Novel access to 1,4-benzodiazepin-2-ones via the Buchwald reaction and application to the synthesis of novel heterocyclics

A new two step strategy for the preparation of 1,4-benzodiazepin-2-ones has been developed starting from the 2-halogenobenzophenone under Buchwald conditions (Pd(OAc)₂, XantPhos, Cs₂CO₃, dioxane 100 °C). This strategy has been extended to two 2-halogeno-3-benzoyl-azines (pyridines, pyridazines).     

Confined Ultrathin Pd‐Ce Nanowires with Outstanding Moisture and SO2 Tolerance in Methane Combustion

An efficient strategy (enhanced metal oxide interaction and core–shell confinement to inhibit the sintering of noble metal) is presented confined ultrathin Pd‐CeO_x nanowire (2.4 nm) catalysts for methane combustion, which enable CH₄ total oxidation at a low temperature of 350 °C, much lower than that of a commercial Pd/Al₂O₃ catalyst (425 °C). Importantly, unexpected stability was observed even under harsh conditions (800 °C, water vapor, and SO₂), owing to the confinement and shielding effect of the porous silica shell together with the promotion of CeO₂. Pd‐CeO_x solid solution nanowires (Pd‐Ce NW) as cores and porous silica as shells (Pd‐CeNW@SiO₂) were rationally prepared by a facile and direct self‐assembly strategy for the first time. This strategy is expected to inspire more active and stable catalysts for use under severe conditions (vehicle emissions control, reforming, and water–gas shift reaction).     

Synthesis of dihydrobenzoxazine pyrrolidone spirocyclic compounds

A simple and efficient synthetic strategy for the preparation of dihydrobenzoxazine spirocyclic compounds was reported via the cycloaddition reaction of o-succinimide-substituted benzaldehyde with nitrobenzene. The reactions can be conducted under very mild reaction conditions (room temperature) using 10?mol% of Cs₂CO₃ as catalyst. A series of dihydrobenzoxazine pyrrolidone spirocyclic compounds were afforded in moderate to good yields. This strategy provides a new direction for the synthesis and study on biological activities of dihydrobenzoxazine pyrrolidone spirocyclic compounds.     

Microwave-assisted controllable synthesis of 2-acylbenzothiazoles and bibenzo[b][1,4]thiazines from aryl methyl ketones and disulfanediyldianilines

A condition-controlled strategy for selectively synthesis of 2-acylbenzothiazoles and bibenzo[b][1,4]thiazines from aryl methyl ketones and disulfanediyldianilines was realized using I₂/DMSO or I₂/MeCN systems, respectively. The desired products were synthesized in only 15 min with moderate to excellent yields (50%-90%) under microwave-assisted, metal-free conditions. The strategy provides a great advantage for selective synthetic applications in the efficient synthesis of benzothiazoles and bibenzothiazines heterocycle compounds.     

Enhancement of Visible-Light-Driven Hydrogen Evolution Activity of 2D π-Conjugated Bipyridine-Based Covalent Organic Frameworks via Post-Protonation

Photocatalytic hydrogen (H₂) evolution represents a promising and sustainable technology. Covalent organic frameworks (COFs)-based photocatalysts have received growing attention. A 2D fully conjugated ethylene-linked COF (BTT-BPy-COF) was fabricated with a dedicated designed active site. The introduced bipyridine sites enable a facile post-protonation strategy to fine-tune the actives sites, which results in a largely improved charge-separation efficiency and increased hydrophilicity in the pore channels synergically. After modulating the degree of protonation, the optimal BTT-BPy-PCOF exhibits a remarkable H₂ evolution rate of 15.8 mmol g⁻¹ h⁻¹ under visible light, which surpasses the biphenyl-based COF 6 times. By using different types of acids, the post-protonation is proved to be a potential universal strategy for promoting photocatalytic H₂ evolution. This strategy would provide important guidance for the design of highly efficient organic semiconductor photocatalysts.     

N‐Doped Yellow TiO2 Hollow Sphere‐Mediated Visible‐Light‐Driven Efficient Esterification of Alcohol and N‐Hydroxyimides to Active Esters

Herein we report a simple synthetic protocol for N‐doped yellow TiO₂ (N‐TiO₂) hollow spheres as an efficient visible‐light‐active photocatalyst using aqueous titanium peroxocarbonate complex (TPCC) solution as precursor and NH₄OH. In the developed strategy, the ammonium ion of TPCC and NH₄OH acts as nitrogen source and structure‐directing agent. The synthesized N‐TiO₂ hollow spheres are capable of promoting the synthesis of active esters of N‐hydroxyimide and alcohol through simultaneous selective oxidation of alcohol to aldehyde followed by cross‐dehydrogenative coupling (CDC) under ambient conditions upon irradiation of visible light. It is possible to develop a novel and cost‐effective one‐pot strategy for the synthesis of important esters and amides on gram scale using the developed strategy. The catalytic activity of N‐TiO₂ hollow spheres is much superior to that of other reported N‐TiO₂ samples as well as TiO₂ with varying morphology.     

Facile synthesis of 3-substituted indoles containing highly polarized double bonds

In this paper, an effective procedure is described for the synthesis of novel indoles containing highly polarized double bonds. The strategy involves the preparation of (indolylmethyl)malononitriles via the one-pot three-component reaction of an aldehyde, malononitrile and indole in the presence of Zn(OAc)₂/NaOAc under silent and ultrasonic conditions. The reaction further proceeds through oxidative elimination under solvent-free conditions in the presence of Ca(OCl)₂ to furnish indolylacrylonitriles in high yields and short reaction times.     

Acceptorless Photocatalytic Dehydrogenation of Furfuryl Alcohol (FOL) to Furfural (FAL) and Furoic Acid (FA) over Ti3C2Tx/CdS under Visible Light

Acceptorless photocatalytic dehydrogenation is not only a promising alternative to photocatalytic water splitting for hydrogen generation but also provides a green and sustainable strategy for the synthesis of value-added organic compounds. In this work, Ti₃C₂T_x/CdS nanocomposites were obtained by self-assembly of hexagonal CdS in the presence of preformed Ti₃C₂T_x nanosheets, which serves as a photocatalyst for acceptorless dehydrogenation of biomass-derived furfuryl alcohol (FOL) to furfural (FAL) and furoic acid (FA) in neutral and alkaline medium respectively, with simultaneous generation of stoichiometric hydrogen under visible light. Ti₃C₂T_x MXene acts as an efficient cocatalyst for the photocatalytic dehydrogenation of FOL over CdS, with an optimum performance achieved over 0.50 wt% Ti₃C₂T_x/CdS nanocomposite. This study provides an economic and sustainable strategy for the simultaneous valorization of biomass-derived FOL to produce FAL and FA as well as the production of clean energy hydrogen under mild condition based on noble metal-free semiconductor-based photocatalysts.     

A novel O-fucosylation strategy preactivated by (p-Tol)2SO/Tf2O and its application for the synthesis of Lewis blood group antigen Lewisa

Based on a preactivation strategy using (p-Tol)₂SO/Tf₂O, a new O-fucosylation method with thioglycoside as donor under mild conditions was reported. High yields and excellent α-stereoselectivities of the fucosylation were obtained with secondary sugar alcohol as acceptors. Moreover, the novel fucosylation strategy was successfully applied to the synthesis of an important Lewis blood group antigen Lewis^a, which was obtained in nine linear steps with 27% overall yield.     

B(C6F5)3-catalyzed oxidative deamination/cyclization cascade reaction of benzylamines and ketones for the synthesis of 2,4,6-triarylpyridines

The B(C₆F₅)₃-catalyzed oxidative deamination/cyclization cascade reaction of benzylamines and ketones for the construction of 2,4,6-triarylpyridines under metal-/solvent-free conditions has been successfully achieved. The advantages of this strategy include good functional group tolerance, low catalyst loading and high yields.     

Vanadium Catalyst for C- and S-Alkylation of Benzhydrols in Water: An Experimental Study and Green Metrics Evaluation

A strategy for the vanadium-catalyzed dehydrative C- and S-alkylation by nucleophilic substitution of benzhydrols with arenes and thiols is reported. The alkylation was achieved with the divanadium oxoperoxo complex [K₃(V⁺⁵)₂(O₂²⁻⁾₄(O²⁻)₂(μ-OH)] in water under air. The newly developed transformation could accommodate a broad substrate scope, including (hetero)arenes and thiols (34 examples). Both the symmetrical and unsymmetrical benzhydrols furnished excellent yields of the alkylated product under mild reaction conditions. The scope of this strategy was further extended to synthesize bis-benzylated arenes (poly-arylated products) in high yields and regioselectivities. The green metrics determination of all the alkylated products suggests the technical and environmental benefits of the present protocol. The longevity experiment reveals the catalytic activity was maintained over seven cycles. To understand the mechanism of the present reaction, spectroscopic and kinetic studies were undertaken. This simple protocol, which affords the desired products with water as the by-product, can be achieved under mild conditions without needing a base or other additives.     

Thiocyanation of Allylic Alcohols Promoted by Trifluoroacetic Acid

A rapid and efficient acid-promoted strategy to access allylic thiocyanates using allylic alcohols as substrates and easily-available NH₄SCN as the thiocyanate source is presented under metal- and oxidant-free conditions. Through screening of various kinds of acids, organic and strong trifluoroacetic acid (TFA) was found most effective. Testing of substrates showed that the strategy has remarkable functional group tolerance. A possible mechanism is provided, and the gram-scale experiment demonstrate that this novel protocol has potential industrial application value.     

Direct conversion of glucose and cellulose to 5-hydroxymethylfurfural in ionic liquid under microwave irradiation

An efficient strategy for CrCl₃-mediated production of 5-hydroxymethylfurfural (HMF) in ca. 60% and 90% isolated yields from cellulose and glucose, respectively, in ionic liquid under microwave irradiation is presented.     

首例含4, 4'-联吡啶和乙酸锌的光致变色化合物

采用一种新方法得到一维配位聚合物[Zn(CH₃COO)₂(4,4'-bipy)]_n(1)。配合物1的晶体结构和荧光性质已经有详细报道,但光致变色性质还没有相关的研究工作发表。通过研究化合物1在光照前后的紫外吸收光谱和顺磁共振谱,表明化合物1具有电子转移光致变色性能。实验结果验证了我们提出的利用非光致变色单元设计电子转移光致变色材料的新方法是有效可行的。     

Visible-light-promoted oxidative difunctionalization of alkenes with sulfonyl chlorides to access β-keto sulfones under aerobic conditions

A mild, practical and efficient strategy to prepare β-keto sulfones has been developed by visible light promoted reactions. This reaction involves Ir(ppy)₂(dtbbpy)PF₆ catalyzed direct funcationalization of alkenes with sulfonyl chlorides under mild conditions. Air was used as oxidant without any additives. The transformation affords the corresponding products in moderate to high yields.     

Fluorinated Vinyl Sulfonium Salts and Their Synthetic Utilization

The fluorinated building block strategy and the direct fluorination strategy are of great importance for the synthesis of new fluorinated molecules. These strategies complement each other and can be combined to develop a new methodology for the construction of a wide variety of fascinating organofluorine compounds. In our opinion, the versatile building blocks used in this method should satisfy the following conditions: 1) readily prepared from commercially available reagents; 2) easy to handle; 3) storage under ordinary conditions without noticeable decomposition; 4) wide applicability. Based on the aforementioned requirements, we focused on the use of vinyl sulfonium salts. This brief review describes the synthesis of five types of fluorinated vinyl sulfonium salts and their reactions. Especially, we featured typical fluorinated groups containing trifluoromethyl (CF₃), difluoromethyl (CF₂H), monofluoromethyl (CFH₂), monofluoro (F) or β-bromotetrafluoroethyl (BrCF₂CF₂) moieties in combination with vinyl sulfonium salts.     

pH-Triggered Molecular Switch Toward Texture-Regulated Zn Anode

Zn electrodes in aqueous media exhibit an unstable Zn/electrolyte interface due to severe parasitic reactions and dendrite formation. Here, a dynamic Zn interface modulation based on the molecular switch strategy is reported by hiring γ-butyrolactone (GBL) in ZnCl₂/H₂O electrolyte. During Zn plating, the increased interfacial alkalinity triggers molecular switch from GBL to γ-hydroxybutyrate (GHB). GHB strongly anchors on Zn surface via triple Zn−O bonding, leading to suppressive hydrogen evolution and texture-regulated Zn morphology. Upon Zn stripping, the fluctuant pH turns the molecular switch reaction off through the cyclization of GHB to GBL. This dynamic molecular switch strategy enables high Zn reversibility with Coulombic efficiency of 99.8 % and Zn||iodine batteries with high-cyclability under high Zn depth of discharge (50 %). This study demonstrates the importance of dynamic modulation for Zn electrode and realizes the reversible molecular switch strategy to enhance its reversibility.     

A highly efficient Pd-C catalytic hydrogenation of pyridine nucleus under mild conditions

A synergistic Pd-C catalytic hydrogenation of 4-pyridinecarboxamides straightforward to 4-piperidinecarboxamide hydrochlorides was developed in the presence of ClCH₂CHCl₂. It provided a novel strategy for highly efficient hydrogenation of pyridine nuclear by using low-cost Pd-C catalyst under mild conditions.     

Dehydrogenation of the NH−NH Bond Triggered by Potassium tert-Butoxide in Liquid Ammonia

A novel strategy for the dehydrogenation of the NH−NH bond is disclosed using potassium tert-butoxide (tBuOK) in liquid ammonia (NH₃) under air at room temperature. Its synthetic value is well demonstrated by the highly efficient synthesis of aromatic azo compounds (up to 100 % yield, 3 min), heterocyclic azo compounds, and dehydrazination of phenylhydrazine. The broad application of this strategy and its benefit to chemical biology is proved by a novel, convenient, one-pot synthesis of aliphatic diazirines, which are important photoreactive agents for photoaffinity labeling.     

A co-activation strategy for enhancing the performance of hematite in photoelectrochemical water oxidation

Hematite(α-Fe_2O_3) is a promising photoanode for photoelectrochemical(PEC) water splitting.However,the severe charge recombination and sluggish water oxidation kinetics extremely limit its use in photohydrogen conversion.Herein,a co-activation strategy is proposed,namely through phosphorus(P)doping and the loading of CoAl-layered double hydroxides(CoAl-LDHs) cocatalysts.Unexpectedly,the integrated system,CoAl-LDHs/P-Fe_2O_3 photoanode,exhibits an outstanding photocurrent density of 1.56 mA/cm~2 at 1.23 V(vs.reversible hydrogen electrode,RHE),under AM 1.5 G,which is 2.6 times of pureα-Fe_2O_3.Systematic studies reveal that the remarkable PEC performance is attributed to accelerated surface OER kinetics and enhanced carrier separation efficiency.This work provides a feasible strategy to enhance the PEC performance of hematite photoanodes.