A highly diastereoselective, catalytic three-component assembly reaction for the synthesis of spiropyrrolidinyloxindoles

Evaluation of diethyl 4-(5-bromo-1H-indol-3-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate: synthesis, anti-corrosion potential, and biomedical applications

The pursuit of advanced multifunctional compounds has gained significant momentum in recent scientific endeavours. This study is dedicated to elucidating the synthesis, rigorous characterization, and multifaceted applications-encompassing anti-corrosion, antimicrobial, and antioxidant properties-of Diethyl 4-(5-bromo-1H-indol-3-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate. The 1,4-dihydropyridine derivative was meticulously synthesized through a strategic reaction of ethyl acetoacetate, ammonium acetate, and 5-bromoindole-3-carboxaldehydein the ethanol medium at 60  C. Subsequent spectral validations were conducted using sophisticated techniques, namely FTIR, NMR, and Mass spectrometry, resulting in data that perfectly resonated with the hypothesized chemical structure of the compound. Its anti-corrosive potential was assessed on mild steel subjected to an aggressive acidic environment, employing comprehensive methodologies like gravimetric analysis, Tafel polarization, and EIS. Concurrently, its antimicrobial prowess was ascertained against a spectrum of bacterial and fungal pathogens viz., Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas, Candida albicansandAspergillusniger, leveraging the disc diffusion method and using Gentamicin as a reference standard.The empirical results illustrated a substantial decrement in corrosion rates with ascending concentrations of the organic compound, achieving an apex of anti-corrosive efficacy at 81.89% for a concentration of 2 × 103 M. Furthermore, the compound outperformed Gentamicin in antimicrobial screenings, manifesting superior efficacy against all tested pathogens. The antioxidant potential, quantified using the DPPH free radical scavenging assay against ascorbic acid as a benchmark, was found to have an IC50 value of 113.964 ± 0.076 µg/ml.This comprehensive investigation accentuates the paramount potential of the synthesized dihydropyridine derivative in diverse domains-from industrial applications as a corrosion inhibitor to therapeutic avenues given its pronounced antimicrobial and antioxidant capabilities. The compelling results obtained pave the way for expansive research and development initiatives cantered around this multifaceted compound.

Direct synthesis of pentasubstituted pyrroles and hexasubstituted pyrrolines from propargyl sulfonylamides and allenamides

Multisubstituted pyrroles are important fragments that appear in many bioactive small molecule scaffolds. Efficient synthesis of multisubstituted pyrroles with different substituents from easily accessible starting materials is challenging. Herein, we describe a metal-free method for the preparation of pentasubstituted pyrroles and hexasubstituted pyrrolines with different substituents and a free amino group by a base-promoted cascade addition-cyclization of propargylamides or allenamides with trimethylsilyl cyanide. This method would complement previous methods and support expansion of the toolbox for the synthesis of valuable, but previously inaccessible, highly substituted pyrroles and pyrrolines. Mechanistic studies to elucidate the reaction pathway have been conducted.

Copper-catalyzed condensation of imines and α-diazo-β-dicarbonyl compounds: modular and regiocontrolled synthesis of multisubstituted pyrroles

The Cu-catalyzed condensation of ketimines and diazodicarbonyl compounds enables the rapid and regiocontrolled synthesis of pharmaceutically relevant multisubstituted pyrroles.

In the presence of a copper(ii) catalyst, enolizable imines bearing various N-substituents and α-diazo-β-ketoesters undergo denitrogenative and dehydrative condensation to afford highly substituted pyrroles in moderate to good yields with exclusive regioselectivity. The reaction likely involves nucleophilic addition of the imine nitrogen to a copper carbenoid, tautomerization of the resulting azomethine ylide to an α-enaminoketone, and a subsequent enamine–ketone cyclocondensation. With Yb(OTf)₃ as a unique cocatalyst, α-diazo-β-diketones also participate in the same condensation reaction. The present reaction is applicable to acyclic, exocyclic, and endocyclic imines with tolerance of a broad range of functional groups and heterocyclic moieties, thus opening a new convenient route for the synthesis of the lamellarin family of natural products.

Cu(II)-promoted transformations of α-thienylcarbinols into spirothienooxindoles: regioselective halogenation of dienyl sulfethers containing electron-rich aryl rings

Under the promotion of Cu(II) salts, the α-thienylcarbinols with an N-phenyl carbonyl group at the other α-position are converted into three different ranges of spirothienooxindoles involving dearomatizing Friedel-Crafts reaction. In addition, the unprecedented regioselective CuX(2)-mediated C-H functionalization/halogenation of dienyl sulfether containing electron-rich aryl rings is presented.

An N-heterocyclic carbene/Lewis acid strategy for the stereoselective synthesis of spirooxindole lactones

A cooperative catalysis approach for the enantioselective formal [3+2] addition of α,β-unsaturated aldehydes to isatins has been developed. Homoenolate annulations of β-aryl enals catalyzed by an N-heterocyclic carbene (NHC) require the addition of lithium chloride for high levels of enantioselectivity. This NHC-catalyzed annulation has been used for the total synthesis of maremycin B.

Highly stereoselective Brønsted acid catalyzed synthesis of spirooxindole pyrans

A Brønsted acid-catalyzed Prins-type cyclization sequence to construct spirooxindole pyrans in high yields and excellent diastereoselectivity has been developed. The combination of a β-hydroxy dioxinone fragment and isatin dimethyl acetal generate oxa-spirooxindoles efficiently. These compounds are diversifiable scaffolds that tap into the rich chemistry of dioxinones.

Acylideneoxoindoles: a new class of reversible inhibitors of human transglutaminase 2

Inhibitors of human transglutaminase 2 (TG2) are anticipated to be useful in the therapy of a variety of diseases including celiac sprue as well as certain CNS disorders and cancers. A class of 3-acylidene-2-oxoindoles was identified as potent reversible inhibitors of human TG2. Structure-activity relationship analysis of a lead compound led to the generation of several potent, competitive inhibitors. Analogs with significant non-competitive character were also identified, suggesting that the compounds bind at one or more allosteric regulatory sites on this multidomain enzyme. The most active compounds had K(i) values below 1.0 μM in two different kinetic assays for human TG2, and may therefore be suitable for investigations into the role of TG2 in physiology and disease in animals.

Synthesis of some new mono- and bis-polycyclic aromatic spiro and bis-nonspiro-beta-lactams

Some new mono-and bis-polycyclic aromatic spiro-beta-lactams and bis-non spiro-polycyclic aromatic beta-lactams have been synthesized from imines derived from anthracene-9-carbaldehyde, 2-naphtaldehyde and a ketene derived from 9H-xanthene-9-carboxylic acid and phenoxyacetic acid by a [2+2] cycloaddition reaction. The cycloadducts were characterized by spectral data, including 1H-NMR, 13C-NMR, IR and elemental analyses. The configurations of some of these mono-spiro-beta-lactams were established by X-ray crystal analysis.

Pyrrolidinyl-spirooxindole natural products as inspirations for the development of potential therapeutic agents

The 3,3'-pyrrolidinyl-spirooxindole unit is a privileged heterocyclic motif that forms the core of a large family of alkaloid natural products with strong bioactivity profiles and interesting structural properties. Significant recent advances in the synthesis of this fused heterocyclic system have led to intense interest in the development of related compounds as potential medicinal agents or biological probes.

Microwave-assisted Piloty-Robinson synthesis of 3,4-disubstituted pyrroles

The synthesis of N-acyl 3,4-disubstituted pyrroles can be accomplished directly from hydrazine and an aldehyde via a Piloty-Robinson pyrrole synthesis. The use of microwave radiation for the cyclization and pyrrole formation greatly reduces the time necessary for this process and facilitates moderate to good yields from hydrazine for the corresponding 3,4-disubstituted products (5-12). By simple hydrolysis, the free N-H pyrroles can be accessed after the Piloty-Robinson reaction and then used directly in the synthesis of octaethylporphyrin (H2OEP, 14) and octaethyltetraphenylporphyrin (H2OETPP, 15).