Defect engineering of electrocatalysts for organic synthesis

Electrocatalytic organic synthesis has attracted considerable research attention because it is an efficient and eco-friendly strategy for converting energy sources to value-added chemicals.Defect engineering is a promising strategy for regulating the electronic structure and charge density of electrocatalysts.It endows electrocatalysts with excellent physical and physicochemical properties and optimizes the adsorption energy of the reaction intermediates to reduce the kinetic barriers of the electrosynthesis reaction.Herein,the recent advances related to the use of electrocatalysts for organic synthesis with respect to defects are systematically reviewed.The roles of defects in anodic and cathodic reactions,such as the syntheses of alkanes,alkenes,alcohols,aldehydes,amides,and carboxylic acids,are reviewed.Furthermore,the relationship between the defective structure and electrocatalytic activity is discussed by combining experimental results and theoretical calculations.Finally,the challenges,opportunities,and development prospects of defective electrocatalysts are examined to promote the development of the field of electrocatalytic organic synthesis.This review is expected to help understand the vital role of defects in catalytic processes and the controllable synthesis of efficient electrocatalysts for the production of high-value chemicals.

Carbohydrate-derived porous carbon materials:An ideal platform for green organic synthesis

Porous carbon materials have attracted much attention in the field of organic synthesis in recent years,due to their tunable properties,excellent catalytic activity and stability.Biomass-based carbohydrates emerge as an ideal precursor for the generation of these materials owing to their renewability,low cost,non-toxicity and high content of functional groups.Thus,carbon materials prepared from carbohydrates is of considerable importance for the sustainable development of organic chemistry.The present review not only summarizes recent examples of carbohydrate-derived porous carbon material-catalyzed organic reactions including the oxidation,hydrogenation,cross-coupling,esterification and condensation reactions,but also introduces the preparation and functionalization strategies of these materials.Furthermore,the challenges and opportunities of organic synthesis over these sustainable materials have also been addressed.This review will stimulate further research on exploring novel carbohydrate-derived porous carbon materials and new sustainable organic synthetic processes over these materials.

Merging cobalt catalysis and electrochemistry in organic synthesis

There is an increasing demand of using the low-cost and sustainable cobalt to replace its noble congeners(rhodium and iridium)as reflected by the recent upsurge of cobalt catalysis in the diverse organic transformations.Since all the redox reactivity of cobalt catalysis highly relies on the capability of the interconversion between their oxidation states(most frequently+1,+2 and+3),electrochemistry perfectly meets such a require ment owing to its outstanding perfo rmance in the redox manipulation.In this review,we highlight the recent advances in the merger of cobalt catalysis and electrochemistry in organic synthesis.

Control of selectivity in organic synthesis via heterogeneous photocatalysis under visible light

Organic synthesis driven by heterogeneous catalysis is a central research theme to both fundamental research and industrial production of fine chemicals.However,the employment of stoichiometric strong oxidizing or reducing reagents(e.g.,K_(2)Cr_(2)O_(7) and LiAlH_(4))and harsh reaction conditions(e.g.,high temperature and pressure)always leads to the products of overreaction and other by-product residues(e.g.,salt and acid waste).Thus the poor control of product selectivity and tremendous energy consumption result in the urgent demand to develop novel technologies for heterogeneous catalysis.Given the current global theme of development in CO_(2) reduction and sustainable energy utilization,one promising protocol is heterogeneous photocatalysis.It enables sustainable solar-to-chemical energy conversion under mild conditions(e.g.,room temperature,ambient pressure,and air as the oxidant)and offers unique reaction pathways for improved selectivity control.To accurately tailor the selectivity of desired products,the electronic structure(e.g.,positions of valence-band maximum and conduction-band minimum),geometric structure(e.g.,nanorod,nanosheet,and porous morphology),and surface chemical micro-environment(e.g.,vacancy sites and co-catalysts)of heterogeneous photocatalysts require rational design and construction.In this review,we will briefly analyze some effective photocatalytic systems with the excellent regulation ability of product selectivity in organic transformations(mainly oxidation and reduction types)under visible light irradiation,and put forward opinions on the optimal fabrication of nanostructured photocatalysts to realize selective organic synthesis.

Analysis of the Environment-friendly Synthesis Approach and Technology Based on CO_2 Instead of the Organic Carbon Sources in Coal and Oil

The ways and technology of synthesis of alcohol, ether, ester, amine ester, lactone, polyester, carbamide and diamond based on CO2 were explored. Using CO2 as potential organic carbon resources not only solves environmental problem, but also eases shortage of resources.

Application of carbene reactive intermediates in organic synthesis——Ⅲ.Reaction of difluorocarbene with trimethylsilyl enol ethers

The addition of difluorocarbene generated from phenyl(trifluoromethyl)mercury and anhydrous sodium iodide,with trimethylsilyl enol ethers derived from cyclohexanone,cycloheptanone, 3-pentanone and acetophenone was described.The corresponding 2,2-difluoro-1-trimethylsilyloxy- cyclopropanes were obtained in good yields.The thermal stability of these cyclopropyl derivatives was affected by the molecular strain and the nature of their substituents.Thus,1-trimethylsilyloxy- cyclopentene reacted with difluorocarbene to give only 2-fluoro-2-cyclohexen-1-one instead of the expected 1-trimethylsilyloxy-6,6-difluorobicyclo[3.1.0]hexane,and a mechanism for its formation was proposed.

Organic Melt Crystallization as a Method for Synthesis of Supramolecular Complexes

The most simple method for solventless synthesis of supramolecular complex of CMCR·2BPY·BZP, [CMCR = C-methylcalix[4]resorcinarene, BPY = 4,4'-bipyridine, BZP = benzophenone], is proposed. Although CMCR by itself is high melting point compound (above 300°C), CMCR was found to be dissolved in melt mixture of BPY and BZPeven below 120°C. In the mixture of the three components, the reaction occurs to form CMCR·2BPY·BZP supramolecular complex.

Design, Synthesis and Biological Activity of Substituted-N-[4-(substituted-phenylsulfamoyl)phenyl]benzamide as Potential AHAS Inhibitors

Based on the crystal structure of AHAS/sulfonylurea complex, we obtained 296 compounds with low binding energy towards AHAS via virtual screening. One series of them have been synthesized. Preliminary bioassay indicated that some compounds displayed good herbicidal activity on rape and bamygrass and inhibited AHAS to some extent. This study indicated the rationality of our molecular design based on the crystal structure of target enzyme.

Synthesis and Nonlinear Optical Property of a Series of New Chromophores Containing Furan Ring as the Only Conjugation Bridge

This paper reports the synthesis and the nonlinear optical property of a series of new chromophores which contain furan ring as the only conjugation bridge for the first time. They are characterized by UV-VIS, FT-IR, 1H NMR, MS and elemental analysis. Their dipole moment and the first-order molecular hyperpolarizability (b) are calculated and compared with those of the analogues containing either benzene or thiophene as the conjugation bridge.

Solid-phase Synthesis of-Haloaldehydes from Polymer-supported 4-(Phenylseleno)morpholine

Polystyrene-supported 4-(phenylseleno)morpholine was synthesized and could be used as an efficient ?selenenylating agent for saturated aldehydes. ?Haloaldehydes were prepared by reaction of polystyrene-supported ?selenoaldehydes with bromine or sulfuryl chloride in good yield and high purity.

Solid-Phase Stereoselective Synthesis of(E)-1,2-Disubstituted Ethenes from Polymer-Sopportedα-Selenoaldehydes

Reaction of polymer-supported a-selenoaldehydes with Grignard reagents afforded polymer-bound B-hydroxyalkyl selenides, which treated with thionyl chloride and triethylamine leading to (E)-1, 2-disubstituted ethenes in good yield.

Traceless solid-phase synthesis of 3-substituted isoxazoles from polystyrene-supported vinyl selenide

A novel facile procedure for traceless solid-phase synthesis of 3-substituted isoxazoles in good yields and with excellent purities using polymer-supported vinyl selenide has been developed.

Solid-phase synthesis of (Z)-allyl iodides from 3-acetoxy-2-methylene-alkanoates with recyclable polymer-supported selenium bromide

Reaction of polystyrene-supported lithium selenide with 3-acetoxy-2-methylene-alkanoates afforded the corresponding allyl selenide resins and subsequent cleavage from the polymer by treating with methyl iodide to furnish （Z）-allyl iodides in good yields and high purities. The polymeric selenium reagent can be regenerated and reused. So it is a environmentally benign reagent.

THE ASYMMETRIC SYNTHESIS OF AMINO ACIDS UNDER POLYMER-SUPPORTED PHASE TRANSFER CATALYTIC CONDITION

The optical alpha-amino acids were synthesized under room temperature by alkylation of N-(diphenyl methylene) glycine t-butyl ester under polymer-supported phase transfer conditions using polymer-supported cinchonine (or quinine) alkaloids as chiral phase transfer catalysts and dichloromethane as solvent, followed by hydrolysis of the above intermediates introduced to the final products-optical alpha-amino acids. This is a new method for the asymmetric synthesis of alpha-amino acids. The influences of catalyst, temperature, substrates, and organic solvents on the chemical yield and optical purities of products were studied.