An ultrasound-promoted green approach for the N-formylation of amines under solvent- and catalyst-free conditions at room temperature

A new environmentally benign, convenient, and facile methodology for the N-formylation of amines is reported using ultrasound irradiation under solvent- and catalyst-free conditions at room temperature. Compared with conventional methods, the main advantages of the present procedure are milder, cleaner and greener conditions, shorter reaction time, higher purity and yields, simpler work-up, and lower generation of waste or pollutions.     

Water-mediated,green, and efficient synthesis of bisquinolones under catalyst-free conditions

Water-mediated, green, and efficient synthesis involving condensation of 4-hydroxy-1-methylquinoline-2(1H)-one (3) with different aromatic and heterocyclic aldehydes (4a–n) leading to 3,3′-(arylmethylene)-bis-(4-hydroxy-1-methylquinolin-2(1H)-one) 5(a–n) under catalyst-free conditions is described. This reaction has an easy workup without using column chromatography and provides excellent yields of the products in shorter reaction times. It does not require any catalyst and uses water as the medium which is the greenest solvent. 3 required in this work was itself obtained by condensation of N-methylaniline (1) with malonic acid (2) in the presence of POCl₃ using a previously reported procedure.     

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.     

Yttrium-catalyzed heterocyclic formation via aerobic oxygenation: A green approach to benzothiazoles

The YCl₃-catalyzed aerobic oxidative cyclization reaction for the synthesis of benzothiazoles has been developed.This method provides a practical,effective and green synthetic approach to benzothiazoles which are important units in many biologically active compounds.     

Water-controlled nitro-oximation of alkenes under catalyst-free conditions

A convenient and precise nitration and oximation of alkenes with tert-butyl nitrite has been reported, yielding α-nitro ketoximes in satisfactory yields with broad substrate generality and excellent stereoselectivity under mild conditions. Experiments indicate that tert-butyl nitrite serves as both NO and NO₂ sources and water plays a key role in this difunctionalization reaction.     

Synthesis of sulfides under solvent- and catalyst-free conditions

Abstract  A simple, highly efficient, and green protocol has been developed for preparation of sulfides from alkyl or aryl thiols and benzyl-, allyl-, t-butyl, and adamantyl halides under solvent- and catalyst-free conditions. Graphical abstract        

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...     

One-step furan ring formation: Synthesis of furo[3,2-h]quinolones

The one-pot reaction of ethyl 1-cyclopropyl-6,7,8-trifluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate ( 6 ) with tert-butyl acetoacetate gave 3-tert-butyl 7-ethyl 9-cyclopropyl-4-fluoro-6,9-dihydro-2-methyl-6-oxofuro[3,2-h]quinoline-3,7-dicarboxylate ( 5 ). This regioselective cyclization was rationalized by the Hard and Soft Acids and Bases principle. By use of a similar furan-forming reaction, we prepared 2-(amino-methyl)furo[3,2-h]quinoline-7-carboxylic acid 4 . Compound 4 showed weak antibacterial activity.     

Catalytic dehydrocyclization of diethylamine with the formation of a five-membered heterocyclic ring

Summary It was found that when diethylamine is passed over platinized carbon, pyrrole and n-butylamine are formed, i.e., dehydrocyclization takes place which is analogous to the C₅-dehydrocyclization of paraffins.     

Synthesis of adenosine-based fluorosides containing a novel heterocyclic ring system

A novel class of fluorescent adenosine derivatives (fluorosides) containing the previously unreported 8-(3H-[1,2,3]triazol-4-yl)-9H-purine heterocyclic ring system is reported, with Sonogashira cross-coupling and [3+2]-cycloaddition reactions being the key steps in the synthesis.     

One-pot formation of nitrogen-containing heterocyclic ring systems using a deprotection-cyclisation-asymmetric reduction sequence

A one-pot sequence of amine deprotection, intramolecular C=N bond formation and subsequent asymmetric reduction may be promoted by a ruthenium catalyst.     

The green synthesis of 2,3-dihydroquinazolin-4(1H)-ones via direct cyclocondensation reaction under catalyst-free conditions

ABSTRACT

A simple and environmentally benign method is described for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones by direct cyclocondensation of 2-aminobenzamide with aromatic aldehydes using water as the reaction medium. The parameters such as temperature, substrate molar ratio and reaction time were examined to establish the optimal synthetic process. The present procedure has advantages of low cost, mild reaction conditions, simple workup process, simply purification, excellent yields and no use of catalyst and hazardous organic solvents.     

Solar radiation-assisted one-pot synthesis of 3-alkylated indoles under catalyst-free conditions

Solar radiation-assisted green approach was developed for the chemoselective synthesis of 3-alkylated indoles via Yonemitsu-type condensation under catalyst-free conditions. The desired products were formed by one-pot three-component reaction of indole, aromatic aldehydes, and β-dicarbonyl compounds in polyethylene glycol-400 (PEG-400). The scope and generality of the presented approach were extended by various aromatic aldehydes and CH activated compounds. Using non-volatile solvent and renewable energy resources, absence of any catalyst, energy conservation, and the selective production of heterodimer product instead of homodimer adducts such as bisindole or xanthine, increase the economic and environmental effectiveness of the present protocol.     

Unexpected simultaneous synthesis of trisubstituted quinolines and acylhydrazones under catalyst-free conditions

Trisubstituted quinolines and acylhydrazones were unexpectedly prepared from a reaction of N′-((2-aminophenyl)(phenyl)methylene)benzohydrazides with acetylenic esters. Using of N′-((2-aminophenyl)(phenyl)methylene)benzohydrazides led to obtain not only quinoline, but also a second pharmaceutical important product acylhydrazone. Notably, excellent yields, operational simplicity, short reaction times, and the avoidance of the use of catalysts make this approach an attractive complementary method to produce quinoline-2,3-dicarboxylates. The crystal structure of 5a was determined using single-crystal X-ray crystallography. The results showed that crystal packing diagram of 5a is of two pairs of molecules that have two independent alternate intermolecular 1D-polymeric H-bonds between two perpendicular molecules.     

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.     

Chemo-, site-selective reduction of nitroarenes under blue-light,catalyst-free conditions

The tandem reaction of photoinduced double hydrogen-atom transfer and deoxygenative transborylation for chemo-and site-selective reduction of nitroarenes into aryl amines under catalyst-free, room temperature conditions was disclosed in excellent yields. In this reaction, isopropanol（ⁱPrOH） was used as hydrogen donor and tetrahydroxydiboron [B₂（OH）₄] as deoxygenative reagent with green, cheap, and commercially available credentials. In particular, a wide range of...