ngjun Li

Choline Hydroxide: An Efficient and Biocompatible Basic Catalyst for the Synthesis of Biscoumarins Under Mild Conditions

AbstractIn this work, choline hydroxide is found to be an efficient and green catalyst for the synthesis of biscoumarins through the Domino Knoevenagel–Michael reaction of a series of aldehydes with 4-hydroxylcoumarin under mild conditions. A series of aldehydes with different substituted functional groups, especially those which are sensitive to acid, have been converted to biscoumarins with good to excellent isolated yields, and the reactions can be easily scaled up to multigrams. The target products can be simply separated by filtration, and the aqueous solution of choline hydroxide (as filtrate) can then be reused for the next run reaction.Graphical AbstractCholine hydroxide was found to be a green and efficient catalyst for the synthesis of biscoumarins through the Domino Knoevenagel–Michael reactions under mild conditions.

Tetramethylguanidium-based ionic liquids as efficient and reusable catalysts for the synthesis of biscoumarin at room temperature

In this work, a basic ionic liquid, tetramethylguanidium acetate ([TMG][Ac]), was found to be an efficient catalyst for the one-pot preparation of biscoumarins through a domino Knoevenagel–Michael reaction at room temperature. This novel catalytic system avoids the utilization of volatile organic solvents and has excellent tolerance to various functional groups on substrates. The convenient preparation, excellent catalytic efficiency, good reusability and the perspective in scale-up reactions make this catalyst intriguing in industrial applications.

A New Synthetic Protocol for One-Pot Preparations of 5-Halo-1,4-disubstituted-1,2,3-triazoles

In this paper, a new synthetic protocol for one-pot preparations of 5-halo-1,4-disubstituted-1,2,3-triazoles is provided by rational combination of a CuI catalyzed azide–alkyne cycloaddition (CuAAC) reaction and an oxidative halogenation reaction. CuI- N-chlorosuccinimide (NCS) and CuBr-NCS reaction systems are developed, respectively, for effective preparations of 5-iodo-1,4-disubstituted-1,2,3-triazoles and 5-bromo-1,4-disubstituted-1,2,3-trizoles under mild conditions with a high tolerance of various sensitive groups.

Fe2(SO4)3·xH2O on silica: an efficient and low-cost catalyst for the direct nucleophilic substitution of alcohols in solvent-free conditions

Fe2(SO4)3·xH2O on silica has been found to be a novel efficient catalyst for the direct nucleophilic substitution of alcohols in solvent-free conditions. In this reaction system, the alcohols can react with various nucleophilic reagents for the convenient construction of C–C bonds and C–N bonds with the benefits of high conversion, no requirement to use excessive amounts of the nucleophile, only a catalytic amount of iron catalyst required, solvent-free and benign reaction conditions, and the feasible reusability of the catalyst.

Multicomponent Aqueous Synthesis of Iodo-1,2,3-triazoles: Single-Step Models for Dual Modification of Free Peptide and Radioactive Iodo Labeling

Iodo-1,2,3-triazoles are of considerable interest for chemical and biomedical applications. However, current synthetic methods for preparing iodo-1,2,3-triazoles cannot easily be applied to the direct modification of bioactive molecules in water. Through the combination of water-compatible oxidative iodination and the copper-catalyzed alkyne-azide cycloaddition reaction, a novel copper-catalyzed aqueous multicomponent synthetic method for the preparation of 5-iodo-1,2,3-triazoles has been developed. The method is highly effective and selective for substrates including biologically relevant compounds with nucleoside, sugar, and amino acid moieties. Based on this aqueous tandem reaction, a direct single-step multicomponent dual modification of peptide is developed from readily available starting materials. Furthermore, the method could also be applied to concise and fast multicomponent radioactive 125 I labeling from an aqueous solution of commercially available sodium 125 iodide as a starting material.

Hydroxyl Functionalized Lewis Acidic Ionic Liquid on Silica: An Efficient Catalyst for the C-3 Friedel-Crafts Benzylation of Indoles with Benzyl Alcohols

AbstractIn this work, a hydroxyl functionalized Lewis acidic ionic liquid on silica is found to be an efficient heterogeneous catalyst for the C-3 Friedel-Crafts benzylation of indoles with different benzyl alcohols as benzylation agents under mild conditions. This catalytic system benefits from simple operation, work-up and reutilization procedures, wide substrate tolerance, low cost, high catalytic activity and excellent chemo-selectivity. The hybrid combination of hydroxyl functionalized ionic liquid and silica through the formation of hydrogen bond endows this catalyst with high stability in the Friedel-Crafts reaction system, and the catalyst could be easily recycled and reutilized.Graphical AbstractA hydroxyl functionalized Lewis acid ionic liquid supported on silica was found to be an efficient catalyst for the C-3 Friedel-Crafts benzylation reaction of iodole with alcohols. This catalyst benefits from low cost, feasible preparation and reutilization, high catalytic activity and selectivity, and the operation and work-up procedures are very simple.

Betainium-based ionic liquids catalyzed multicomponent Hantzsch reactions for the efficient synthesis of acridinediones

In this study, a series of betainium-based ionic liquids with various anions have been synthesized and their catalytic performances for the Hantzsch reactions have been investigated. It is shown that these ionic liquids have high selectivity for the one-pot production of acridinediones through Hantzsch reactions under mild conditions, and betainium lactate has the highest catalytic activity. This ionic liquid catalyst is very cheap and easy to prepare; the catalytic procedure is very simple and the catalyst can be recycled and reutilized. In addition, the biocompatibility of the raw material of these ionic liquids suggests that this catalytic system may have great industrial potential applications.

A mild and efficient method for formation of C-N bond from benzyl alcohols and sulfonamide, carboxamide, 4-nitroanline and azide catalysed by SnCl4

A mild and efficient method for the formation of C–N bonds is reported with SnCl4 as an inexpensive catalyst. With 10 mol% of SnCl4, the direct substitution reaction of secondary benzyl alcohols with a sulfonamide, a carboxamide, 4-nitroaniline and an azide proceeds well in good to excellent yields at room temperature.

ADP-ribosyl-N3: A Versatile Precursor for Divergent Syntheses of ADP-ribosylated Compounds

Adenosine diphosphate-ribose (ADP-ribose) and its derivatives play important roles in a series of complex physiological procedures. The design and synthesis of artificial ADP-ribosylated compounds is an efficient way to develop valuable chemical biology tools and discover new drug candidates. However, the synthesis of ADP-ribosylated compounds is currently difficult due to structural complexity, easily broken pyrophosphate bond and high hydrophilicity. In this paper, ADP-ribosyl-N3 was designed and synthesized for the first time. With ADP-ribosyl-N3 as the key precursor, a divergent post-modification strategy was developed to prepare structurally diverse ADP-ribosylated compounds including novel nucleotides and peptides bearing ADP-ribosyl moieties.

Sustainable Catalysis Systems Based on Ionic Liquids

Abstract In this chapter, an attempt is made to review the physicochemical properties of ionic liquids and their utilization in several catalysis procedures including transition metal catalysis, enzymatic reactions, dissolution and conversion of biomass, and CO2 transformation. The relationship between structures, physicochemical properties of ionic liquids and their contribution to the sustainability of the related processes is discussed. Also, some representative reactions promoted by acidic and basic functionalized ionic liquids have been reviewed. It is suggested that the combination of cations and anions can provide versatile reaction media and catalysts for the sustainable processes although the rational design of ionic liquids for a particular process is still in its infancy.