Organocatalysis in aqueous micellar medium: a new protocol for the synthesis of [1,2,4]-triazolyl-thiazolidinones

A new environmentally friendly methodology for the efficient synthesis of biologically significant triazole thiazolidinone hybrids in aqueous medium, using acetic acid as an organocatalyst in the presence of cetyltrimethylammonium bromide (CTAB) surfactant has been developed for the first time. The effect of several surfactants on the yield and completion time of the reaction was investigated and it was found that the use of CTAB at 60 °C gave the best results (79–96% in 20 min–35 min) for the synthesis of the target compounds.     

Sodium stearate-catalyzed multicomponent reactions for efficient synthesis of spirooxindoles in aqueous micellar media

A new type of Lewis base-surfactant-combined catalyst (LBSC), sodium stearate, was applied as a catalyst in three-component one-pot reaction involving isatin, malononitrile, and 1,3-dicarbonyl compounds to afford the corresponding spirooxindoles derivatives in good yields (91-97%) under aqueous micellar media.     

The methods of determination of critical micellar concentrations of the amphiphilic systems in aqueous medium

Science is the attempt to make the chaotic diversity of our sense-experience to a logically unified system of thought. A sound theoretical basis and a rational physicochemical understanding based on experimental findings lead to a proper understanding of a topic. Colloid chemistry strengthened its footing by the extensive studies on gold sols by Michael Faraday in 1850s, however, the term “colloid” was coined by Thomas Graham in 1861. Historically, the Stone Age paintings in the Lascaux cave in France and the written records of Egyptian pharaohs were produced with stabilized colloid pigments. The part of colloid science dealing with amphiphilic molecules is so diverse on its own that it is dealt in a separate branch called the “association colloid”. A key development in the study of association colloids was the observation by James McBain that the osmotic pressure of salts of alkali metal fatty acid displayed a pronounced break in the concentration beyond a specific characteristic concentration, after which the osmotic coefficient remained almost constant (Evans and Wennerstrom, 1994). McBain attributed this fact to the self-association of these molecules among themselves (McBain, 1913, McBain, 1944) in solution. Here, we are providing a molecular as well as thermodynamic approach toward the micellization process.     

Boric acid in aqueous micellar medium: an effective and recyclable catalytic system for the synthesis of aryl-7,8-dihydro[1,2,4]triazolo[4,3-a]pyrimidine-6-carbonitriles

A simple, green, and efficient protocol is reported for the preparation of aryl-7,8-dihydro[1,2,4]triazolo[4,3-a]-pyrimidine-6-carbonitriles through one-pot multi component reaction using substituted aromatic aldehydes, malononitrile, and 3-amino[1,2,4]triazole. The reaction is catalyzed by boric acid in aqueous micellar condition. Present protocol incorporates environmentally non-hazardous reaction condition, easy work-up, and use of recyclable catalytic system with associated benefits like excellent yield (84–96%) and shorter reaction time (20 min). Proposed methodology offers rapid access to substituted aryl-7,8-dihydro[1,2,4]triazolo[4,3-a]pyrimidine-6-carbonitriles with high atom-economy and catalytic efficiency.     

An efficient and green method for the synthesis of [1,3]oxazine derivatives catalyzed by thiamine hydrochloride (VB1) in water

An efficient and convenient synthesis of 1,3-oxazine derivatives has been achieved by the one-pot, multicomponent condensation of α- or β-naphthol, an aniline and formaldehyde using thiamine hydrochloride (VB₁) as a versatile biodegradable and reusable catalyst in water as a universal solvent.     

Sodium chloride: a proficient additive for the synthesis of pyridine derivatives in aqueous medium

A facile and convenient synthesis of substituted pyridine derivatives catalysed by NaCl in the presence aqueous media under reflux and ultrasound irradiation has been developed via a one-pot multicomponent reaction, in which four new bonds were formed. Particularly valuable features of this protocol including mild conditions, simple execution, broad substrate scope and good yields of products make it an efficient and promising synthetic strategy to build pyridine skeleton.     

A new green approach for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-one derivatives using task specific acidic ionic liquid[NMP]H_2PO_4

12-Aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-one derivatives were synthesized by a convenient and environmentally benign procedure involving multicomponent condensation reactions of substituted aromatic aldehydes with 2,7-dihydroxynaphthalene/2-naphthols/2,6-dihydroxynaphthlene and cyclic 1,3-dicarbonyl compounds in task specific acidic ionic liquid[NMP]H_2PO_4 at 80 ℃.This protocol has proved to be efficient in terms of good yields,operational simplicity,easy workup,recyclability of reaction medium/catalyst,and short reaction time.     

Choline hydroxide: An efficient and biodegradable catalyst for the synthesis of 2-amino-3-nitro-4H-chromene derivatives in an aqueous medium

Abstract

An expedient, eco-friendly and efficient procedure for the synthesis of novel 2-amino-3-nitro-4H-chromene derivatives has been developed through the reaction of various 2-hydroxybenzaldehydes and (E)-N-methyl-1-(methylthio)-2-nitroethenamine in the presence of the basic ionic liquid catalyst (choline hydroxide (ChOH)) at room temperature an aqueous medium. The advantageous of this method is a biodegradable and recyclable catalyst, mild, environmentally friendly and high products yields (83-96%) in short reaction times.     

Thiamine hydrochloride as a efficient catalyst for the synthesis of amidoalkyl naphthols

A simple, efficient, and practical procedure for the synthesis of amidoalkyl naphthols using thiamine hydrochloride (VB₁) as a novel catalyst is described in high yields. The salient features of the catalyst are efficiency, inexpensiveness, non-toxicity, and metal ion free.     

A simple and clean procedure for three-component synthesis of spirooxindoles in aqueous medium

A simple and efficient one-pot three-component synthesis of the biologically important spirooxindoles scaffold was carried out by the reaction of isatin, activated methylene reagent, and 1,3-dicarbonyl compounds in aqueous medium. This method is of great value because of its environmentally benign character, high yield processing, and easy handling.     

A new domino Knoevenagel-hetero-Diels-Alder reaction: an efficient catalyst-free synthesis of novel thiochromone-annulated thiopyranocoumarin derivatives in aqueous medium

An efficient catalyst-free synthesis of novel pentacyclic thiochromone-annulated thiopyranocoumarin derivatives is achieved via domino Knoevenagel-hetero-Diels-Alder reaction of 4-hydroxy dithiocoumarin and O-acrylated salicylaldehyde derivatives in H₂O as solvent. The products are formed in good yields with high regio- and stereo-selectivity.     

Green chemical synthesis of fluorinated 1,3,5-triaryl-s-triazines in aqueous medium under microwaves as potential antifungal agents

Reasonable pure fluorinated s-triazines were synthesized in quantitative yield (96-99%) in 2-3 min in aqueous medium under microwaves, by reaction of fluorinated anilines and aqueous formaldehyde. All synthesized compounds have been screened in vitro for their antifungal activity against Rhizoctonia solani, Fusarium oxysporum, and Collectotrichum capsici.     

Electro organic synthesis as green and sustainable approach for synthesis of chloro substituted benzyl alcohols

The rising interest in advances of sustainable and greener synthetic approaches has encouraged chemists to investigate novel methods to stimulate organic compounds. The benzyl alcohol and its derivatives are industrially significant chemicals owing to their huge applications in petrochemical industries. In this context a green and sustainable approach for synthesis of Chloro substituted benzyl alcohols has been established. In present research paper cyclic voltammetry study followed by constant current electrolysis and characterization of synthesized 2-Chlorobenzyl alcohol, 3-Chlorobenzyl alcohol, 4-Chlorobenzyl alcohol and 2,4-Dichlorobenzyl alcohol has been reported. Cyclic voltammetry measurements have been employed to setup optimum conditions for electrolysis and to find out electrochemical nature of various Chloro substituted benzaldehydes. Then these results have been judiciary used to carry out electrochemical reduction of various Chloro substituted benzaldehydes using constant current electrolysis. Influence of scan rate and pH on reduction peaks has also been investigated referring irreversible electron transfer phenomenon in basic medium. The kinetic parameters for reduction reactions have been estimated showing the process under the influence of diffusion control. The characterization of electrochemically synthesized 2-Chlorobenzyl alcohol, 3-Chlorobenzyl alcohol, 4-Chlorobenzyl alcohol and 2,4-Dichlorobenzyl alcohol has been done by using spectroscopic techniques such as IR, ¹HNMR and Mass spectral analysis. This has a scientific achievement in terms of the obtained products (2-Chlorobenzyl alcohol, 3-Chlorobenzyl alcohol, 4-Chlorobenzyl alcohol and 2,4-Dichlorobenzyl alcohol) and their derivatives which are industrially and pharmaceutically significant chemicals owing to their huge applications in petrochemical industries and medical sectors. Throat lozenges containing dichlorobenzyl alcohol (DCBA) are used for treatment of respiratory tract infections.     

A simple and clean procedure for the synthesis of polyhydroacridine and quinoline derivatives: reaction of Schiff base with 1,3-dicarbonyl compounds in aqueous medium

A clean and simple synthesis of benzo[c]acridine, benzo[a]acridine, pyrido[2,3-c]acridine and benzo[f]quinoline derivatives was accomplished in good to excellent yields via the reaction of Schiff base with 1,3-dicarbonyl compounds in aqueous medium catalyzed by TEBA. The structures were characterized by ¹H NMR, IR and elemental analysis, and confirmed by X-ray diffraction study.     

An efficient ultrasound-promoted method for the synthesis of bis(indole) derivatives

In this paper, the reaction of indole with electron-deficient alkenes in aqueous media is reported. This procedure allows the synthesis of bis(indole) derivatives in good to high yields at 90 °C under silent and ultrasound irradiation conditions. Short reaction times and high yields of desired products are the main advantages of the presented procedure. This reaction catalyzed by 12-tungstophosphoric acid is operationally simple and considers environmental aspects by avoiding toxic catalysts and solvents.     

l-Proline catalyzed expeditious multicomponent protocol for the synthesis of fused N-substituted-2-pyridone derivatives in aqueous medium

N-substituted-2-pyridone derivatives have many pharmaceutical properties. In our research, we have developed an efficient, green, and multicomponent protocol to synthesize such new fused N-substituted-2-pyridone derivatives. Optimum reaction condition was obtained by employing l-proline as an organocatalyst in aqueous SDS solution at 100 °C. Various 1,3-diketones, including indane 1,3-dione with a range of aromatic and aliphatic amines were utilized to synthesize fused 2-pyridone derivatives. The isolation of a reaction intermediate confirmed our proposed mechanism. Water as a reaction medium improved the scope of the reaction methodology to a large extent.     

An efficient method for synthesis of phenacyl derivatives under homogeneous phase transfer catalyst condition in aqueous media

In this letter,a mild and efficient procedure for synthesis of phenacyl derivatives under homogenous catalysis in the presence of tetrabutylammonium bromide in aqueous media is described.The nucleophilic substitution reactions were performed under ecofriendly conditions and gave the corresponding products in high yields and short reaction times.     

Poly(4-vinylpyridinium)hydrogen sulfate: An efficient heterogeneous catalyst for the one-pot synthesis of polyhydroquinolines via unsymmetrical Hantzsch reaction in aqueous medium

A facile and highly efficient protocol for the synthesis of polyhydroquinolines via Hantzsch multicomponent condensation of dimedone, aryl/heteryl aldehydes, ethylacetoacetate and ammonium acetate utilizing poly(4-vinylpyridinium)hydrogen sulfate as a catalyst in aqueous medium has been described. The method offers several advantages such as high yield, short reaction time, simple workup, easy separation of the catalyst and its reusability.     

An eco-compatible multicomponent strategy for the synthesis of new 2-amino-6-(1H-indol-3-yl)-4-arylpyridine-3,5-dicarbonitriles in aqueous micellar medium promoted by thiamine-hydrochloride

A thiamine hydrochloride (VB₁) accelerated, one-pot synthesis of 2-amino-6-(1H-indol-3-yl)-4-arylpyridine-3,5-dicarbonitriles was achieved via four-component reaction of 3-cyanoacetyl indole, aromatic aldehydes, ammonium acetate, and malononitrile in aqueous micellar conditions by a Knoevenagel condensation reaction followed by Michael-addition, which upon cyclization and dehydration yielded the corresponding product in excellent proportion.     

Greener and rapid access to bio-active heterocycles: room temperature synthesis of pyrazoles and diazepines in aqueous medium

An expeditious room temperature synthesis of pyrazoles and diazepines by condensation of hydrazines/hydrazides and diamines with various 1,3-diketones is described. This greener protocol was catalyzed by polystyrene supported sulfonic acid (PSSA) and proceeded efficiently in water in the absence of any organic solvent within 1-2 min.