Microwave‐induced Stereoselectivity in Synthesis of trans‐4‐Aryl‐3‐methyl‐6‐oxo‐4,5,6,7‐tetrahydro‐2H‐pyrazolo[3,4‐b]pyridine‐5‐carbonitriles

A facile synthesis of trans isomers of 4‐aryl‐3‐methyl‐6‐oxo‐4,5,6,7‐tetrahydro ‐ 2H ‐ pyrazolo[3,4‐b]pyridine‐5‐carbonitriles via three‐component condensation reaction of an aldehyde, 3‐amino‐5‐methylpyrazole and ethyl cyanoacetate in acetonitrile has been developed under microwave irradiation. This one‐pot reaction proceeds without any catalyst in short times and gives the product in high selectivities and high yields.     

One‐pot synthesis of novel N‐cyclopropyldecahydroacridine‐1,8‐dione derivatives under microwave irradiation

A series of new N‐cyclopropyldecahydroacridine‐1,8‐dione derivatives were synthesized by one‐pot reaction of aromatic aldehyde, dimedone (or 1,3‐cyclohexanedione) and cyclopropanamine in solution of glycol and water under microwave irradiation with excellent yields (78‐94%) and short reaction time (5‐10 min).     

Glycerol: A Promising Benign Solvent for Catalyst‐free One‐pot Multi‐component Synthesis of 1H‐Pyrozolo[1,2‐b]phthalazine‐5,10‐diones and 2H‐Indazolo[2,1‐b]phthalazine‐triones Under Controlled Microwaves Irradiation

A simple green and efficient one‐pot multi‐component synthesis of 1H‐pyrozolo[1,2‐b]phthalazine‐5,10‐diones and 2H‐indazolo[2,1‐b]phthalazine‐triones has been developed utilizing one‐pot multi‐component reaction of aromatic aldehydes, active methylene reagents, phthalic anhydride, and hydrazine hydrate or alternatively phthalhydrazide in glycerol without catalyst under controlled microwave heating. The current synthetic protocol offers several advantages such as excellent yields, high EcoScale and atom economy, simple working up reactants and products, and the absence of hazardous catalysts or solvents.     

Construction of a combinatorial library of 2‐(4‐oxo‐4H‐1‐benzopyran‐3‐yl)‐4‐thiazolidinones by microwave‐assisted one‐pot parallel syntheses

A one‐pot liquid‐phase combinatorial synthesis of 2‐(4‐oxo‐4H‐1‐benzopyran‐3‐yl)‐4‐thiazolidinones bearing diverse substituents at the 3‐position under microwave irradiation was successfully performed using 3‐formyl chromone, primary amine, and mercaptoacetic acid as reactants. Compared to an identical library generated by conventional parallel synthesis, the microwave‐assisted parallel synthesis approach dramatically decreased the reaction time from an average of 9 h to 5 min, and substantially increased the product yields. The coupling of microwave technology with liquid‐phase combinatorial synthesis constitutes a novel and particularly attractive avenue for the rapid generation of structurally diverse libraries. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:381–389, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20309     

An Elegant Synthesis of a New Class of 1‐(Substituted)‐1H‐1,2,3‐triazol‐4‐yl)methyl)diphenylphosphineoxides by Microwave Irradiation

A simple and efficient one‐pot microwave‐assisted click formation of 1‐(substituted)‐1H‐1,2,3‐triazol‐4‐yl)methyl)diphenylphosphineoxide derivatives via Huisgen regioselective [3+2]‐cycloaddition of an in situ generated organic azides and diphenyl(prop‐2‐yn‐1‐yl)phosphine oxide in highly polar DMSO‐H₂O medium. This synthetic protocol is mild, requires shorter reaction time, and afforded products in excellent yields with high regioselectivity.     

[BMIM]Cl Catalyzed One‐Pot Synthesis of α‐Aminophosphonate Derivatives Containing a 4‐Phenoxyquinazoline Moiety under Microwave Irradiation

[BMIM]Cl catalyzed three component Mannich‐type reaction of 4‐(quinazolin‐4‐yloxy)benzenamine and aldehyde with dialkyl phosphite under microwave irradiation has been described. The salient features of the reaction leading to new α‐aminophosphonates include shorter reaction time and good yields. The method is environmentally friendly and does not require toxic catalysts or solvents. To the best of our knowledge, this is the first report for [BMIM]Cl induced one‐pot synthesis of α‐aminophosphonate derivatives.     

Microwave-accelerated Synthesis of Some (±)-1-Aryl-5-chloroisochromans

Solventless one-pot synthesis of some new (±)-1-aryl-5-chloroisochromans by cyclocondensation of 2-(2-chlorophenyl)ethanol with aromatic aldehydes via an acid catalyzed oxa-Pictet-Spengler reaction under microwave irradiation is described.     

Rapid synthesis of 2,5‐disubtituted 1,3,4‐thiadiazoles under microwave irradiation

The one pot, three‐components condensation of aromatic aldehydes, hydrazine and sulfur in ethanol under microwave irradiation provided symmetrically 3,5‐disubstituted 1,3,4‐thiadiazoles in high yields and good purity. This reaction must be conducted under pressure of hydrogen sulfide produced in‐situ. The structure of the compounds was confirmed by ¹H, ¹³C NMR, MS and elemental analysis.     

BTADCI Promoted One‐pot Synthesis of 14‐aryl‐14H‐dibenzo [a,j] Xanthenes

A convenient eco‐friendly one‐pot synthesis of 14‐aryl‐14H‐dibenzo [a, j] xanthenes were developed by the condensation of aromatic aldehydes and β‐naphthol with BTADCI (Benzyltrimethylammonium dichloroiodate) as catalyst under solvent free conditions and microwave irradiation with much more rate accelerations and afford very good yields. Developed protocols involve mild reaction conditions, simple isolation of derivatives with inexpensive reagents.     

One‐Pot Microwave‐Assisted Synthesis of Novel Substituted N‐Dichloroacetyl‐4,5‐dimethyl‐1,3‐oxazolidines

A one‐pot and efficient synthesis of substituted N‐dichloroacetyl‐4,5‐dimethyl‐1,3‐oxazolidines utilizing the reaction of alkamine with aldehyde or ketone in refluxing benzene under microwave irradiation was described. The N‐acylation was followed with dichloroacetyl chloride and NaOH acting as the attaching acid agent. All compounds were characterized by IR, ¹H NMR, ¹³C NMR, and element analysis. Additionally, the absolute configuration of 4a was determined by X‐ray crystallography. All the compounds were tested for their herbicide safeners activity of protecting the maize from the injury of acetochlor.     

Novel synthesis of 3‐phenylazo‐1,5‐benzothiazepines, ‐1,5‐benzoxazepines and ‐1,5‐benzodiazepines via a one‐pot reaction

Novel polysubstituted ‐1,5‐benzothiazepine, ‐1,5‐benzoxazepine, and ‐1,5‐benzodiazepine were prepared in good yields by the reaction of hydrazono derivatives with o‐thioaminophenol, o‐aminophenol and o‐phenylenediamine via a one‐pot reaction.     

An efficient one‐pot synthesis of 5‐aryl substituted 2‐amino‐5,8‐dihydropyrido[2,3‐D] pyrimidin‐4,7‐diones under microwave irradiationl without catalyst

A series of 5‐aryl substituted 2‐amino‐5,8‐dihydropyrido[2,3‐d]pyrimidin‐4,7‐diones were synthesized through one‐pot condensation of 2,6‐diaminopyrimidin‐4‐one, aldehyde and Meldrum's acid using glycol as energy transfer agent under microwave irradiation without catalyst. The one‐pot protocol in the absence of catalyst has the advantage of good yield (86‐95%), short route and reaction time (3‐6 min) and environmentally friendly.     

Regioselectively Synthesis of Thiazolo[4,5‐a]acridines and Oxazolo[5,4‐a]thiazolo[5,4‐j]acridines via Multicomponent Domino Reactions

A regioselective three‐component reaction of aromatic aldehydes, 2‐hydroxy‐1,4‐naphthoquinone and benzo[d]thiazol‐5‐amine in HOAc under microwave irradiation has been developed. A series of new thiazolo‐fused benzo[h]acridines were synthesized with high chemical yields in this one‐pot reaction. The resulting thiazolo‐fused acridines were employed to further react with aldehydes and ammonium acetate to give polycyclic‐fused oxazolo[5,4‐a]thiazolo[5,4‐j]acridines. The present synthesis shows several advantages, such as operational simplicity, fast reaction rates, which makes it a useful and attractive process of library generation for drug discovery.     

Synthesis of 1,2,4‐triazolo[1,5‐d]‐1,2,4‐triazine‐5‐thiones

In an attempt to discover bicyclic compounds containing the 1,2,4‐triazine moiety, 1,2,4‐triazolo[1,5‐d]‐1,2,4‐triazine‐5‐thiones from one pot reaction of arylnitriles with 4‐amino‐1,2,4‐triazine‐3‐thione‐5‐one in the presence of potassium tert‐butoxide were synthesized.     

A One‐Pot Synthesis of 3‐Amino‐1H‐isoindol‐1‐one thiazol‐2‐ylhydrazones

A reaction of phthalonitrile with thiosemicarbazide and α‐haloketones proceeded in one‐pot, giving rise to 3‐amino‐1H‐isoindol‐1‐one thiazol‐2‐ylhydrazones in high yields.     

Convenient Synthesis of 14‐Aryl‐14‐H‐dibenzo[a,j]xanthenes Catalyzed by Acyclic Brønsted Acidic Ionic Liquid [H—NMP]+[HSO4]− under Microwave Irradiation

Efficient method for direct preparation of 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes through condensation of β‐naphthol with various aromatic aldehydes in the presence of the catalytic amount of [H—NMP]⁺[HSO₄]^? under microwave irradiation was described. This method has the advantages such as; very easy reaction workup, absolute separation of catalyst from the reaction mixture and smooth recyclability of catalyst. In this reaction 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes were obtained as desired products in excellent yields and short reaction times via green and one‐pot procedure.     

Efficient One‐Pot Synthesis of Spiro[indoline‐3,1′‐pyrazolo[1,2‐b] phthalazine] Derivatives via Three‐Component Reaction

An efficient one‐pot synthesis of spiro[indoline‐3,1′‐pyrazolo[1,2‐b]phthalazine] derivatives via three‐component reaction of phthalhydrazide, isatin, and malononitrile (cyanoacetic ester) is described. This new protocol has the advantages of high efficiency, mild reaction conditions, one‐pot procedure, and convenient operation.     

InCl3 Promoted Synthesis of Pyrano[3,2‐h]quinolines via Microwave Irradiation

An efficient and economical method has been developed for the synthesis of pyrano[3,2‐h]quinolines via an indium trichloride‐catalyzed one‐pot three‐component reaction of 8‐hydroxyquinoline with aromatic aldehydes and malononitrile/ethyl cyanoacetate under microwave irradiation.     

Synthesis of Dialkyl 2‐(Alkylamino)‐4,9‐dihydro‐9‐oxocyclohepta[b]pyran‐3,4‐dicarboxylates

Dialkyl 2‐(alkylamino)‐4,9‐dihydro‐9‐oxocyclohepta[b]pyran‐3,4‐dicarboxylates are prepared in a one‐pot three‐component reaction of alkyl isocyanide, dialkyl acetylenedicarboxylate, and α‐tropolone (=2‐hydroxycyclohepta‐2,4,6‐trienone). The reaction proceeds smoothly at room temperature and under neutral conditions to afford tropolone derivatives in high yield.     

New Convenient Five‐Component One‐Pot Synthesis of 3‐Alkyl‐6‐amino‐1,4‐dihydro‐4‐{[(1,2,3‐triazol‐4‐yl)methoxy]phenyl}pyrano[2,3‐c]pyrazole‐5‐carbonitrile Derivatives

3‐Alkyl‐6‐amino‐1,4‐dihydro‐4‐{[(1,2,3‐triazol‐4‐yl)methoxy]phenyl}pyrano[2,3‐c]pyrazole‐5‐carbonitrile derivatives were synthesized through a one‐pot five‐component condensation reaction.