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For the first time, an elegant, metal-free and concise route using a pseudo five-component reaction of dimethyl acetylenedicarboxylate, mono/bis- aromatic aldehydes and amines with trifluoroacetic acid as an effective organocatalyst to afford novel and diverse substituted bis-2,5-dihydrofuran-3-carboxylates in good yields at ambient temperature has been described. The prominent features of this protocol are the energy sustainability, wide range of functional group tolerance, shorter reaction time, no column chromatographic purification, facile experimental and work-up procedure. The present one-step, cascade synthetic approach is straightforward that could avoid hazardous reagents/solvents and is turned to be a benign chemistry for the preparation of potent bis-O-heterocyclics on a multigram scale.

A novel, efficient and one-pot multicomponent copper-catalyzed amination of N-pyridyl imines is described. This, one-pot, multicomponent reaction, in which imine acts as a directing group by chelating to the metal core, affords a domino approach for the transformation of the commercial pyridinamines, aldehydes and azide into valuable imidazo[4, 5-b]pyridines with wide substrate extent and diversity.

Simple but effective and eco-friendly metal-free alkyl(aryl) transfer-aromatization-alkylation domino (ATAAD) approach was demonstrated to synthesize branched hydroquinones in good to excellent yields. This high atom economy approach proceeded through molecular iodine-catalyzed aromatization of p-quinols followed by C–C bond formation with diaryl carbinols. The use of inexpensive catalyst and easily accessible starting materials rendered this clean method more exciting for wide substrate scope to afford symmetrical and unsymmetrical branched hydroquinones. Short reaction time, easy workup and gram-scale preparation are the significant features of this hitherto unknown synthesis of the title compounds.

A domino Sonogashira coupling and hydroamination reaction between o-iodo-N,N-dimethylaniline derivatives and propargyl sulfonamides are described. This protocol allows access to a variety of indole-2-methylsulfonamides in good to excellent yields. The structures of the synthesized compounds are confirmed by XRD studies.

An efficient and operational simple synthetic method has been developed towards the preparation of important biologically active N-heterocyclic scaffolds. The present method associated with the use of inexpensive and easy to prepare nitroaromatics as substrates. The key step of the developed protocol rely on the reductive cyclization of nitro-compounds in presence of Mo(VI) as catalyst and phosphine as deoxygenative agent. It has been shown that depending on the nature of substrates two distinct heterocyclic scaffolds such as 1-hydroxyphenazines and quinoxalines can be synthesized in high yields. It is envisaged that both 1-hydroxyphenazines and quinoxalines exhibits potential pharmacological profiles and offers novel landscapes in medicinal chemistry, and drug discovery research. Considering the limited number of methods available in literature for the preparation of 1-hydroxyphenazines, the present method serves an efficient and economical alternative towards this scaffold.

In this article we present the unprecedented preparation of 4,7-dihydro-1H-pyrazolo[3,4-b]pyridine-5-nitriles and pyrazolo[3,4-b]pyridine-5-nitrile derivatives by the reaction of mono-substituted aryl/heteroarylhydrazines with 3-aryl-3-oxopropanonitriles in ethanol in the presence of HNO3 (conc.). This multi-component reaction requires the in situ oxidation of the ethanol (used as a solvent) to acetaldehyde, resulting in a domino assemblage of the starting materials. The resulting products were unambiguously and rigorously characterised based on IR, NMR (1D and 2D techniques), MS and X-ray crystallography studies. Based on the results obtained from a series of reactions we also propose a mechanism for this unexpected synthesis which confirmed the involvement of in situ oxidation of ethanol and intermediacy of a 5-aminopyrazole species.

A mild, general and operationally simple method for the synthesis of 3,4,5-trisubstituted pyrazoles via a domino Horner-Wadsworth-Emmons olefination/1,3-dipolar cycloaddition/oxidation cascade has been developed. This three-component strategy employs commercially available aldehydes, β-ketophosphonates and the Bestmann-Ohira reagent, and delivers a variety of phosphonylpyrazoles in good to excellent yields. In addition, the advantage of using the domino procedure over stepwise process has been demonstrated.

A One pot four-component domino reactions were developed for the synthesis of 5-methyl-4-(2-(3-methyl-4-nitroisoxazol-5-yl)-1-arylethyl)-1H-pyrazol-3-ols derivatives in excellent yield from hydrazine hydrate (1), ethyl acetoacetate (2), aldehyde (3) and 3,5-dimethyl-4-nitro-isoxazole (4) using 10 mol% of piperidine. This method is simple, efficient and multiple bonds were generated (two C−C, one C−N, one O−H and one C=N) in a single step. These novel 5-methyl-4-(2-(3-methyl-4-nitroisoxazol-5-yl)-1-arylethyl)-1H-pyrazol-3-ol derivatives are evaluated as anti-bacterial agents.