A metal-free C–C/C–O bond formation for the synthesis of 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carboxamide catalyzed by polystyrene-supported p-toluenesulfonic acid (PS-PTSA)

An efficient and eco-friendly procedure for the synthesis of 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carboxamide has been developed through a one-pot three-component condensation of 4-hydroxycoumarin with aldehydes and cyanoacetamide, in the presence of catalytic amount of polystyrene-supported p-toluenesulfonic acid (PS-PTSA) as a highly active and reusable heterogeneous acid catalyst in EtOH at 80?°C conditions. This new procedure offers several advantages such as shorter reaction times, excellent yields, a wide range of functional group tolerance, easy experimental work-up procedure, operationally simple under metal-free reaction conditions and C-C/C-O bond formation. The catalyst can be recovered and reused for at least four runs without any significant impact on the product yields.     

Basic Functionalized Ionic Liquid Catalyzed One-pot Mannich-type Reaction: Three Component Synthesis of β-Amino Carbonyl Compounds

Summary. Three-component Mannich-type reaction of cyclohexanone, aromatic aldehydes, and aromatic amines was catalyzed by a basic functionalized ionic liquid, 1-butyl-3-methylimidazolium hydroxide ([bmim][OH]), at room temperature to give various β-amino carbonyl compounds in high yields. The ionic liquid, which is environmentally friendly, can be recycled at least 5 times without significant loss of activity.     

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.     

Microwave Synthesis of 5-Substituted 1H-Tetrazoles Catalyzed by Bismuth Chloride in Water

Bismuth chloride was used to catalyze the [2 + 3] cycloaddition between sodium azide with aryl nitriles, aliphatic nitriles, and vinyl nitriles. A number of 5-substituted 1H-tetrazoles were synthesized in water or isopropanol/water mixtures using microwave heating. Good yields were obtained for these reactions when heated for 1 h at 120–160 °C in a 3:1 isopropanol/water mixture. A few of the less reactive nitriles required longer reaction times for good yields.     

Chitosan-SO3H (CTSA) an efficient and biodegradable polymeric catalyst for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol) and α-amidoalkyl-β-naphthol’s

Abstract

An efficient, green procedure for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol) and α-amidoalkyl-β-naphthol’s using biodegradable polymeric catalyst chitosan-SO₃H (CTSA), is operationally easy to prepare by mixing chitosan and chlorosulfonic acid. This catalyst displays excellent catalytic activity and reusable for five subsequent reactions without significant loss of catalytic activity. This protocol proceeds with short reaction times, at mild temperatures, in a solvent-free reaction, and generally with high yields. We present herein a practical, efficient and simple procedure with a broad substrate scope that allows access to two different reactions 1H-pyrazole-5-ol and α-amidoalkyl-β-naphthol’s core unit.     

An eco-friendly procedure for the efficient synthesis of arylidinemalononitriles and 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) in aqueous media

Abstract

Commercially available lithium hydroxide monohydrate (LiOH·H₂O) was found to be a novel “dual activation” catalyst for Knoevenagel condensation between malononitrile (1) or 3-methyl 1-phenyl-1H-pyrazol-5-(4H)-one (6) with aromatic aldehydes 2a–e leading to an efficient and easy synthesis of arylidenemalononitriles 3a–d and 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) 7a–c in short times. The reaction of aryl aldehydes with malononitrile afforded excellent yields after 1–6 min in aqueous media at room temperature. In case of 3-methyl-1-phenyl-1H-pyrazol-5-(4H)-one (6) and aromatic aldehydes afforded good yields after 60–75 min at 90°C.     

Practical one-pot synthesis of 5-alkynyl-1,2,3-triazoles via heterogeneous copper(I)-catalyzed tandem three-component click/alkynylation reaction

An efficient and practical route to 5-alkynyl-1,2,3-triazoles has been developed via heterogeneous tandem CuAAC/alkynylation reaction of organic azides, alkynes and 1-bromoalkynes by using an L-proline-functionalized MCM-41-anchored copper(I) complex [L-Proline-MCM-41-CuCl] as catalyst under mild conditions. The reaction produces a wide variety of 5-alkynyl-1,2,3-triazoles in mostly good to excellent yields. The new immobilized copper(I) complex can be readily prepared from commercially available and inexpensive reagents and displays the same catalytic activity as CuCl. The L-Proline-MCM-41-CuCl catalyst is also easy to recover via a simple filtration process and can be reused at least seven times without apparent loss of activity.     

Facile one‐pot synthesis of a series of 7‐aryl‐8H‐benzo[h]indeno[1,2‐b]quinoline‐8‐one derivatives catalyzed by cellulose‐based magnetic nanocomposite

A sulfonated magnetic cellulose‐based nanocomposite was applied as an efficient, inexpensive and green catalyst for the one‐pot three‐component synthesis of 7‐aryl‐8H ‐benzo[h ]indeno[1,2‐b ]quinoline‐8‐ones starting from 1,3‐indanedione, aromatic aldehydes and 1‐naphthylamine under solvent‐free conditions in high yields (79–98%) within short reaction times (2–5 min). The nanobiostructure catalyst can be easily separated from the reaction mixture by using an external magnet and reused several times.     

Multicomponent reactions and supramolecular catalyst: A perfect synergy for eco-compatible synthesis of pyrido[2,3-d]pyrimidines in water

In this article, we have developed a straightforward, easy and exceedingly competent approach for the synthesis of 5-phenyl-5,6-dihydropyrido[2,3-d]pyrimidine-2,4,7(1H,3H,8H)-triones obtain in superior yields in a sole reaction pace with an air and humidity steady catalyst in water as a green solvent at 100^°C. The present procedure paves the approach for the synthesis of biologically fascinating molecular frameworks and has reward in conditions of little catalyst loading with palpable ambiguous and straightforward-to-do reaction circumstances with easy purification process. The used β-cyclodextrin catalyst was recuperated and repeated several times devoid of noteworthy loss of catalytic activity, which is a crucial parameter of green synthesis.     

Comparison of Phosphorescent Pt(II) Complexes with C^N^N vs N^N^N Chelators and Caffeine-Based NHC-co-ligands†

In this work, we explored coordination compounds featuring caffeine-based carbene co-ligands and tridentate dianionic pincer luminophores derived from 2,6-bis(1H-1,2,4-triazol-5-yl)pyridine (N), as well as from 2-phenyl-6-(1H-1,2,4-triazol-5-yl)pyridine (C), bearing either Ad (adamantyl) or tBu (tertiary butyl) substituents. The new 2-phenyl-6-(1H-1,2,4-triazol-5-yl)pyridine-based ligand precursors along with four Pt(II) complexes, namely Pt(C-tBu), Pt(C-Ad), Pt(N-tBu) and Pt(N-Ad) were characterized. Further on, the influence of the different substituents at the chelating luminophores and of the caffeine-based NHC-co-ligand on the photophysical properties (including photoluminescence quantum yields (Φ_L), excited-state lifetimes (τ), radiative (k_r), and non-radiative (k_nr) deactivation rate constants) was assessed in fluid solutions at room temperature (RT) and in frozen glassy matrices at 77 K. All four luminophores perform equivalently well within the experimental uncertainty. In deoxygenated fluid solutions at RT, photoluminescence quantum yields reaching up to 24 ± 2% and excited-state lifetimes of around 12 μs were found. The generally long excited-state lifetimes and only minor blue shift upon cooling to 77 K along with mostly well-resolved vibrational progressions point to metal-perturbed ligand-centered excited states. Notably, the yield of the complexation reaction in case of Pt(C-tBu) and Pt(C-Ad) was almost two times higher compared to Pt(N-tBu) and Pt(N-Ad). Cyclometallation is not an essential feature to achieve high photoluminescence quantum yields, but it can improve the synthetic efficiency. In summary, it can be observed that coordination chemical concepts based on natural products can lead to stable phosphorescent species with interesting excited-state properties.     

Synthesis of nitrogen-containing heterocycles. 5. A new route to 5-amino-[1,2,4]triazolo[1,5-a][1,3,5]triazine derivatives

Treatment of certain diaminomethylenehydrazones 1 of aromatic carbonyl compounds with ethyl N-cyanoimidate ( 2 ) in acetonitrile in the presence of a tertiary amine at room temperature gives the corresponding amino(N-cyanoiminomethyl)aminomethylenehydrazones 3 in high yields. The intermediate 3 can readily be cyclized to the corresponding 5-amino-2,3-dihydro[1,2,4]triazolo[1,5-a][1,3,5]triazines 4 in moderate to good yields by brief heating in acetonitrile. When the reaction of diaminomethylenehydrazones 1 with ethyl N-cyanoimidate ( 2 ) is performed at reflux temperature in the presence of a tertiary amine, 5-amino-2,3-dihydro[1,2,4]triazolo[1,5-a]1,3,5]triazines 4 can be directly obtained in moderate yields. The yields of triazolotriazine produced by the one-step synthesis are generally comparable or even higher than the overall yields from the two-step procedure.     

Green chemistry design,innovation, solutions and a cohesive system

Abstract

The green, mild, and efficient synthesis of 2, 2-dimethyl-5-[(4-oxo-4H-chromen-3-yl) methylene]-1, 3-dioxane-4, 6-diones by Knoevenagel condensation of 4-oxo-4H-benzopyran-3-carbaldehydes with Meldrum's acid in presence of 1-benzyl-3-methylimidazolium chloride ((bnmim)(Cl)) ionic liquid at room temperature is reported. This method gives remarkable advantages such as a simple procedure, mild conditions, faster (10–20 min) reactions, and excellent yields. Additionally, the (bnmim)(Cl) was successfully recycled at least four times without significant loss of activity.     

1,1,3,3‐N,N,N′,N′‐Tetramethylguanidinium Trifluoroacetate Ionic Liquid–Promoted Efficient One‐Pot Synthesis of Trisubstituted Imidazoles

Trisubstituted imidazoles have been synthesized in very short reaction times with excellent yields in the presence of 1,1,3,3‐N,N,N′,N′‐tetramethylguanidinium trifluoroacetate as an ionic liquid at 100°C. The ionic liquid can be recycled for subsequent reactions without any appreciable loss of efficiency.     

Dicationic ionic liquids as recyclable catalysts for one‐pot solvent‐free synthesis of α‐aminophosphonates

Some task‐specific ionic liquids N,N,N′,N′‐tetramethyl‐N,N′‐dipropanesulfonic acid ethylene‐diammonium hydrogen sulfate, N,N,N′,N′‐tetramethyl‐N,N′‐dipropanesulfonic acid‐1,3‐propanediammonium hydrogen sulfate, N,N,N′,N′‐ tetramethyl‐N,N′‐ dipropanesulfonic acid‐1,6‐hexanediammonium hydrogen sulfate were prepared. These ionic liquids could be used as efficient and recyclable catalysts for the synthesis of α‐aminophosphonates at room temperature via an one‐pot three‐component reaction under organic solvent‐free conditions with good yields of 83–96%. The postprocessing was simple, and the catalysts could be reused at least six times without noticeably decreasing the catalytic activity. The novel clean procedure offers the advantages including short reaction time, good yields, operational simplicity, and environmentally benign. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:1–5, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20647     

Sulfamic-acid-catalyzed simple and efficient synthesis of 4-aryl-3-methyl-1-phenyl-1H-benzo[g]pyrazolo[3,4-b]quinoline-5,10-diones under solvent-free conditions

Abstract  

An efficient synthesis of 4-aryl-3-methyl-1-phenyl-1H-benzo[g]pyrazolo[3,4-b]quinoline-5,10-diones from the three-component condensation reaction of 3-methyl-1-phenyl-1H-pyrazol-5-amine, aromatic aldehydes, and 2-hydroxy-1,4-naphthoquinone under solvent-free conditions in good to excellent yields and short reaction times using sulfamic acid as heterogeneous acid catalyst has been investigated.     

Polymer‐Supported Ionic‐Liquid‐Catalyzed Synthesis of 1,2,3,4‐Tetrahydro‐ 2‐oxopyrimidine‐5‐carboxylates via Biginelli Reaction

The Biginelli reaction between an aromatic aldehyde, ethyl acetoacetate, and urea – catalyzed by polymer‐supported, re‐usable, room‐temperature ionic liquids (RTIL) such as 1b – was shown to efficiently proceed in glacial AcOH at 100° to afford the corresponding pyrimidine‐5‐carboxylates 3 in yields up to 99% within 2 h (Table 2). The catalyst(s) could be reused at least five times, basically without loss of activity, which makes this transformation not only straight‐forward, but also considerably less expensive compared to methods involving classical RTIL catalysts.     

A Novel Catalyst‐Free One‐Pot Synthesis of Some New N‐(α‐Hydroxybenzyl)formamides by Treatment of 2,2‐Dichloroaziridines with Dimethyl Sulfoxide and Water under Neutral Conditions

A novel, mild, and efficient method is reported for the preparation of new N‐(α‐hydroxybenzyl)formamides in excellent yields and appropriate reaction times through the reaction of 2,2‐dichloroaziridines with aqueous DMSO as the O‐donor under neutral conditions at 70–85°.     

KF/Al2O3 as an Efficient,Green, and Reusable Catalytic System for the Solvent-Free Synthesis of N-Alkyl Derivatives of Sulfonamides via Michael Reactions

KF/Al ₂ O ₃ efficiently catalyzes the microwave-assisted Michael addition of sulfonamides to α,β-unsaturated esters under solvent-free conditions to afford N-alkyl derivatives of sulfonamides as biologically interesting compounds in high yields and in short reaction times. In this reaction, N,N-dialkylsulfonamides are also produced, but in very low yields.     

Synthesis of 1,1‐Diacetates using a New Combined Catalytic System: Copper p‐Toluenesulfonate/HOAc

Copper p‐toluenesulfonate acetic acid has been established as an efficient combined catalytic system for chemoselective conversion of aldehydes to diacetates in high yields at ambient temperature in short reaction times. For the catalytic system, the amount of copper p‐toluenesulfonate reduced to 0.3 mol%. After the reaction, copper p‐toluenesulfonate can be easily recovered and reused for at least 10 runs.     

Cerium‐catalyzed tandem synthesis of 2‐substituted benzothiazoles in PEG

An efficient and convenient condensation reaction of 2‐aminothiophenol with aldehydes catalyzed by a catalytic amount of ceric ammonium nitrate in polyethylene glycol was investigated. As a result, a set of diverse 2‐substituted benzothiazoles such as 2‐phenylbenzothiazole as well as its p‐Me, p‐NO₂, p‐F, p‐Cl, p‐Br, o‐OMe, p‐OMe and 2‐furyl, 2‐pyridyl and styryl derivatives were obtained in good to excellent yields for 5 h at room temperature. Additionally, the catalyst system was recovered and reused several times without evident loss in activity. Copyright © 2011 John Wiley & Sons, Ltd.