemical methods is reported. The reported method exhibits a broad substrate scope for both C(sp3)–C(sp2) and C(sp2)–C(sp2) couplings and is tolerant to many important functional groups. The method may offer broad reaching opportunities for the in situ generation organometallic compounds from base metals and their concomitant engagement in synthetic reactions via mechanochemical methods

Rega-Net:Retina Gabor Attention for Deep Convolutional Neural Networks

Extensive research works demonstrate that the attention mechanism in convolutional neural networks (CNNs) effectively improves accuracy. But little works design attention mechanisms using large receptive fields. In this work, we propose a novel attention method named Rega-net to increase CNN accuracy by enlarging the receptive field. Inspired by the mechanism of the human retina, we design convolutional kernels to resemble the non-uniformly distributed structure of the human retina. Then, we sample variable-resolution values in the Gabor function distribution and fill these values in retina-like kernels. This distribution allows important features to be more visible in the center position of the receptive field. We further design an attention module including these retina-like kernels. Experiments demonstrate that our Rega-Net achieves 79.963\% top-1 accuracy on ImageNet-1K classification and 43.1\% mAP on COCO2017 object detection. The mAP of the Rega-Net increased by up to 3.5\% compared to baseline networks

TAM: A method for enrichment and depletion analysis of a microRNA category in a list of microRNAs

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are a class of important gene regulators. The number of identified miRNAs has been increasing dramatically in recent years. An emerging major challenge is the interpretation of the genome-scale miRNA datasets, including those derived from microarray and deep-sequencing. It is interesting and important to know the common rules or patterns behind a list of miRNAs, (i.e. the deregulated miRNAs resulted from an experiment of miRNA microarray or deep-sequencing).</p> <p>Results</p> <p>For the above purpose, this study presents a method and develops a tool (TAM) for annotations of meaningful human miRNAs categories. We first integrated miRNAs into various meaningful categories according to prior knowledge, such as miRNA family, miRNA cluster, miRNA function, miRNA associated diseases, and tissue specificity. Using TAM, given lists of miRNAs can be rapidly annotated and summarized according to the integrated miRNA categorical data. Moreover, given a list of miRNAs, TAM can be used to predict novel related miRNAs. Finally, we confirmed the usefulness and reliability of TAM by applying it to deregulated miRNAs in acute myocardial infarction (AMI) from two independent experiments.</p> <p>Conclusion</p> <p>TAM can efficiently identify meaningful categories for given miRNAs. In addition, TAM can be used to identify novel miRNA biomarkers. TAM tool, source codes, and miRNA category data are freely available at <url>http://cmbi.bjmu.edu.cn/tam</url>.</p

Robust Buchwald-Hartwig amination enabled by ball-milling

An operationally simple mechanochemical method for the Pd catalysed Buchwald–Hartwig amination of arylhalides with secondary amines has been developed using a Pd PEPPSI catalyst system. The system is demonstrated on 30 substrates and applied in the context of a target synthesis. Furthermore, the performance of the reaction under aerobic conditions has been probed under traditional solution and mechanochemical conditions, the observations are discussed herein

4-(4-Bromo­phen­yl)-2,6-diphenyl­pyridine

In the title compound, C23H16BrN, the three benzene rings show a disrotatory counter-rotating arrangement around the central pyridine ring and are twisted with respect to the pyridine ring with dihedral angles of 19.56 (13), 27.54 (13) and 30.51 (13)°

N-[2-(2-Hy­droxy­eth­oxy)pheneth­yl]phthalimide

The title compound, C18H17NO4, was obtained accidentally through acid-catalysed aromatization of a phthalimide-substituted 2-(1-hy­droxy­eth­yl)cyclo­hex-2-enone. It exhibits an intra­molecular O—H⋯Oc (c = carbonyl) hydrogen bond and forms a three-dimensional network structure via π–π stacking inter­actions between adjacent benzene rings (phthalimide-to-phenyl­ene and phthalimide-to-phthalimide), with centroid–centroid distances of 3.8262 (6) and 3.6245 (5) Å

Palladium(II)-Catalysed Aminocarbonylation of Terminal Alkynes for the Synthesis of 2-Ynamides: Addressing the Challenges of Solvents and Gas Mixtures

2‐Ynamides can be synthesised through Pd(II) catalysed oxidative carbonylation, utilising low catalyst loadings. A variety of alkynes and amines can be used to afford 2‐ynamides in high yields, whilst overcoming the drawbacks associated with previous oxidative methods, which rely on dangerous solvents and gas mixtures. The use of [NBu(4)]I allows the utilisation of the industrially recommended solvent ethyl acetate. O(2) can be used as the terminal oxidant, and the catalyst can operate under safer conditions with low O(2) concentrations