An efficient one-pot,multi-component diastereoselective synthesis of functionalized cyclopenta[c]chromenes

A novel one-pot, multi-component diastereoselective synthesis of functionalized cyclopenta[c]chromenes is described. This transformation proceeds via a Michael addition-cyclization reaction sequence between trialkyl phosphites, dialkyl acetylenedicarboxylates and in situ generated 2-(1-(2-oxo-2H-chromen-3-yl)alkylidene)malononitriles from the condensation of 3-acyl-2H-chromen-2-ones and malononitrile.     

An efficient, microwave-assisted, one-pot synthesis of indoles under Sonogashira conditions

A microwave-assisted, one-pot, three-component coupling reaction for the synthesis of indoles has been developed. The reaction is carried out in two steps under standard Sonogashira coupling conditions from an N-substituted/N,N-disubstituted 2-iodoaniline and a terminal alkyne, followed by the addition of acetonitrile and an aryl iodide. A variety of polysubstituted indoles have been prepared in moderate to excellent yields using the present method.     

Efficient synthesis of diarylidene octahydroacridines by one-pot multi-component tandem reactions

A one-pot multi-component reaction is developed for the efficient synthesis of 4,5-dibenzylidene octahydroacridines in high yields. The reaction is performed by the tandem reaction of three molar equivalent aromatic aldehydes with two molar equivalent 4-alkylcyclohexanone in the system of NH₄OAc/HOAc under microwave irradiation.      

Efficient and rapid synthesis of regioselective functionalized potassium 1,2,3-triazoletrifluoroborates via 1,3-dipolar cycloaddition

In this study, we present a previously unreported method of preparing regiospecific organo-[1,2,3]-triazol-1-aryl-trifluoroborates from haloaryltrifluoroborates via a one-pot 1,3-dipolar cycloaddition reaction. We found that the use of either electron-rich or electron-deficient haloaryltrifluoroborates led to the desired cycloaddition products with good to excellent yields. Furthermore, we successfully carried out the cross-coupling reactions of the obtained triazoles with various aryl halides by means of the Suzuki-Miyaura reaction in the presence of 3 mol % of Pd(PPh₃)₄ catalyst in a 20% aqueous 1,4-dioxane solution at 100 °C; all these reactions yielded complete conversion to the corresponding products. Besides providing a high level of personnel safety, our highly versatile approach allows the preparation of functionalized organotrifluoborates containing 1,2,3-triazoles with retained functionality.     

A green and convenient approach for the synthesis of methyl 6-amino-5-cyano-4-aryl-2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylates via a one-pot, multi-component reaction in water

A green and efficient one-pot, four-component synthesis of methyl 6-amino-5-cyano-4-aryl-2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylates in water is described. The method is catalyst-free, atom-economical, and does not involve tedious work-up or purification affording the target compounds in good yields.     

A base-free, one-pot diazotization/cross-coupling of anilines with arylboronic acids

Pd-catalyzed one-pot diazotization/cross-coupling is realized for the synthesis of biaryls directly from anilines and arylboronic acids.     

Coupling of thioamides with 4-bromocrotonate esters and subsequent conjugate addition for the rapid one-pot synthesis of functionalized thiazolines

An efficient one-pot synthesis of functionalized thiazolines via the coupling of thioamides with 4-bromocrotonate esters is described. A range of aryl- and alkyl-thioamides with various substitutions are well-tolerated. Additionally, the presence of the exocyclic ester functionality provides a convenient handle for the synthesis of more complex thiazoline-containing natural products and biologically-relevant compounds.     

Convenient synthesis of photochromic symmetrical or unsymmetrical bis(heteroaryl)maleimides via the Suzuki-Miyaura cross-coupling reaction

A general method for the synthesis of symmetrical or unsymmetrical bis(heteroaryl)maleimides by a one-pot procedure involving Suzuki-Miyaura cross-coupling sequence was developed on the basis of the reaction of 3,4-diiodo-1-benzyl-1H-pyrrole-2,5-dione with cyclic boronate esters using PdCl₂(dppf) as the catalyst. Photochromic properties of the products were examined.     

A one-pot synthesis of nitrogen-containing heteroaryl α-keto amides from heteroaryl halides

The S_NAr-type reaction of the piperidine amide of cyanoacetic acid with a series of heteroaryl halides followed by in situ oxidation of the resultant anion with peracetic acid provided a convenient, one-pot protocol for preparative access to heteroaryl α-keto amides. In this procedure, the amide of cyanoacetic acid functions as an Umpolung-type synthon of the α-keto amide moiety.     

A rapid, one-pot, microwave-influenced synthesis of spiro-2,5-diketopiperazines via a cascade Ugi/6-exo-trig aza-Michael reaction

A rapid, cascade reaction process has been developed to access biologically validated spiro-2,5-diketopiperazines. The facile and environmentally benign method capitalizes on commercially available starting reagents for a sequential Ugi/6-exo-trig aza-Michael reaction, water as a solvent, and microwave irradiation without any extraneous additives.     

Development of environmental friendly synthetic strategies for Sonogashira cross coupling reaction: An update

Sonogashira cross coupling is a well-known reaction for the formation of carbon–carbon bond. It involves the coupling of aryl halides with terminal alkynes to synthesize versatile functionalized alkyne scaffolds having diverse applications. Many of the natural products and important pharmaceutical drugs can be obtained through this reaction. In this regard, hectic progress has been put by the synthetic chemists to make this cross coupling more effective. This review article discloses mild and environmental friendly reaction conditions of Sonogashira cross coupling developed during 2013–2018.     

A pseudo multi-component electrochemical synthesis of spiro dihydrofuran derivatives

An electrochemical strategy to the assembly of tricyclic spiro dihydrofuran scaffold via the reaction of aryl aldehyde and dimedone has been developed successfully. This protocol has the advantages of high yields, wide application scope and an environmental benign procedure compared with the reported methods.     

Efficient synthesis of functionalized pyrimidones via microwave-accelerated rearrangement reaction

An efficient synthesis of functionalized pyrimidones via microwave-accelerated rearrangement reaction of amidoxime DMAD adducts is described. In most cases, the pyrimidone formation was furnished in reasonable yield after 2 min of microwave irradiation.     

An isocyanide based multi-component reaction under catalyst- and solvent-free conditions for the synthesis of unsymmetrical thioureas

A new and efficient method for the synthesis of thiourea derivatives by a sequential one-pot, three-component reaction between aromatic isocyanides, amines, and 1,2-di-tert-butyldisulfane (DTBS) was developed and 27 different examples were synthesized in good to excellent yields. DTBS was identified as an effective sulfur surrogate without the use of both catalysts and solvents. This protocol does not employ any transition metal catalyst or special experimental setup.     

A facile and expeditious microwave-assisted synthesis of 4-aryl-2-ferrocenyl-quinoline derivatives via multi-component reaction

An efficient and rapid route for the synthesis of 4-aryl-2-ferrocenyl-quinoline derivatives through microwave-assisted multi-component reaction of acetylferrocene with aromatic aldehyde and dimedone in the presence of ammonium acetate using DMF as reaction media at 100 °C is described. This novel procedure lends itself well to combinatorial methods, providing the target heteropolymetallic compounds in excellent yield without further purification.     

Synthesis of indolequinones via a Sonogashira coupling/cyclization cascade reaction

A mild strategy for constructing indolequinone motifs is described on the basis of the Sonogashira reaction and a copper-catalyzed intramolecular cyclization cascade reaction. The first step involves the palladium- and copper-catalyzed reaction between halogenated naphthoquinone and terminal acetylene to generate a coupling product, which then reacts in a copper-catalyzed intramolecular cyclization with the nitrogen functional group adjacent to the carbon-carbon triple bond.     

Tandem synthesis of functionalized hexaalkyl benzoisoquinolinopyrrolonaphthyridine-hexacarboxylate,via isoquinoline based multi-component reaction

An expedient,synthetic method to fused polycyclic derivatives of isoquinoline is described via tandem reaction of isoquinoline,dialkyl acetylenedicarboxylates and dialkyl chloromalonate.     

Three-component domino reaction synthesis of highly functionalized bicyclic pyrrole derivatives

An efficient one-pot synthesis of highly functionalized bicyclic pyrrole derivatives by a three-component domino reaction of heterocyclic ketene aminals (HKAs), arylglyoxal monohydrate, and indoles in ethanol medium catalyzed by acetic acid is described. In this procedure, three sigma bonds were formed simultaneously. The present synthesis features excellent regio-selectivity, easy purification as well as simple starting materials.     

Potassium phthalimide-catalysed one-pot multi-component reaction for efficient synthesis of amino-benzochromenes in aqueous media

2-Amino-4-aryl-4H-benzo[h]chromenes and 3-amino-1-aryl-1H-benzo[f]chromenes were prepared by treating cyano-methylene compounds (malononitrile or ethyl cyanoacetate), substituted aromatic aldehydes, and naphtholic compounds in the presence of potassium phthalimide as a green, mild, efficient, and commercially available organocatalyst in aqueous media. The procedure was readily conducted and affords remarkable advantages such as safety, short reaction times, environmentally benign milder reaction conditions, no organic solvent required, and high yields.     

A rapid approach for the copper,amine, and ligand-free Sonogashira coupling of 4-methyl-7-nonafluorobutylsulfonyloxy coumarins under microwave irradiation

A rapid, efficient, and reliable access for the synthesis of an assortment of 4-methyl-7-alkyl/aryl/heteroaryl alkynyl coumarins has been developed by the copper, amine, and ligand-free Sonogashira cross-coupling reaction of 4-methyl-7-nonafluorobutylsulfonyloxy coumarin with various terminal alkynes under microwave irradiation. In the presence of a suitable catalyst, base, and solvent, the coupling reaction proceeded smoothly to give the diaryl alkynes in satisfactory to exceptional yields. Nonaflates coupled more efficiently than the corresponding triflates which yielded the detriflated product as well as the hydrolyzed product as competing side products along with the required product. The utilization of TBAF·3H₂O as a mild base as well as a solvating agent was the key for success of the reaction.