We report a general protocol for the convergent synthesis of 1,4-dicarbonyl Z-alkenes form alkynes using α-diazo sulfonium triflate and water. The CO, CC, and C−H bonds are formed under mild conditions with a wide range of functional groups tolerated. The reaction exhibits excellent Z-selectivity and complete regioselectivity. The resulting 1,4-dicarbonyl Z-alkenes can smoothly undergo follow-up conversion to a variety of heteroaromatic scaffolds. Moreover, the reaction also provides a facile access to the corresponding deuterated Z-alkenes and deuterated heteroarenes with a high level of deuterium incorporation (90− 97% D-inc.) by directly using D 2 O, thus rendering the method highly valuable. The comprehensive mechanistic studies indicate that a free carbyne radical intermediate is formed via the photocatalytic single electron transfer process, and KH 2 PO 4 plays a crucial role in significant improvements on yield and selectivity based on density-functional theory calculations, providing a new direction for radical coupling reactions of diazo compounds.

Reported here is a concise total synthesis of (À)berkelic acid in eight linear steps. This synthesis features a Catellani reaction/oxa-Michael cascade for the construction of the isochroman scaffold, a one-pot deprotection/spiroacetalization operation for the formation of the tetracyclic core structure, and a late-stage Ni-catalyzed reductive coupling for the introduction of the lateral chain. Notably, four stereocenters are established from a single existing chiral center with excellent stereocontrol during the deprotection/spiroacetalization process. Stereocontrol of the intriguing deprotection/ spiroacetalization process is supported by DFT calculations.

Pt(II) and Au(III)-mediated intermolecular divergent annulations of benzofurazans and ynamides highlighted the N- to O-selectivity of tunable metal carbene intermediates. PtCl2 with a bulky phosphite ligand resulted in the specific synthesis of six-membered quinoxaline N-oxides and successfully suppressed the in-situ deoxygenation of N-oxides. On the other hand, an unique gold(III) catalyst (2,6-di-MeO-PyrAuCl3) led to the five-membered ring products, benzimidazoles. A broad scope of functional groups was well compatible, delivering better yields and selectivities in contrast to conventional gold(I) catalysts. The different behavior of presumed platinum(II) and gold(III) carbenes with respect to chemoselectivity was intensively examined by experiments and DFT calculations. A detailed mechanistic study, based on DFT calculations, revealed that the highly electrophilic carbocation-like gold(III) carbene triggers an oxophilic cyclization, followed by a cascade ring contraction and acyl migration. On the contrary, the Pt carbene species is less cationic, favoring the formation of the six-membered ring via N-attack.

A simple and general method for anti-selective hydrosulfonylation of unactivated alkynes with sulfonyl chlorides in the presence of a catalytic amount of phenanthroline-based Lewis base and (Me 3 Si) 3 SiH as the hydrogen atom donor has been developed. The protocol proceeds efficiently under mild and metal-free conditions, delivering a diverse set of (Z)-vinyl sulfones with high stereoselectivity. Additionally, the method displays excellent functional-group compatibility and can be applied to the late-stage modifications of complex drugs and their derivatives. Experimental and density functional theory studies unveiled that the key to the transformation's success is the employment of a phenanthroline-based Lewis base, which interacts with sulfonyl chlorides to form a halogen-bond complex that accelerates the cleavage of the S−Cl bonds of sulfonyl chlorides under the irradiation of visible light.

Replacing the planar hexacoordinate carbon in CX3M3+ species with the Be2 moiety leads to isoelectronic species with ultrashort Be–Be distances.

We present a detailed DFT mechanistic study on the first Ni-catalyzed direct carbonyl-Heck coupling of aryl triflates and aldehydes to afford ketones.

Insulators are important safety devices on high-voltage transmission lines. An insulator inspection system based on UAVs is widely used. Insulator defect detection is performed against two main engineering problems: 1. The scarcity of defect images, which leads to a network overfitting problem. 2. The small object detection, which is caused by the long aerial photography distance, and the low resolution of the insulator defect area pictures. In this study, firstly, the super-resolution reconstruction method is used to augment the dataset, which can not only solve the overfitting problem but also enrich the image texture features and pixel values of defect areas. Secondly, in the process of insulator defect detection, a two-stage cascading method is used. In the first stage, the rotated object detection algorithm is used to realize the object location of insulator strings, and then images of the identified insulators are cropped to reduce the proportion of the background area in defect images. In the second stage, YOLO v5 is used for the detection of insulator caps that are missing defects. The method proposed shows good detection effect on the self-built training set which contains only 85 images captured from real inspection environments. The method has practical industrial application value.

DFT calculations revealed that neutral polygons (E-Be2H3)n are the viable targets for realizing ultrashort metal–metal distances between main group metals.