Experimental and Theoretical Study on the Regioselective Radical Cyclization Reactions of 1-(o-Alkenylaryl)-2-amido-1-ketones for the Construction of Indeno[2,1-d][1,3]oxazin-9-ones.

A simple and efficient two-step method for the construction of novel 2,4,9a-trisubstituted-4a,9a-dihydroindeno[2,1-d][1,3]oxazin-9-ones has been developed. The NHC-catalyzed aza-benzoin reaction of o-alkenyl benzaldehydes with N-acylarylimines afforded 1-(o-alkenylaryl)-2-amido-2-aryl-1-ethanones, which underwent regioselective 5-exo-trig radical cyclization to furnish the three-ring-fused heterocyclic products, generally in good yields. The synthetic method displayed good tolerance toward the nature of substituents, substitution pattern, and steric hindrance of o-alkenyl benzaldehydes. Based on this method, the synthesis of unprecedented dihydrobenzo[6,7]indeno[2,1-d][1,3]oxazin-7-ones and dihydropyrido[2',3':3,4]cyclopenta[1,2-d][1,3]oxazin-9-ones has been achieved by employing o-alkenylnaphthaldehyde and o-alkenylnicotinaldehyde as substrates. The regioselectivity between 5-exo-trig and 6-endo-trig radical cyclization reactions of different 1-(o-alkenylaryl)-2-amido-2-aryl-1-ethanones were elucidated with DFT calculations.

3D Porous Ru-Doped NiCo-MOF Hollow Nanospheres for Boosting Oxygen Evolution Reaction Electrocatalysis.

Developing high-performance and cost-efficient catalysts toward oxygen evolution reaction (OER) is an important but daunting task due to the sluggish kinetics hindered by the four-electron transfer process. Herein, an advanced class of ultralow Ru-doped NiCo-MOF hollow porous nanospheres (denoted as Ru@NiCo-MOF HPNs) has been reported in this work. Benefiting from the high porosity and large surface area of the metal-organic frameworks (MOFs) and optimized electronic properties by Ru doping, the as-prepared Ru@NiCo-MOF HPNs exhibit superior performance for water oxidation with the overpotential of only 284 mV to reach a current density of 10 mA·cm-2 in alkaline electrolyte, as well as a small Tafel slope of 78.8 mV·dec-1, outperforming the NiCo-MOF HPNs (358 mV) and commercial RuO2 catalyst (326 mV). The incorporation of Ru in NiCo-MOF HPNs enables a stable OER activity for at least 39 h. Moreover, we have probed the interaction between the content of Ru and OER performance, impressively, Ru@NiCo-MOF HPNs with 13.5 atom % Ru doping (denoted as Ru@NiCo-MOF-4) exhibited the highest OER activity with the excellent mass activity of 310 mA·mg-1 at an overpotential of 284 mV. Besides, a two-electrode cell with Ru@NiCo-MOF-4 as the anode and commercial Pt/C catalyst as the cathode also demonstrated outstanding electrocatalytic overall water splitting performance with a cell potential of merely 1.57 V to deliver a current density of 10 mA·cm-2.

De novo synthesis of inherently chiral heteracalix[4]aromatics from enantioselective macrocyclization enabled by chiral phosphoric acid-catalyzed intramolecular SNAr reaction.

We report herein the synthesis of highly enantiopure inherently chiral N3,O-calix[2]arene[2]triazines from enantioselective macrocyclization enabled by chiral phosphoric acid-catalyzed intramolecular nucleophilic aromatic substitution reaction. In contrast to documented examples, the inherent chirality of the acquired compounds arises from one heteroatom difference in the linking positions of heteracalix[4](het)arenes.

Rh-Catalyzed C-H Alkynylation of Indole Derivatives with Silver(I)-Controlled Regiodivergence.

We have disclosed silver(I)-induced switching of regioselectivity in rhodium-catalyzed C-H alkynylation of indole derivatives with the help of a pivaloyl directing group by tuning C-H metalation modes. The judicious choice of AgOAc, Ag2O, and Ag2CO3 affords an array of C2-alkynylated indoles, C4-alkynylated indoles, and C2,C4-dialkynylated indoles, respectively. The synthetic utility of the alkyne fragment is demonstrated by derivatization into valuable indole-based compounds.

The role of agricultural mechanization services in reducing pesticide input: promoting sustainable agriculture and public health.

An increasing amount of pesticide input is posing a serious threat to the environment and public health. However, the quantitative analysis of the impact of agricultural mechanization services (AMS) on reducing pesticide input is not yet clear. In this study, the impact of AMS on pesticide input was estimated by using the Chinese Family Database and the endogenous switching regression model. Subsequently, testing the robustness of the model using the substitution variable method. The impact of AMS on different types of pesticides and the influence of farmers' choices of AMS on pesticide input under different terrain conditions and farm sizes were analyzed as well. The results demonstrate that AMS has a significant and negative impact on pesticide input, reducing pesticide expenditures by 56.08% for farmers who adopt AMS. For farmers who do not adopt AMS, adopting such services is assumed to reduce pesticide input by 14.97%. AMS can also reduce the use of insecticides and herbicides by over 54%. Compared to mountainous and hilly areas, AMS in plain areas increase the effectiveness of pesticide input reduction by 30.40%. Furthermore, small-scale farmers who adopt AMS can increase pesticide input reduction by 90 yuan/mu compared with large-scale farmers. Therefore, promoting the development of socialized AMS, strengthening AMS in mountainous and hilly areas, and expanding the scale of operation for small-scale farmers can help improve the effectiveness of pesticide input reduction. The results of this study can inform the development of strategies to reduce chemical pesticide use in agricultural soil.

3D Taraxacum-like porous Pd nanocages with Bi doping: High-performance non-Pt electrocatalysts for ethanol oxidation reaction.

Modifying the electronic structure and optimizing the geometric structure can expeditiously tune the electrocatalytic properties of catalysts, resulting in considerably enhanced electrocatalytic performance towards electrocatalytic oxidation of liquid fuels. We herein report a simple synthetic strategy to prepare Bi-doped 3D taraxacum-like Pd nanocages (NCs) composed of porous nanosheets, which possess high surface areas and strong synergistic effects. Notably, a trace of Bi diffuses into the lattice of Pd and increases the electronic effects of the surface of Pd, endowing PdBi-0.5 NCs/C with superior electrocatalytic performance towards ethanol oxidation reaction (EOR). The mass activity and specific activity of PdBi-0.5 NCs/C were 3494.8 mA mgPd-1 and 10.37 mA cm-2, being 4.08- and 4.82- fold enhancements as compared with commercial Pd/C, respectively. Moreover, the highly open porous 3D nanocages structure with rich active sites and defects can also facilitate the mass/electron transfer to favor the EOR kinetics.