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We have developed an efficient, novel one-pot multicomponent protocol for the synthesis of hexahydro-4H-indazol-4-onederivatives using β-cyclodextrin as a biomimetic catalyst in an aqueous medium. To the best of our knowledge, the targeted molecules have not been reported in the literature till now. The present method is very effective for our densely functionalized and diversified targeted molecules and includes several advantages like environment benign, cost-effectiveness, short reaction times, high yields and recyclability of the catalyst.

A simple and novel methodology for the synthesis of vinyl thiocyanates from decarboxylative cross-coupling reaction of cinnamic acids with KSCN under the synergistic interactions of visible light irradiation, Cs2CO3, Rose Bengal as the photocatalyst and air as the terminal oxidant at room temperature is reported. The reaction takes place by a radical pathway as evidenced from our experiments and literature. The report is the first example on the visible-light mediated thiocyanation of cinnamic acids, which employs environmentally benign and inexpensive starting materials and is characterized by easily removable by-product CO2.

Aim and Objective: An efficient and facile DBU catalysed synthesis of highly significant motif 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidines under solvent-free condition has been reported. Materials and Methods: To a round bottom flask, 1.0 mmol of chalcone (1), 1.5 mmol of 3-amino-1,2,4- triazole (2) and 30 mol% of DBU were added at 70 °C and stirred in solvent-free condition. After the completion of the reaction (monitored by TLC), water (10 ml) was added. The aqueous layer was extracted with ethyl acetate (3 ×10 ml). The combined organic layers were dried over anhydrous Na2SO4. The combined organic layers were evaporated under reduced pressure and the resulting crude product was purified by column chromatography by using ethyl acetate and hexane as eluent. Results: Reaction using chalcone and 3-amino-1,2,4-triazole as model substrates were carried out under different reaction conditions and it was observed that 30 mol% of DBU under the solvent-free condition at 70 °C was the optimum temperature for the proposed synthesis. Conclusion: Use of DBU (an organocatalyst) as a base, operational simplicity, high yield of products and short reaction time are some of the significant advantages associated with the proposed strategy.

Herein, we have described an efficient, eco-friendly, metal free, visible light catalysed synthesis of coumarin based pyrazoles under an open atmosphere involving a photoredox catalyst, which is an inexpensive organic dye. The present strategy is the first example of visible light promoted, aerobic, oxidative cyclization of pyrazoles bearing a coumarin unit via the formation of C–C, C–O and C–N bonds to afford excellent yields of the products in a simple one-pot operation under mild reaction conditions. The major advantages of the present methodology include short reaction time, cost effectiveness, easy work-up, broad substrate scope and high atom economy.

A pragmatic and swift method for the synthesis of Benzo[a]pyrano[2,3-c]phenazine derivatives via one pot, multicomponent strategy by employing β-cyclodextrin in EtOH:H2O (1:1) solvent at 70 °C has been documented here. Utilization of supramolecular catalyst β-cyclodextrin which is highly efficient, green, biodegradable and reusable catalyst augments the synthesis amazingly, is the key feature of the current pathway. The catalyst could be recovered for four successive cycles without significant loss in catalytic activity.

Background:In recent years, photoredox catalysis using eosin Y has gained considerable significance in organic chemistry. It is evolving as a powerful approach in modern organic synthesis for the activation of small molecules.Objective:The use of organic dyes to convert visible light into chemical energy by involving a single-electron transfer with organic substrates has innumerable applications.Method and Results:The present strategy is the first example of visible light promoted, aerobic, oxidative cyclization of chromeno[4,3-b]chromenes and hexahydro-1H-xanthenes via the formation of C–O and C–C bonds to afford excellent yield of the products in a simple one-pot operation under mild reaction conditions.Conclusion:The major advantages of the present methodology include short reaction time, cost effectiveness, easy work-up, broad substrate scope and high atom economy.

Effective methodology that activates selectively either end of a carbon–carbon triple bond requires key challenge of differentiating between the multitude of C C bonds present in complex organic molecule. The synthetic strategy exploited the electronic biases within the substrate and successfully achieved site–selective [bmIm]OH catalyzed C C bond functionalization under mild reaction conditions. This resulted in C-2-selective addition of phenacyl bromide on p-substituted phenyl acetylene and C-1 selective addition on the o-substituted phenyl acetylene leading to C C bond formation. The reaction proceeded smoothly with excellent yield under ambient conditions. This report demonstrates the progress on the catalytic activity of recyclable [bmIm]OH for selective C C bond formation.

The development of a versatile, new biomimetic glucose–water organocatalytic system promoted, one-pot green and practical method for the synthesis of diversified spirochromenes/spiropyrans is reported. To the best of our knowledge this is the first report on the use of a glucose–water system as a catalyst in organic synthesis. Superior green credentials, operational simplicity, easy scale up and recyclability of the catalyst are the key strengths of this method, which combined with attributes like broad substrate scope, mild reaction conditions, short reaction times, cost effectiveness, high atom economy and good to excellent yields make the present method a distinct improvement over existing methods.

An efficient recyclable [bmIm]OH catalyzed and aqua mediated eco-compatible synthesis of biologically versatile 2,8 dioxacyclopenta [a] inden-3-one derivatives. Combination of ionic liquid and water has emerged out as a powerful synthetic tool for constructing C–C, C–S and C–O bonds. Disclosed methodology for introducing broad range of 2-iodophenols, 2-iodothiophenols and tetronic acid in basic ionic liquid with predictable high yield will catch the attention of synthetic chemists. This protocol has documented the notable advances and the applications of ionic liquid in heterocyclic synthesis. The chosen strategy illustrates important issues regarding scope, reactivity, product yield, reaction time, reuse and recyclability that will help in designing new synthetic routes for other heterocyclic synthesis.

A visible light initiated, mild, one pot, multicomponent copper catalyzed azide alkyne [3 + 2] cycloaddition in the presence of organo photoredox catalyst Eosin Y using EtOH:H2O as reaction medium for the synthesis of substituted 1,2,3-triazoles is reported. A facile regioselective ring opening of epoxides followed by 1, 3 dipolar cycloaddition with alkynes under CFL (Compact fluorescent light) irradiation as a source of visible light resulting in the formation of C–N bonds, is the characteristic feature of the present strategy. Scope of the present protocol is further extended by using benzyl chloride in place of epoxide.

The reported work allows an accessible construction of 4-substituted 2-amino-4H-chromenes starting from ethylacetoacetate (1), hydrazine hydrate (2), salicylaldehyde (3) and malononitrile (4) in the presence of visible light. The salient features of the proposed route is being a solvent-free and catalyst-free, one-pot, multi-component reaction with high to excellent yield. Visible light mediation makes the reaction mechanistically interesting and adds to the green credentials of the reaction.

A completely regioselective, environmentally benign strategy for the facile synthesis of biologically important imidazole-fused nitrogen-bridgehead heterocycles has been developed using glycerol/water 4:1 as a green promoting media. The methodology involves the simple coupling of 2-halocarbonyl compounds with 2-aminopyridines, 2-aminopyrimidines, 2-aminopyrazines to obtain a variety of 2-aryl substituted imidazo-pyridines, imidazo-pyrimidines and imidazo-pyrazines containing bridgehead nitrogen. This protocol eliminates the use of toxic catalysts and volatile organic solvents - two key principles in the development of a green chemical process. Other significant highlights include mild reaction conditions, operational simplicity, short reaction times, easy workup and purification process, high yields and potential for scale-up.

A concise and convenient meglumine catalysed, multicomponent, one pot synthetic pathway for pyrroloacridine via 1,3 diketones, aniline and isatin in ethanol:water mixed solvent system has been proposed. Use of an enviromentally benign catalyst, meglumine, an amino sugar was preferred due to remarkable properties such as being inexpensive, recyclable, physiologically inactive and biodegradable. Green reaction condition, broad substrate scope, operational simplicity, incorporation of an eco-efficient catalyst, formation of C−N bond and high yields of product are some important hallmarks of the proposed strategy.

An environment-friendly efficient one-pot, multicomponent condensation of different aldehydes and amines with dialkyl acetylenedicarboxylates, for the synthesis of polysubstituted pyrrol-2-ones and furan-2-ones is disclosed. Key features of this methodology is the use of Potash Alum (K [Al(SO4)2].12H2O) as an eco-friendly, economical and reusable solid catalyst. Use of inexpensive reagents, mild reaction conditions, operational simplicity, short reaction times, no need for chromatographic purification and high yields are the other key features of the disclosed strategy.

The discovery of a new, malic acid promoted, eco-friendly Friedlander approach to varied multisubstituted quinolines is disclosed. To the best of our knowledge, this is the first report on the use of malic acid, classified as one of the 12 biobased hot molecules by the US Department of Energy, as an organopromoter in organic synthesis and includes many benefits like wide substrate scope, solvent free ambient reaction conditions, short reaction times, operational simplicity, cost effectiveness, high atom economy, good to excellent yields, and recylability of the organopromoter, making it a valuable green alternative to the existing methods. The versatility and practicability of the developed method was further established by its successful application towards the targeted synthesis of some important quinoline molecules and successful scale up.

A mild, eco-efficient and metal-free synthetic protocol for the production of biologically significant scaffold dihydropyrano[2,3-c]pyrazoles via reaction between ethylacetoacetate (1), hydrazine hydrate (2), aromatic aldehydes (3) and malononitrile (4) as reactants and exploiting visible light as a reaction promoter has been developed. Cost effectiveness, nontoxicity, being catalyst-free and solvent-free, the easy-availability of reactants and non-involvement of specific glasswares and a photo-reactor system are some of the significant traits of the present protocol. The scope of the current methodology is further extended by using diethyl acetylene dicarboxylate (6) as a reactant in place of ethylacetoacetate.

The development of unique, mild and efficient one pot, multicomponent-tandem synthesis of highly functionalized dihydropyrano[2,3-c]chromenes under photochemical activation is reported. The key feature of the present work is the utilization of visible light which is a ubiquitous, inexpensive and eco-sustainable reagent for catalysing the reaction. The reported methodology is the first example of visible light induced synthesis of dihydropyrano[2,3-c]chromenes and includes several advantages like solvent and catalyst free, environmentally benign reaction conditions, operational simplicity, cost effectiveness, short reaction times, high atom economy, and excellent yields, making it a genuinely green protocol.

The development of a visible light promoted, mild and greener approach for the synthesis of highly functionalized thiazoles and imidazo[2,1-b]thiazoles under photochemical activation in EtOH : H2O green medium is demonstrated. The characteristic feature of the present protocol is the utilization of visible light (an omnipresent, nontoxic, environmentally benign and inexpensive reagent) to form C–S and C–N bonds and circumvent the use of catalysts or photosensitizers. The reported protocol is the first example of visible light promoted synthesis of thiazoles and imidazo[2,1-b]thiazoles with various attractive features like being catalyst free, eco-efficient and possessing cost effectiveness, short reaction time, excellent yields and sustainability to fulfill the parameters of green chemistry.

We have established a mild, metal-free, one pot, visible light-catalyzed procedure for a highly regioselective synthesis of 2-nitro-3-arylimidazo [1,2-a] pyridines via nitroalkene and 2-aminopyridine under an open atmosphere involving a photoredox catalyst, Eosin Y, which is an inexpensive organic dye that has been employed as a photo sensitizer in the conversion. This protocol serves as an example of green chemistry, due to the fact that molecular oxygen and visible light have been utilized effectively for the transformation. The procedure involves intramolecular C–N heterocyclization, followed by aerobic oxidation and C–C bond formation at room temperature. This green protocol has also been successfully extended to the regioselective synthesis of 3-substituted indoles via indole and nitroalkene by a free radical pathway.

A clean and efficient, multicomponent-tandem strategy for the synthesis of pyrido[2,3-d]pyrimidines is reported in glycerol, a biodegradable and reusable promoting medium. The advantages of the present methodology includes a one-pot catalyst free environmentally friendly approach, 100% atom economy, cost effectiveness, broad substrate scope, operational simplicity, short reaction times, easy workup procedure and high yields.

A novel protocol has been reported for synthesis of pyrazoles by visible light irradiation in the presence of eosin Y, an organophotocatalyst under atmospheric oxygen. We have successfully carried out a visible light induced Michael addition followed by intramolecular cyclization reactions for the formation of heterocyclic ring. The present method incorporates advantages such as being eco-friendly, involving metal free condition, reporting excellent yields, using minimum reaction time, making use of an easily available catalyst, and eliminating the use of column chromatography.

An efficient and facile protocol has been documented for the synthesis of 4H-chromene and xanthen-1-one derivatives via a three component one pot reaction of salicyladehyde, malononitrile/dimedone and indole utilizing biomimetic catalyst. Affiliation between biomimetic and organocatalyst exhibits a versatile and high catalytic activity emerging to be a sustainable alternative to other catalysts. The significant features of this protocol are compatibility with various types of indole and active-methylene compound, accomplishment of high yields, cleaner reaction condition and avoidance of the use of costly catalysts. Recyclability of β-cyclodextrin a “biomimetic catalyst” is a significant feature of this protocol.

The development of a versatile new one pot, catalyst free, multicomponent-tandem strategy for assembly of spirooxindole-indazolones and spirooxindole-pyrazolines is described. The reported protocol includes several advantages like environmental friendliness, cost effectiveness, high atom economy, short reaction times and high yields. The reported method is the first green synthesis of spirooxindole-indazolones and spirooxindole-pyrazolines.

A highly efficient, green, eco-friendly, one pot protocol has been demonstrated for the synthesis of 2-imino-2H-chromene-3-carbonitrile (3), 2-aminochromene (4) and chromeno(2,3-b)pyridines (5). The synthesis of the chromene nucleus has been carried out under visible light irradiation in a water–ethanol mixture at room temperature using salicylaldehyde and malononitrile in different proportions. The adopted method shows significant advantages such as mild and clean reaction conditions, eco-friendly procedures, absence of catalysts and a short reaction time. This protocol involves the use of CFL as the visible light source and shows high selectivity in the presence of a mixture of ethanol and water. The reaction proceeds with good to excellent yield.

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.

An efficient triphenylphosphine-catalyzed synthesis of β-acetamido carbonyls via multicomponent reaction of aromatic aldehydes, enolizable ketones or β-keto esters, acid chlorides and acetonitrile at room temperature is described. The process is remarkably simple, environmentally benign, and uses Lewis base for the first time in such type of reaction.

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.

A library of 1,3,5-trisubstituted pyrazoles was synthesized in excellent yields from the reaction of aldehyde, phenylhydrazine and alkynes in the presence of iodine via an eco-friendly, simple process performed in aqueous medium. This single pot transformation generates new CN, C–C, C–N bonds and proceeds by a domino reaction involving the formation of Schiff base, Mannich addition and finally intramolecular cyclisation.

An efficient one pot multi-component sequential reaction of phenyl hydrazine, malanonitrile and a diverse range of aldehydes to afford highly functionalised pyrazoles is reported. The reaction proceeds in water using molecular iodine as a catalyst, with no by-product formation, and involves simple operation requiring no column chromatography. Thus, this protocol fulfils all of the criteria that define green chemistry.

A series of novel dihydropyrrolo[2,1-a]isoquinolines and dihydropyrrolo[1,2-a]quinolines have been synthesized from isoquinolines/quinolines, various substituted phenacyl bromides and substituted dialkylacetylenedicarboxylates via [3+2] cycloaddition reaction. The reaction proceeds in aqueous micellar medium with DBU as a catalyst. The present protocol offers a simple one pot sequential reaction affording products in excellent yields.

A microwave-induced technique has been developed for the synthesis of a series of novel spiro indoline-based heterocycles (7a–g) at atmospheric pressure in an open vessel using an environmentally benign procedure. This rapid method produces pure products in good yields within a few minutes in comparison to the conventional procedure developed for the synthesis of these heterocycles. The synthesized compounds have been screened in vitro for antifungal activity against two fungal strains (i.e., Aspergillus niger and Aspergillus flavus). All compounds have shown significant activity against these pathogens. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]

E-mail: dr.jdsau@gmail.comReceived November 22, 2012, Accepted January 9, 2013Herein is reported a simple and efficient synthesis of isoflavones starting from various substituted phenacylbromides and salicylaldehydes in presence of NHC. The mechanism involved domino catalysis type approachwith consumption and regeneration of catalyst in two catalytic cycles. This method proved to be very lucrativeand gives very good yield. The method described here represents an environmentally benign alternative toclassical approach.Key Words : Umpolung, Heterocycles, Thiamine ( N-Heterocyclic carbene), Domino catalysis, Natural Prod-uctsIntroductionOne of the major issues of modern chemistry is thedevelopment of efficient methodologies for the synthesis ofbioactive compounds including natural products and theiranalogues.

The development of new catalyst-free green and efficient protocol to access 5′-thioxospiro[indoline-3,3′-[1,2,4]triazolidin]-2-ones/spiro[indoline-3,3′-[1,2,4]triazolidine]-2,5′-diones, potential privileged scaffolds for drug discovery, is disclosed. Key feature of this methodology is the dual use of glycerol—a recyclable, bioorganic compound, as a solvent cum promoter. Other highlights include use of inexpensive reagents, mild reaction conditions, operational simplicity, short reaction time, no need for chromatographic purification, and high yields.

The development of a new catalyst free green and efficient protocol to access 5′-thioxospiro[indoline-3,3′-[1,2,4]triazolidin]-2-ones/spiro[indoline-3,3′-[1,2,4]triazolidine]-2,5′-diones, potential privileged scaffolds for drug discovery, is disclosed. Key feature of this methodology is the dual use of glycerol - a recyclable, bioorganic compound, as a solvent cum promoter. Other highlights include use of inexpensive reagents, mild reaction conditions, operational simplicity, short reaction time, no need for chromatographic purification and high yields.

The discovery of a new L-valine promoted facile and versatile green synthesis of diversified 2-amino-3-cyano-4H-pyrans using a one pot multicomponent-tandem reaction of aromatic aldehydes, malononitrile, and diverse electron-rich enolizable carbonyl compounds is described. To the best of our knowledge this is the first report on the use of native L-valine as a catalyst in organic synthesis. Environmental friendly, mild reaction conditions, use of easily available inexpensive starting materials, short reaction time, excellent yields, high atom economy, and recyclability of organocatalyst are the major advantages of the disclosed protocol.

Novel spiro-oxindole derivatives were synthesised by one-pot multicomponent reaction using isatins, urea and 1,3-dicarbonyls. β-Cyclodextrin, an oligosaccharide, catalysed the reaction and can be reused for further reaction after recovery. This developed synthetic route is environmentally benign in which water is used as solvent to produce excellent yields of products. The synthesised compounds were evaluated for their antimicrobial activities against two bacteria and two fungi. All the synthesised spiro-oxindoles exhibit significant antimicrobial activity.