Catalyst-free synthesis of novel 4H-indeno[1,2-b]furan-4-ones and furo[2,3-d]pyrimidines in water

An operationally simple, catalyst-free, and efficient protocol for the synthesis of novel 4H-indeno[1,2-b]furan-4-one and furo[2,3-d]pyrimidine derivatives by a one-pot reaction of 2-aminopyridines, 1,3-indandione, or barbituric acid and phenylglyoxal monohydrate in water at reflux, involving domino aldol condensation, Michael addition, and ring-closing reactions is described. This transformation has several advantages, including high yield, short reaction duration, simple workup, and simple purification.     

Convenient and Efficient One-Pot Method for the Synthesis of 2-Amino-tetrahydro-4H-chromenes and 2-Amino-4H-benzo[h]-chromenes Using Catalytic Amount of Amino-Functionalized MCM-41 in Aqueous Media

A convenient and efficient one-pot method for the synthesis of 2-amino-tetrahydro-4H-chromene and 2-amino-4H-benzo[h]-chromene derivatives has been developed using a catalytic amount of amino-functionalized MCM-41 in aqueous medium. This efficient technique has the advantages of giving 4H-tetrahydro-chromene and 4H-benzo[h]chromene building blocks using a reusable catalyst in good to excellent yields, to be completed in short reaction times with a simple product isolation procedure.     

Sustainable synthesis of [1]benzopyran azo dyes using CuCr2O4 NPs

In this study, copper chromite nanoparticles (CuCr₂O₄ NPs) were prepared by a simple hydrothermal method. This nanomaterial was found as an efficient heterogeneous catalyst for the synthesis of a new class of [1]benzopyran azo dyes via pseudo-three-component reaction of (E)-1,2-diphenyl-1-diazene with 4-hydroxycoumarin in the ratio 1:2. The aim of the present work was to provide a practical and high yielding protocol that offers several advantages such as simple procedure with an easy work-up, mild reaction conditions, and the use of CuCr₂O₄ NPs as an efficient and easily recoverable catalyst.     

ZrCl4/[bmim]BF4‐catalyzed condensation of salicylaldehydes and malononitrile: Single‐step synthesis of 3‐cyanocoumarin derivatives

A versatile and efficient single‐step route to 3‐cyanocoumarins via Knoevenagel condensation of salicylaldehydes and malononitrile using ZrCl₄ as the catalyst (15 mol %) in ionic liquid 1‐(n‐butyl)‐3‐methylimidazolium tetrafluoroborate as reaction medium and catalyst is described. The novel procedure features single step, short reaction time, good yields, and simple workup. J. Heterocyclic Chem., (2011).     

Three-component reaction for synthesis of 2-amino-6-aryl-5-(phenylamino)-3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-one derivatives in water

A new three-component domino reaction for the synthesis of 2-amino-6-aryl-5-(phenylamino)-3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-one derivatives 4 using acetic acid as catalyst has been established. The reaction was performed in aqueous media using readily available and inexpensive 2,6-diaminopyrimidin-4(3H)-one 1 , 2,2-dihydroxy-1-arylethan-1-one 2 and aniline 3 as substrates. The simple and efficient one-pot three-component approach, inexpensive catalyst, green reaction media, make the present methodology a good synthetic procedure.     

Zr(HSO4)4‐catalyzed one‐pot three‐component synthesis of 7‐alkyl‐6H,7H‐naphtho[1′,2′:5,6]pyrano[3,2‐c]chromen‐6‐ones

A new, one‐pot, simple thermally efficient and solvent‐free method for the preparation of 7‐alkyl‐6H,7H‐naphtho[1′,2′:5,6]pyrano[3,2‐c]chromen‐6‐ones by condensation of β‐naphthol, aromatic aldehydes, and 4‐hydroxycoumarin using Zr(HSO₄)₄ as a safe and efficient catalyst is described. This method has the advantages of high yields, a cleaner reaction, simple methodology, short reaction times, easy workup, and greener conditions. J. Heterocyclic Chem., (2011).     

An Efficient and Simple Method for Diazotization-Thiocyanation of Aryl Amine using Cross-Linked Poly (4-Vinylpyridine) Supported Thiocyanate Ion

Abstract

An efficient and simple method for the facile synthesis of arylthiocyanates via diazotization-thiocyanation of aryl amines using cross-linked poly (4-vinylpyridine) supported thiocyanate ion is described. Various primary aromatic amines, with electron-withdrawing and electron-donating groups, were transformed into aryl thiocyanates in high to excellent yields in a short reaction time. The present procedure offers advantages such as short reaction time, simple reaction work-up, and the polymeric reagents can also be regenerated and reused for several times without significant loss of their activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Sodium Formate‐Catalyzed One‐Pot Synthesis of Benzopyranopyrimidines and 4‐Thio‐substituted 4H‐Chromenes via Multicomponent Reaction at Room Temperature

A simple, straightforward and highly efficient multicomponent one‐pot synthesis of a series of pharmaceutically interesting benzopyranopyrimidine and 4H‐chromene derivatives has been developed on the basis of low‐cost and environment‐friendly sodium formate catalyst via tandem reactions of salicylic aldehydes, malononitrile, and cyclic secondary amines in ethanol at room temperature. Nature of nucleophile used in this reaction directs the course of the reaction; cyclic secondary amines result in the formation of benzopyrano[2,3‐d]pyrimidines, whereas thiophenol furnish corresponding 4‐thio‐subtituted 4H‐chromenes under the same reaction conditions. High atom‐economy, good yields, eco‐friendly, and mild reaction conditions are some of the important features of this protocol.     

An Efficient and Facile Synthesis of tert‐Butyl 2‐(Methylamino)‐3‐nitro‐5‐oxo‐4‐aryl‐7,8‐dihydro‐4H‐pyrano[3,2‐c]pyridine‐6(5H)‐carboxylate derivatives in [BMIM]BF4

In this research, we have developed an efficient three‐component reaction for the synthesis of pyrano[3,2‐c]pyridine derivatives from the reaction of aromatic aldehydes, tert‐butyl 2,4‐dioxopiperidine‐1‐carboxylate, and N‐methyl‐1‐(methylthio)‐2‐nitroethylen‐1‐amine in [BMIM]BF₄ medium. The advantages of this method were readily available starting materials, simple reaction conditions, and satisfactory yields.     

Catalytic Thiourea Promoted Electrophilic Thiocyanation of Indoles and Aromatic Amines with NCS/NH4SCN

A simple and efficient protocol for the electrophilic thiocyanation of indoles and aromatic amines with thiourea/NCS/NH₄SCN system has been developed. The major features of the present procedure are the mild conditions, good yields, short reaction times, and the use of inexpensive and readily available organocatalyst. Moreover, N‐chlorosuccinimide (NCS) was found to be indispensable, and thiourea could greatly promote the reaction.     

Cation-exchange resin as an efficient hetero-geneous catalyst for one-pot three-component synthesis of 2,3-dihydro-4(1H)-quinazolinones

Various mono- and disubstituted 2,3-dihydro-4(1H)-quinazolinones were synthesized efficiently by a one-pot three-component condensation of isatoic anhydride, aromatic aldehydes, and ammonium salts or primary amines using a strong acidic cation-exchange resin as the catalyst in EtOH–H₂O solution. The catalyst is cheap, efficient, stable, and reusable under the reaction conditions. The novel method offers several advantages, such as excellent yields, environmentally friendly reaction media, and simple procedure.     

Zinc‐Catalyzed [4+3] Cycloaddition with Concomitant Furan Annulation: Formation of Cyclohepta[b]Furans

A convenient zinc‐promoted [4+3] cycloaddition of a carbonyl ene–yne with simple dienes was first achieved. This reaction provided an efficient strategy to prepare various cyclohepta[b]furan rings by cascade cycloadditions. Additionally, a multicomponent reaction of dione, alkynal, and diene was also reported, which exhibited a novel strategy for selective creations of C?O bonds and C?C bonds.     

ZrCl4/TMSCl as an Efficient Catalyst for Synthesis of 4,6‐Substituted 2‐Alkylthio‐6H‐1,3‐thiazines

4,6‐Substituted‐2‐alkylthio‐6H‐1,3‐thiazines were synthesized by the reaction of S‐alkyl dithiocarbamates and α, β‐unsaturated ketones in the presence of ZrCl₄/TMSCl. The procedure is simple and efficient and gives good to high yields of products.     

Convenient and Efficient Method for the Iodination of Benzylic and Aliphatic Alcohols by Using Al(HSO4)3/KI in Nonaqueous Solution

A simple and efficient method for the iodination of benzylic and aliphatic alcohols by using Al(HSO₄)₃/KI in n‐hexane as solvent is reported. Mild reaction conditions and good to excellent yields of the products are the noteworthy advantages of the method.     

Microwave Assisted Green Multicomponent Synthesis of Novel bis(2‐Amino‐tetrahydro‐4H‐chromene‐3‐carbonitrile) Derivatives Using Chitosan as Eco‐friendly Basic Catalyst

A simple, efficient, and eco‐friendly procedure has been developed for the synthesis of bis(4H‐chromene‐3‐carbonitrile) derivatives using chitosan as catalyst under microwave‐assisted reaction conditions. For the sake of comparison, the reaction was also carried out under conventional heating in the presence of each of chitosan and piperidine as basic catalysts.     

Asymmetric Reduction of α‐Amino Ketones with a KBH4 Solution Catalyzed by Chiral Lewis Acids

An efficient enantioselective reduction of α‐amino ketones with potassium borohydride solution catalyzed by chiral N,N′‐dioxide–metal complex catalysts was accomplished under mild reaction conditions for the first time. It provided a simple, convenient, and practical approaches for obtaining synthetically important chiral β‐amino alcohols in good to excellent yields (up to 98 %) and enantioselectivities (up to 97 % ee).     

An efficient synthesis of 2,3‐dihydroquinazolin‐4(1H)‐one derivatives under catalyst‐free and solvent‐free conditions

A simple, efficient and convenient one‐pot synthesis of 2,3‐dihydroquinazolin‐4(1H)‐one derivatives under solvent‐free and catalyst‐free conditions by the reaction of aromatic aldehydes, isatoic anhydride, and ammonium acetate was reported. The advantages of this protocol include short reaction time, mild reaction conditions, easy work‐up, high yields, and environmental friendliness. J. Heterocyclic Chem., (2011).     

2-Aminoethanesulfonic acid: An efficient organocatalyst for green synthesis of spirooxindole dihydroquinazolinones and novel 1,2-(dihydroquinazolin-3(4H)isonicotinamides in water

Abstract

A facile and efficient one-pot procedure for the preparation of spirooxindole dihydroquinazolinone derivatives and new N-(4-oxo-2-phenyl-1,2-dihydroquinazolin-3(4H)-yl)isonicotinamides from reaction between isatoic anhydride, isoniazid and substituted aldehydes catalyzed by 2-aminoethanesulfonic acid (taurine) is describe. This new protocol has the advantages of environmental friendliness, good yields, and convenient operation. The reaction proceeds efficiently using water as green solvent and nontoxic catalysts that could be efficiently reused. Together with this simple workup procedure, use of the organocatalyst, and water as solvent without the need of column chromatographic purification, are the notable features of this methodology, which make this protocol a very efficient and green alternative to the traditional methods.     

Highly Efficient Synthesis of Substituted Benzenes in the Presence of B(HSO4)3 as a New and Reusable Catalyst Under Solvent-Free Conditions

A highly efficient and simple procedure for the synthesis of substituted benzenes is described. A broad range of ketones (alkyl–aryl ketones and cyclic ketones) were condensed via a cyclotrimerization reaction in the presence of catalytic amounts of boron sulfonic acid [B(HSO₄)₃], a new, highly efficient, and reusable catalyst, under solvent-free conditions. All reactions completed in short times without formation of any by-products. The catalyst was recovered and reused successfully for 15 cycles of the reaction.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Synthesis of pyrano[2,3‐c]pyrazole derivatives using Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate (Fe3O4@SiO2 nanoparticle‐supported IL) as a novel,green and heterogeneous catalyst

A simple, green and efficient protocol for the one‐pot four‐component synthesis of pyrano[2,3‐c ]pyrazole derivatives produced from reaction between aryl aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of nano magnetic piperidinium benzene‐1,3‐disulfonate was synthesized in water at 60 °C. The Fe₃O₄@SiO₂ nanoparticle‐supported IL was designed and synthesized. The present process offers advantages such as clean reaction, short reaction time, good to excellent yield, easy purification and easy recoverable catalyst.