Catalyst‐free one‐pot regioselective synthesis of benzo[d]imidazo[2,1‐b]thiazoles by heating or grinding

Eco‐friendly, efficient, and simple one‐pot catalyst‐free new procedures have been reported for the synthesis of benzo[d]imidazo[2,1‐b]thiazoles by condensation of phenylglyoxal, cyclic enolizable carbonyl compounds, and 2‐aminobenzothiazole at 80°C or by grinding the components at room temperature in glycerol. Cyclic enolizable carbonyl compounds employed in the protocol include dimedone, cyclohexa‐1,3‐dione, cyclopenta‐1,3‐dione, 5‐methylcyclohexa‐1,3‐dione, and 4‐hydroxy‐6‐methyl‐2‐pyrone. All the reactions were complete in ~30 min. The structures of all the products were confirmed by spectral data. The structures of compounds IVl and IVe have also been confirmed by X‐ray crystallographic studies. This protocol offers advantages such as short reaction time, easy workup, high yields and an environmentally benign methodology.     

A Rapid and an Efficient Route to the One‐pot,Multicomponent Synthesis of 1H‐Pyrazolo[1,2‐b]phthalazine‐5,10‐dione Ring Systems

CAN is found to be an efficient catalyst for the synthesis of 1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione derivatives via one‐pot coupling reaction of phthalhydrazide, aromatic aldehydes, and malononitrile or ethyl cyanoacetate in PEG as solvent. The major attributes of this synthetic protocol are the use of nontoxic, inexpensive, and readily available catalyst, mild conditions, easy work up, improved yields, and the PEG 400 as solvent that is environmentally benign as well as recyclable.     

N,N‐dimethylamino‐functionalized basic ionic liquid catalyzed one‐pot multicomponent reaction for the synthesis of 4H‐benzo[b]pyran derivatives under solvent‐free condition

A simple, clean, and environmentally benign three‐component process for the synthesis of 4H‐benzo[b]pyran derivatives using basic ionic liquid N,N‐dimethylaminoethylbenzyldimethylammonium chloride ([PhCH₂Me₂N⁺CH₂CH₂NMe₂]Cl⁻) as an efficient catalyst under solvent‐free condition is described. A wide range of aromatic aldehydes easily undergoes condensation with malononitrile and 5,5‐dimethylcyclohexane‐1,3‐dione (dimedone) under solvent‐free condition to afford the desired products of good purity in excellent yields. Taking into account environmental and economical considerations, the protocol presented here has the merits of environmentally benign, simple operation, convenient workup, and good yields. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:91–94, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20516     

Three‐Component Uncatalyzed Eco‐Friendly Reactions for One‐Pot Synthesis of 4,7‐Dihydro[1,2,4]triazolo[1,5‐a]pyrimidine Derivatives

A three‐component system of one‐pot synthesis of [1,2,4]triazolo[1,5‐a]pyrimidine derivatives using condensation of 1,3‐dicarbonyl compounds, aldehydes, and 5‐amino[1,2,4]triazole in ethanol without any catalyst was reported in high yields via simple, efficient, and environmentally friendly process. The method reported herein considered a green process; this method has significant advantages of simple workup procedure, excellent yield, minimal environmental pollution, and short reaction time over classical reported methods.     

Three‐component one‐pot synthesis of pyrazolo[3,4‐b]quinolin‐5(6H)‐one derivatives in aqueous media

A series of 4‐aryl‐3,7,7‐trimethyl‐1‐phenyl‐7,8‐dihydro‐1H‐pyrazolo[3,4‐b]quinolin‐ 5(6H)‐ones were synthesized by the three‐component reaction of aromatic aldehydes, 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐amine, and 5,5‐dimethyl‐1,3‐cyclohexandione in the presence of sodium 1‐dodecanesulfonate in aqueous medium. Compared to the previous methods, this new protocol has the advantages of convenient operation, higher yields, lower cost, and environmentally benign procedure. J. Heterocyclic Chem., (2012).     

A Green Method for the Synthesis of Cyclopenta[b]chromen‐1(9H)‐one Derivatives in Ionic Liquids

A series of cyclopenta[b]chromen‐1(9H)‐one derivatives is prepared in high yields by a one‐pot reaction of substituted salicylaldehydes and cyclopentane‐1,3‐dione in ionic liquids of [BMIm]Br, the procedure is very mild and environmentally benign.     

An efficient synthesis of pyrazolo[3,4‐b]quinolin‐5(6H)‐one derivatives in ionic liquid

A series of 4‐aryl‐3,7,7‐trimethyl‐1‐phenyl‐7,8‐dihydro‐1H‐pyrazolo[3,4‐b]quinolin‐5(6H)‐ones were synthesized via the three‐component reaction of aromatic aldehydes, 5,5‐dimethyl‐1,3‐cyclohexandione and 5‐amino‐3‐methyl‐1‐phenylpyrazole in ionic liquid without using any catalyst. This protocol has the advantages of easier work‐up, milder reaction conditions, short reaction time, and environmentally benign procedure. J. Heterocyclic Chem., (2011).     

ZrOCl2·8H2O as an efficient and recyclable catalyst for the one‐pot multicomponent synthesis of novel [1,3]oxazino[5,6‐c]quinolin‐5‐one derivatives

A simple, efficient and eco‐friendly procedure has been developed using ZrOCl₂·8H₂O as catalyst for the synthesis of novel [1,3]oxazino[5,6‐c]quinolin‐5‐one derivatives in aqueous ethanol at room temperature. The present methodology offers several advantages such as operational simplicity, use of ZrOCl₂·8H₂O as a green, non‐toxic, inexpensive and reusable catalyst, reusability of reaction media, high yields, mild and environmentally benign reaction conditions.     

One‐pot Three‐component Synthesis of Spiro[pyrazolo[3,4‐b]pyridine‐4,3′‐indoline] Derivatives Catalyzed by Melamine Trisulfonic Acid

Novel spiro[pyrazolo[3,4‐b]pyridine‐4,3′‐indoline] derivatives were prepared by the three‐component reaction of isatins 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐amine and Meldrum's acid in the presence of a catalytic amount of melamine trisulfonic acid. This protocol provides a simple one‐step procedure with the advantages of easy work‐up, mild reaction conditions and environmentally benign.     

One‐Pot Synthesis of 3‐[(N‐Alkylanilino)(aryl)methyl]indoles via a Transition Metal Assisted Three‐Component Condensation at Room Temperature

A simple and highly efficient protocol for the one‐pot synthesis of a series of 3‐[(N‐alkylanilino)(aryl)methyl]indoles has been developed based on low‐cost and environmentally benign zirconium oxychloride octahydrate and copper chloride dihydrate catalysts via three‐component condensation between indoles, aromatic aldehydes, and N‐alkylanilines at room temperature under neat condition. Mild reaction conditions, operational simplicity, high atom‐economy, good yields in relatively shorter reaction times, use of low‐cost and eco‐friendly catalysts are some of the salient features of this protocol.     

Facile Methods for the Synthesis of 5‐Aryl and 5‐Iodo Pyrrolo[2,3‐d]pyrimidines

An efficient and environmentally benign one‐pot method has been developed for the synthesis of 4‐amino‐5‐arylpyrrolo[2,3‐d]pyrimidines. Phthalimido acetophenones were reacted with cyanoacetamide to give 2‐amino‐4‐phenyl‐1H‐pyrrole‐3‐carboxamides, which were further converted to 5‐aryl‐3H‐pyrrolo[2,3‐d]pyrimidin‐4‐ones. A novel method is also developed for the synthesis of 4‐amino‐5‐iodopyrrolo[2,3‐d]pyrimidines.     

Methanesulfonic Acid‐Catalyzed One‐Pot Synthesis of 12‐Aryl or 12‐Alkyl‐8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one Derivatives

An efficient synthesis of 12‐aryl or 12‐alkyl‐8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one derivatives has been developed under solvent‐free conditions by one‐pot condensation of aldehydes, 2‐naphthol, and cyclic 1,3‐dicarbonyl compounds in the presence of a catalytic amount of methanesulfonic acid. The protocol has advantages of mild condition, short reaction time, high yield, and operational simplicity.     

A Catalyst‐free Green Protocol for the Synthesis of Pyranopyrazoles Using Room Temperature Ionic Liquid Choline Chloride‐urea

An efficient and rapid four component reaction of aldehydes, malanonitrile, β‐ketoesters and hydrazine hydrate (or phenyl hydrazine) in environmentally benign room temperature ionic liquid choline chloride‐urea has been developed for the synthesis of substituted 4H‐pyrano[2,3‐c]pyrazoles.     

One‐Pot Three‐Component Domino Reaction for the Synthesis of Novel Spiro Indolinyl Isoxazolo[2,3‐c][1,3,5]Thiadiazepinones Catalyzed by PTSA

The synthesis of novel spiro indolinyl isoxazolo[2,3‐c] [1,3,5]thiadiazepinones has been achieved by using one‐pot three‐component domino reaction from 3‐amino‐5‐methylisoxazole, substituted isatins, and mercapto acetic acid by employing p‐toluene sulfonic acid as Lewis acid catalyst. The salient features of the present method are mild reaction conditions, cost effective, environmentally benign, high yields of products and operational simplicity.     

A One‐pot,Efficient Synthesis of Polyfunctionalized Pyrido[2,3‐d]pyrimidines and Uncyclized Adducts by Aldehydes, 1,3‐Dicarbonyl Compounds,and 6‐Aminouracils

A one‐pot, efficient protocol for the synthesis of polyfunctionalized pyrido[2,3‐d]pyrimidines and uncyclized adducts by 6‐aminouracils in poly(ethylene glycol) 200/H₂O or AcOH was described. An interesting family of pyrido[2,3‐d]pyrimidines and uncyclized adducts bearing fused pharmacological active units are prepared. The reaction is free of toxic solvents and catalysts, has simple workup procedure, and has high atom economy, making it more environmentally friendly and suitable for large‐scale operations.     

Microwave‐enhanced Efficient Synthesis of Some Polyfunctional Pyridazines

Microwave‐enhanced highly efficient protocol for the synthesis of polyfunctional pyridazines beginning from 3,6‐dichloropyridazine in environmentally benign ionic liquids have been developed. The products obtained were 3‐amino‐6‐chloropyridazine, 3,6‐diaminopyridazine, and 3‐chloro‐6‐methoxypyridazine. These derivatives were then be converted to a variety of polyfunctional pyridazine derivatives. The ionic liquids used were 1‐n‐butyl‐3‐methylimidazolium hydroxide/tetrafluoroborate/hexafluorophosphate and 1,3‐di‐n‐butylimidazolium hydroxide. This powerful strategy is less time‐consuming green methodology. The ionic liquid employed may be recovered and recycled.     

An Efficient synthesis of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives via multicomponent reactions in ionic liquid

A series of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives were synthesized via the three‐component reaction of an aldehyde, 6‐aminopyrimidine‐2,4‐dione and 5,5‐dimethyl‐1,3‐cyclohexanedione or 1,3‐indanedione in ionic liquid 1‐n‐butyl‐3‐methylimidazolium bromide ([bmim]Br). This protocol has the advantages of easier work‐up, milder reaction conditions, high yields and an environmentally benign procedure compared with other methods.     

Simple and Clean Procedure for Three‐Component Syntheses of Spiro{pyrido[2,1‐b]benzothiazole‐3,3′‐indolines} and Spiro{thiazolo[3,2‐a]pyridine‐7,3′‐indolines} in Aqueous Medium

A simple and efficient one‐pot three component synthesis of spiro{pyrido[2,1‐b]benzothiazole‐3,3′‐indoline} and/or spiro{thiazolo[3,2‐a]pyridine‐7,3′‐indoline} derivatives were carried out by the reaction of 2‐mercaptoaniline and/or mercaptoacetic acid, malononitrile, and a series of 2‐oxoindoline‐3‐ylidines in aqueous medium. This method is of great value because of its environmentally benign character, high yield processing, and easy handling.     

Preparation and characterization of new inorganic–organic hybrid catalyst H3PMo12O40/Hyd‐SBA‐15 and its application in the domino multi‐component reaction

We present novel inorganic–organic hybrid catalyst to accomplish domino multi‐component reaction (MCR) for synthesis of 3‐amino‐2′‐oxospiro[benzo[c]pyrano[3,2‐a]phenazine‐1,3′‐indoline]‐2‐carbonitrile/carboxylate derivatives. This methodology offers remarkable development by easy production of H₃PMo₁₂O₄₀/Hyd‐SBA‐15 in regard to solving the problem of using harsh catalysts, also it demonstrates to be impressive and environmentally friendly in term of low reaction times and high yields.     

Diversified Synthesis of Furans by Coupling between Enols/1,3‐Dicarbonyl Compounds and Nitroolefins: Direct Access to Dioxa[5]helicenes

A versatile method for the diversified synthesis of furans and arenofurans has been developed that proceeds through K₂CO₃‐promoted cyclization between enols/1,3‐dicarbonyl compounds and nitroolefins at reflux in EtOH. This facile method has been successfully employed in the synthesis of benzotrifuran derivatives, which are useful hole‐transporting materials. This procedure also provides direct access to dioxa[5]helicenes. This reaction offers a broad substrate scope, uses an inexpensive base and environmentally benign solvent, and is operationally simple.