Green and mild laccase-catalyzed aerobic oxidative coupling of benzenediol derivatives with various sodium benzenesulfinates

The oxidative coupling reaction between hydroquinone or catechols and various sodium benzenesulfinates was investigated using the laccase from Trametes versicolor, in the presence of O₂ in a phosphate buffer solution at room temperature to afford sulfonyl benzenediols in 75–95% yield.     

Fe-based metal-organic frameworks for the synthesis of N-arylsulfonamides via the reactions of sodium arylsulfinates or arylsulfonyl chlorides with nitroarenes in water

A newly developed chemoselective reaction of sodium arylsulfinates or arylsulfonyl chlorides with nitroarenes has been disclosed. The chemistry, in which non-toxic water and recyclable iron-based metal-organic frameworks are employed as the solvent and catalyst, respectively, provides an efficient approach for the generation of N-arylsulfonamides, which are widely present in biologically active compounds and drugs, rendering this methodology attractive to both synthetic and medicinal chemistry.     

温和条件下钒催化氧化胺、醇和胺直接合成亚胺(英文)

开发了钒催化氧化胺、醇和胺直接合成亚胺催化体系,无须额外的添加剂或促进剂,空气作为环境友好的氧源,温和条件下,能高收率地得到各种对称和非对称亚胺,并且催化剂非常容易制备和使用.该催化体系对含杂原子亚胺的合成也非常有效.     

Practical CuCl/DABCO/4-HO-TEMPO-catalyzed oxidative synthesis of nitriles from alcohols with air as oxidant

A mild and efficient copper-catalyzed aerobic oxidative synthesis of nitriles directly from alcohols and aqueous ammonia with air as the terminal oxidant was disclosed. A variety of nitriles are obtained in good to excellent yields.     

An improved procedure for the synthesis of 4-methylimidazol-2-one

A novel one-pot synthetic method of 4-methylimidazol-2-one is described. The target compound is conveniently synthesized from sodium diformylamide, a modified Gabriel reagent prepared, through condensation, hydrolyzation and cyclization reactions without separating intermediates, its total yield is 75.8%.     

基于四氮配体的铜配合物/TEMPO催化的苄醇与烯丙基醇的氧化反应

发展了非血红素类四氮配体的铜配合物和2,2,6,6-四甲基哌啶-氮-氧自由基(TEMPO)相结合的催化体系,应用于分子氧参与的伯醇氧化反应.该体系具有条件温和、高效、高选择性、无需任何助剂和底物(包括苄醇、烯丙基醇和含杂原子伯醇)使用性强等优点.此外,利用高分辨质谱和紫外-光谱等对反应活性中间体进行了初步探讨.     

Application of laccase/DDQ as a new bioinspired catalyst system for the aerobic oxidation of tetrahydroquinazolines and Hantzsch 1,4-dihydropyridines

Laccase/DDQ as a new bioinspired quinone-based cooperative catalytic system was used for the biomimetic aerobic oxidative synthesis of 2-substituted quinazolines and Hantzsch pyridines from the oxidative cyclocondensation of 2-aminobenzylamine and aldehydes and the oxidative aromatization of 1,4-dihydropyridines, respectively. The products were obtained in good to high yields in a phosphate buffer (0.1 M, 12.5 mL, pH 4.5) and acetonitrile (4 vol%) mixture as a solvent. These methods are more eco-friendly, efficient, simple, and practical than other currently available ones because of mild reaction conditions and because they are free from any halide and toxic and expensive transition metals. Therefore, these methods can be applied in pharmaceutical and other sensitive synthetic procedures.     

Copper-catalyzed aerobic oxidative cyclization protocol for the synthesis of quinazolines via amination of C(sp3)-H bonds of methylazaarenes

A new aerobic copper-catalyzed three-component synthesis of azaaryl-substituted quinazolines has been developed, which featured inexpensive methylazaarenes as C1 sources, easily available copper salts as the catalysts and O₂ as a sole oxidant. The transformation had very good substrate applicability towards methylazaarenes, and various azaaryl-substituted quinazolines were obtained in moderate to good yields.     

Selective synthesis of functionalized pyrazoles from 5-amino-1H-pyrazole-4-carbaldehydes with sodium nitrite: 5-Amino-4-nitrosopyrazoles and pyrazole-4-carbaldehydes

A novel and efficient redox reaction was developed to react 5-amino-1H-pyrazole-4-carbaldehyde with sodium nitrite (NaNO₂) in an acidic solution (HCl/MeOH) to generate 5-amino-4-nitrosopyrazole, pyrazole-4-carbaldehyde, or diazenylpyrazole selectively. The results showed that 5-amino-4-nitrosopyrazoles were formed as the major product in the diluted acidic solution (≤2 N HCl in MeOH solution) through redox, formylation, and nitrosation reactions of NaNO₂. Intriguingly, pyrazole-4-carbaldehyde was the main product under 6 N HCl in MeOH solution.     

A novel method for the synthesis of 5-substituted 1H-tetrazole from oxime and sodium azide

A simple and efficient protocol is developed for the synthesis of 5-substituted 1H-tetrazoles from various oximes and sodium azide (NaN₃) by using copper acetate as a catalyst.     

Green approach for the synthesis of 4-coumarin-4H-pyrans from 4-formylcoumarins and their antibacterial study

A series of 4H-pyranocoumarin derivatives have been successfully synthesized under eco-friendly condition using triethylamine as a catalyst in short reaction time with excellent yield at room temperature. All the synthesized compounds were characterized by spectral analysis and screened for their antibacterial activity against Escherichia coli and Staphylococcus aureus, the results are quite promising.     

CuFe2O4 nanoparticles: a magnetically recoverable and reusable catalyst for the synthesis of 5-substituted 1H-tetrazoles

An efficient and economical protocol for the synthesis of 5-substituted 1H-tetrazoles from various nitriles and sodium azide is described using magnetically recoverable and reusable CuFe₂O₄ nanoparticles. A wide variety of aryl nitriles underwent [2+3] cycloaddition under mild reaction conditions to afford tetrazoles in good to excellent yields. The catalyst was magnetically separated and reused five times without significant loss of catalytic activity.     

New route for the synthesis of benzimidazoles by a one-pot multistep process with mono and bifunctional solid catalysts

One-pot multistep reactions involving a new environmentally friendly catalytic procedure have been developed for the synthesis of benzimidazoles. Benzimidazole derivatives with biological and pharmaceutical interest have been prepared by a one-pot four step process with a solid catalyst containing basic and oxidation sites. The four steps refer to: (a) oxidation of the alcohol; (b) cyclocondensation of the aldehyde formed with ortho-phenylenediamines, (c) oxidation of the carbon-nitrogen bond, (d) N-alkylation reaction. The process is illustrated by the synthesis of 1,2-disubstituted benzimidazole derivative with antiviral activity.     

An eco-friendly procedure for one-pot synthesis of β-phosphonomalonates: micellar solution of sodium stearate catalyzes tandem Knoevenagel-phospha-Michael reaction of aldehydes, malonitrile, and phosphites in aqueous media

A new, one-pot convenient method for the synthesis of a variety of β-phosphonomalonates by a tandem Knoevenagel-phospha-Michael reaction of phosphite esters with aryl/heteroaryl/alkyl aldehydes and malonitrile in an aqueous micellar solution of sodium stearate is described. This method offers several advantages, such as using a cheap and environmentally benign reaction media, low loadings of sodium stearate as catalyst and offers good yields.     

Gram scale,metal-free and selective aerobic oxidation of alcohol and alkyl benzenes using homogeneous recyclable TAIm[MnO4] oxidative ionic liquid under mild conditions: Microwave/ ultrasonic-assisted to carboxylic acid

A homogeneous catalyst-free system has been developed for the selective oxidation of alcohols and alkyl benzenes to the corresponding carbonyl compounds using a recyclable TAIm[MnO₄] oxidative ionic liquid. The reactions were performed in the presence of previously reported TAIm[MnO₄]/ TAIm[OH] ionic liquids and KMnO₄ at ambient temperature under solvent-free conditions. Benzyl alcohols were selectively transferred to benzaldehydes, while under ultrasonic or microwave irradiation, they oxidized to benzoic acid selectively and directly. Scalability of the process also studied at high scale. Also, the ionic liquid could be readily recycled from the aqueous mixture and reused for several consecutive times without any pre-treatment and loss of catalytic activity. In this work, the highly active and toxic KMnO₄ salt has been transformed into a mild recyclable oxidant reagent with high selectivity towards alcohol oxidation.     

Efficient and mild cyclization procedures for the synthesis of novel 2-amino-4H-pyran derivatives with potential antitumor activity

A series of novel 2-amino-4H-pyran derivatives have been synthesized via a three-component reaction of α,β-unsaturated ketone derivatives, malononitrile, aldehydes in excellent yields, using DBU as a catalyst and ethanol as a cheap, safe, and environmentally benign solvent under mild conditions. Their antitumor activity was evaluated in three human tumor cell lines, including human colon cancer （HCT116）, human cervical cancer （Hela）. and non-small cell lung cancer （H1975）.     

4-Phenyl-1,2,4-triazole-3,5-dione as a novel and reusable reagent for the aromatization of 1,4-dihydropyridines under mild conditions

4-Substituted 1,3,4-triazole-3,5-diones were used as effective and recyclable oxidizing agents for the oxidation of 1,4-dihydropyridines to the corresponding pyridine derivatives under mild conditions with good to excellent yields.     

Transition-metal-free oxidative amidation of benzyl alcohols with amines catalyzed by NaI: a new method for the synthesis of benzamides

A simple, inexpensive, and efficient method for the synthesis of benzamides via the reaction of benzyl alcohols and amine hydrochloride salts in the presence of NaI as a green catalyst is described. Various derivatives of benzamide were synthesized in moderate to good yields using this method.