Lewis acid catalyzed spiro annulation of (Z)-3-amino-acrylates with 2-amino arylbenzamides: one-pot synthesis of pyrrole-quinazoline hybrids

The one-pot domino reaction of ethyl (Z)-3-amino-3-phenylacrylates with 2-amino-N-alkyl/arylbenzamides under Lewis acid catalysis was described as an effective way to construct novel spiro [pyrrole-3,2'-quinazoline] carboxylate derivatives. By combining substituted alkyl/aryl amides with spiro annulated 1H-pyrrole-2,3-diones, this method provides a novel way for producing spiro pyrrole derivatives in good to excellent yields. The current procedure has a number of benefits, including quicker reaction times, a broad tolerance range for functional groups, and the ability to synthesize 2,3-dihydroquinazolin-4(1H)-ones that are of biological importance and take part in organic transformations. This is the first use of molecular hybridization involving linking with pyrrole derivatives and dihydroquinazolin-4(1H)-ones.

Site-specific role of bifunctional graphitic carbon nitride catalyst for the sustainable synthesis of 3,3-spirocyclic oxindoles in aqueous media

Functionalized graphitic carbon nitride (Sg-C₃N₄) has been manufactured and used as a reusable catalyst for the one-pot production of various spiro-pyrano chromenes and spiro indole-3,1′-naphthalene tetracyclic systems in aqueous media. An ultrasound-assisted method has been used for the functionalization of g-C₃N₄. The catalytic functionalities and the structural integrity of the catalyst were characterized via different analytical tools. The catalytic site-specific role of Sg-C₃N₄ was confirmed via various control experiments in one-pot reaction sequences. We recognized that Sg-C₃N₄ acts as a bifunctional acid–base catalyst for the first reaction sequence whereas it is an acidic catalyst for the second reaction sequence during the one-pot production of various spiro-pyrano chromenes. In addition, the bifunctional acid–base catalytic role of Sg-C₃N₄ has been confirmed for the first reaction sequence whereas it has a basic catalytic role for the second reaction sequence during the one-pot production of spiro indole-3,1′-naphthalene tetracyclic systems. Diverse C–C, C–O, and C–N bonds, six-membered cycles, stereogenic centers, and spiro frameworks were formed in a single reaction, enhancing the biocidal profile and possibly resulting in the discovery of new medicinal properties. The mild reaction environment, simple workup, easy separation, low cost, heterogeneity, and recyclability of Sg-C₃N₄ are some rewards of this approach.

Functionalized graphitic carbon nitride (Sg-C₃N₄) has been manufactured and used as a reusable catalyst for the one-pot production of various spiro-pyrano chromenes and spiro indole-3,1′-naphthalene tetracyclic systems in aqueous media.

Transition metal-catalyzed synthesis of spirooxindoles

Spirooxindole is a principal bioactive agent and is observed in several natural products including alkaloids. They are broadly studied in the pharmaceutical field and have a significant role in the evolution of drugs such as anti-viral, anti-cancer, anti-microbial etc. In organic chemistry, an indispensable role is presented by transition metal catalysts. An effective synthetic perspective to spirooxindoles is the use of transition metals as the catalyst. This review discusses the synthesis of spirooxindoles catalyzed by transition metals and covers literature up to 2020.

Pd/β-cyclodextrin-catalyzed C–H functionalization in water: a greener approach to regioselective arylation of (NH)-indoles with aryl bromides

A greener and more practical approach to the regioselective C3/C2-arylation of (NH)-indoles with (hetero)aryl bromides in water is developed via the Na2PdCl4-catalyzed and β-cyclodextrin ligand-mediated cross-coupling reactions.

A quantum chemical study of encapsulation and stabilization of gallic acid in β-cyclodextrin as a drug delivery system

This research paper describes the study of the inclusion complex formation of a 1:1 stoichiometry ratio of host–guest inclusion complex (X-β-CD) between gallic acid (GA), which is reported to have anti-cancer effects, and β-cyclodextrin (β-CD). The use of β-CD for the encapsulation of bioactive compounds can protect the drugs against conjugation and metabolic inactivation and improve the aqueous solubility for increasing their capacity to functionalize the products. The objective of this study is to give insight on the mechanism of complexation and the capability of β-CD to encapsulate GA compound (X) in gas and solution phases. We examine and compare the performances of different quantum mechanical methods, namely HF/6-31G* and density functional theory (DFT; B97D3/6-31G* functional including dispersion correction), to study the importance of the contribution of the dispersion forces and the hydrogen bonding in the mechanism of interaction. The stability of the optimized geometries of the complex was evaluated with the supermolecule method. Two modes of complexation are taken into consideration. Moreover, the inclusion complex can be confirmed using the frontier molecular orbital (FMO) theory, the global indices of reactivity, the electronic populations condensed natural bond orbital (NBO) analysis, and the molecular docking, which examine the quality and the nature of the hydrophobic interactions during the complexation process.

Synthesis of spiropyran derivatives over 1-(carboxymethyl) pyridinium iodide as nanostructured pyridinium salt under aqueous media

In this work, acetic acid functionalized pyridinium salt, namely 1-(carboxymethyl)pyridinium iodide {[cmpy]I}, has been applied as reusable nanostructured catalyst for green, simple and efficient preparation of spiropyrans by the one-pot domino Knoevenagel–Michael–cyclization reaction of isatin derivatives or acenaphthenquinone, with malononitrile, and 1,3-dicarbonyl compounds under aqueous media. Moreover, 1H and 13C NMR, mass, CHN analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), differential thermal gravimetric (DTG), X-ray diffraction analysis (XRD), and calculation of crystallite size and interplaner distance of the catalyst have been studied.

Base free synthesis of iron oxide supported on boron nitride for the construction of highly functionalized pyrans and spirooxindoles

BN@Fe₃O₄ network was synthesized via chemical reduction followed by aerial oxidation in absence of base and was subsequently used for the synthesis of highly functionalized pyrans and spirooxindoles derivatives on water.

Rapid and Efficient Synthesis of Spiro-Oxindoles using Fe3+-Montmorillonite under Ultrasonic Irradiation

A simple and efficient one-pot three-component approach was devised for the synthesis of spiro-oxindoles through the reaction of isatin derivatives, malononitrile and 1,3-dicarbonyl compounds in the presence of modified montmorillonite (Fe3+-mont.) under ultrasonic irradiation. The reaction furnished the desired products in excellent yields (85–95%) and short reaction times (2–7 min).

Silica sulfuric acid magnetic nanoparticle: an efficient and ecofriendly catalyst for synthesis of spiro[2-amino-4H-pyran-oxindole]s

Silica sulfuric acid magnetic nanoparticles efficiently catalyze the one-pot, three-component reaction of isatins and malononitrile with dimedone, 1,3-dimethylbarbituric acid or 4-hydroxycoumarin in EtOH–H2O to afford the corresponding spiro[2-amino-4H-pyran-oxindole] derivatives in high yields under ultrasound irradiation at 60 °C. The heterogeneous nanocatalyst could be recovered easily from the reaction mixture using an external magnet and reused many times without significant loss of its catalytic activity.

DABCO-functionalized mesoporous SBA-15: an efficient and recyclable catalyst for the synthesis of spiro-pyranoxindoles as antioxidant agents

A series of spiro-pyranoxindole derivatives were prepared in good yields via a three-component reaction of isatins with activated methylene reagents and kojic acid using 1,4-diazabicyclo[2.2.2]octane (DABCO) immobilized on mesoporous SBA-15 as a heterogenized organocatalyst in aqueous media. The synthesized compounds were evaluated for their antioxidant activity by a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay.