Palladium(0) nanoparticles: an efficient catalyst for the one-pot synthesis of polyhydroquinolines

A mild, concise, and efficient protocol for the synthesis of polyhydroquinoline via four component reaction of aromatic aldehydes, dimedone, ethyl acetoacetate or ethyl cyanoacetate, and ammonium acetate using Pd-nanoparticles is described. The same phenomenon was observed in the case of arylmethylene bis(3-hydroxy-2-cyclohexene-1-ones), ethyl acetoacetate, ammonium acetate, and Pd-nanoparticles in one-pot. The present method also allows us to synthesize highly functionalized title compounds from simple and readily available inputs.     

Multi-component synthesis of methylene bis isoxazolo[4,5-b]-pyridine-N-oxides

<正>A three component one-pot protocol was investigated for the synthesis of methylene bis isoxazolo[4,5-b]-pyridine-N-oxides from commercially available materials.     

An efficient green synthesis of proline-based cyclic dipeptides under water-mediated catalyst-free conditions

l-Proline-based cyclic dipeptides were synthesized from N-Boc-protected dipeptide methyl esters under catalyst-free condition using water as a solvent. One-pot deprotection and cyclization have been used as the key steps, providing an efficient and environmentally friendly approach. Clean reaction conditions, easy isolation, and good yields of cyclic dipeptides are the salient features of the proposed methodology.     

Total synthesis of mycophenolic acid

A convergent total synthesis of the natural compound mycophenolic acid 1 is described. The synthetic strategy for the construction of the hexasubstituted aromatic nucleus was based on a ring annulation sequence, involving a Michael addition reaction and intramolecular Dieckmann condensation reaction in situ as the key step. Subsequent transformations of the substituents afforded the target mycophenolic acid 1.     

Bakers' yeast: an environment benign catalyst for the one-pot synthesis of indolyl chromenes and bisindolyl alkanes

A green protocol for one-pot synthesis of pharmacologically important indolyl chromenes and bis(indolyl)alkanes was achieved using Saccharomyces cerevisiae (commonly known as bakers' yeast) as catalyst under room temperature stirring condition. This method is relatively simple, efficient, inexpensive, and environment-friendly.     

Hydroxyl ammonium ionic liquid-catalyzed simple and efficient synthesis of 5-arylidene-2,4-thiazolidinediones under solvent-free conditions

A simple and efficient synthesis of 5-arylidene-2,4-thiazolidinediones by the Knoevenagel condensation of aldehydes with 2,4-thiazolidinedione in the presence of 2-hydroxy ethylammonium propionate under solvent-free conditions is described. The attractive features of this procedure are operational simplicity, high yields, short reaction times, easy to prepare the catalyst, mild and environmentally benign reaction conditions, and recycle of the catalyst.     

Highly efficient and catalyst-free synthesis of unsymmetrical thioureas under solvent-free conditions

A highly efficient and simple synthesis of unsymmetrical thioureas is reported based on the reaction of readily synthesized dithiocarbamates with amines, without using any catalyst under solvent-free conditions. The short reaction time, high yields, and solvent-free conditions are advantages of this method. We did not observe the formation of any symmetric disubstituted thiourea, under these reaction conditions.     

Ultrasound-irradiated Michael addition of amines to ferrocenylenones under solvent-free and catalyst-free conditions at room temperature

A facile Michael addition of ferrocenylenones with aliphatic amines under ultrasound irradiation in the absence of solvent and catalyst at room temperature can afford 1-ferrocenyl-3-amino carbonyl compounds rapidly in high yields, which is also efficient in the aza-Michael reaction of other α,β-unsaturated carbonyl compounds such as chalcone, carboxylic ester, etc. However, aromatic amines do not undergo the conjugate addition at all, and the reactions under existing methods do not proceed or take place in low yield after a long reaction time. Apart from experimental simplicity, generality and selectivity, the advantages of this methodology are the rapid, environmentally benign and less expensive processes, which will contribute to the progress of green chemistry.     

Advancement in synthetic strategies of bisdimedones: Two decades study

Bisdimedones have emerged as an important and versatile moiety in the field of synthetic and medicinal chemistry. It is screened as a precursor for the synthesis of several heterocycles such as acridinediones, xanthenediones, thioxanthenes, and benzopyrans that exhibited immense pharmacological as well as industrial applications. Its extensive characteristics have attracted the scientists to develop various protocols for the synthesis of bisdimedones and their derivatives from the reaction of dimedone with several aldehydes under different environmental conditions using various types of catalysts. This review encapsulates the recent progress in the synthesis of bisdimedone derivatives under several reaction protocols such as the use of nanoparticles, ionic liquids, metal salts, simple organic compounds, and catalyst-free conditions, and so forth in the last 20 years.     

Straightforward and highly efficient catalyst-free one-pot synthesis of dithiocarbamates under solvent-free conditions

[Structure: see text] A highly efficient and simple synthesis of dithiocarbamates is possible based on the one-pot reaction of amines, CS2, and alkyl halides without using a catalyst under solvent-free conditions. The mild reaction conditions, high yields, and broad scope of the reaction illustrate the good synthetic utility of this method. The reaction is a highly atom-economic process for production of S-alkyl thiocarbamates and successfully can be used in high quantities in the pharmaceutical or agrochemical industries.     

Efficient,straightforward, catalyst-free synthesis of medicinally important S-alkyl/benzyl dithiocarbamates under green conditions

Research on Chemical Intermediates - Green synthesis of some novel dithiocarbamate derivatives substituted by aliphatic and aromatic groups as potentially interesting, medicinally important organic...     

A simple,efficient and green procedure for Michael addition catalyzed by [C_4dabco]OH ionic liquid

A dabco-based basic ionic liquid,1-butyl-4-aza-1-azaniabicyclo[2.2.2]octane hydroxide,has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to a b-unsaturated carboxylic esters and nitriles.The method is very simple,and the yields are very high.The catalyst can be recycled several times without much loss of activity.     

10-(4-Hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-3-methyl-1H,10H-pyrano[4,3-b] chromen-1-ones from a pseudo-multicomponent reaction and evaluation of their antioxidant activity

A series of novel 10-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-3-methyl-1H,10H-pyrano[4,3-b]chromen-1-ones were synthesized by a pseudo-three-component reaction of 4-hydroxy-6-methyl-2-oxo-2H-pyran-2-one (TAL) with 2-hydroxyarylaldehydes using different acids as catalysts and solvents. The approach relies on a regioselective cascade reaction involving two molar equiv of the TAL iteratively acting as active methylene in a Knoevenagel condensation and in a Michael addition. The antioxidant activity of the synthesized compounds were determined using the DPPH scavenging assay, being the results dependent on the nature and number of chromone substituents. The compound bearing an ortho-dihydroxy (catechol) moiety showed excellent activity at lower concentrations, while derivatives bearing alkoxy groups as substituents present pro-oxidant activity.     

Sulfamic acid as a green,reusable catalyst for stepwise,tandem & one-pot solvent-free synthesis of pyrazole derivatives

Sulfamic acid (SA) is a bi-functional, cost-effective and reusable green catalyst for the synthesis of 4- (pyrazol-4-yl)methylenepyrazol-5(4H)-one derivatives by one-pot, three-component condensation of pyrazol-4-carbaxaldehydes, β-ketoesters and phenyl hydrazine (Route-I). In addition to this method, another simple condensation of pyrazol-4-carbaxaldehydes with pyrazolone in the presence of SA under the solvent-free condition in good yield is reported. The merits of these protocols are mild conditions, non-aqueous workup, high yields, easy availability of the catalyst, no chromatographic separation and inexpensive solid acid catalyst. Furthermore, SA could be recycled and reused for five times without losing its catalytic activity.     

丙二腈在多组分反应中的应用

丙二腈分子中的氰基作为强吸电子基团活化亚甲基,也是良好的离去基团,以及氰基的碳氮三键可进行加成反应,使得丙二腈是一种非常特别的化合物。它具有非常丰富的反应性质,可以发生Knoevenagel缩合、Michael加成、环化和消去等反应,是进行多组分合成反应的优良试剂。由其参加的多组分合成反应已经成为合成众多碳环和杂环化合物的重要方法。本文综述了丙二腈在多组分反应中的研究进展,介绍了近年来丙二腈参加的多组分反应合成环状化合物的成功事例,展望了丙二腈反应的发展方向。     

Mn-MOF@Pi composite: synthesis,characterisation and an efficient catalyst for the Knoevenagel condensation reaction

We have synthesised new Mn-MOF@Pi composite by encapsulation of piperidine in desolvated Mn-MOF and investigated its catalytic performance in Knoevenagel condensation reaction. The newly developed composite is compatible with various aromatic aldehydes and converting them to the desired Knoevenagel condensation products in good yields and selectivity. Furthermore, composite Mn-MOF@Pi is reusable and shows good catalytic activity than native MOF.     

One-pot synthesis of substituted indolo[1,2-a]quinolines under transition-metal-free conditions

A simple and efficient one-pot synthesis of substituted indolo[1,2-a]quinolines under transition-metal-free conditions has been developed. When 2-fluorobenzaldehyde was treated with substituted 2-methylindoles in the presence of Cs₂CO₃, the desired products were typically obtained in good to excellent yields. This reaction sequence involves a nucleophilic aromatic substitution and a Knoevenagel condensation reaction. Our mechanistic investigation revealed that both reactions could proceed as an intermolecular reaction in the first step.     

Thiamine hydrochloride as a promoter for the efficient and green synthesis of 12-aryl-8,9,10,12 tetrahydrobenzoxanthene-11-one derivatives in aqueous micellar medium

An environmentally benign, three-component, one-pot integrated chemical process has been developed for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzoxanthene-11-one by nucleophilic addition reaction between aldehyde and β-naphthol followed by Michael addition of dimedone, catalyzed by thiamine hydrochloride in aqueous micellar medium with excellent yield. Simple reaction conditions, no requirement of chromatographic separation, short reaction time, ease of isolation, use of inexpensive, easily recoverable and reusable catalyst makes this protocol very interesting from an economic and environmental perspective.     

Simple and efficient synthesis of thysanone methyl ether

The synthesis of thysanone methyl ether is achieved by employing semivioxanthin methyl ether, which in turn is prepared by the tandem Michael addition of an anion of orsellinate to a substituted dihydropyrone.