A facile regio- and stereoselective synthesis of novel dispirooxindolyl-[acridine-2′,3-pyrrolidine/thiapyrrolizidine]-1′-ones via 1,3-dipolar cycloaddition of azomethine ylides

An efficient one-pot synthesis and docking studies of bioactive new antiproliferative dispiro[oxindole/acenaphthylenone‒benzofuranone] pyrrolidine scaffolds

A new and efficient method has been developed to synthesize dispiro[oxindole/acenaphthylenone-benzofuranone]pyrrolidine compounds. This is done by triggering the 1,3-dipolar cycloaddition reaction of azomethine ylides by reacting isatin/acenaphthoquinone with L-picolinic acid/L-proline/sarcosine/L-thioproline/tetrahydroisoquinolines, in a highly regioselective manner in an ionic liquid [DBU][Ac] with 4'-chloro-auron[2-(4-chlorobenzylidene)benzofuran-3(2H)-one]. Single-crystal X-ray diffraction data support the proposed structures of the new compounds. The heterocycles derived from amino acids such as L-picolinic acid, L-proline, and L-thioproline showed significant inhibitory effects against six human solid tumors, including lung, breast, cervix, colon, and others. These new structures were also tested in the active sites of the MDM2 receptor to further study their antiproliferative effects.

Azomethine Ylides-Versatile Synthons for Pyrrolidinyl-Heterocyclic Compounds

Azomethine ylides are nitrogen-based three-atom components commonly used in [3+2]-cycloaddition reactions with various unsaturated 2π-electron components. These reactions are highly regio- and stereoselective and have attracted the attention of organic chemists with respect to the construction of diverse heterocycles potentially bearing four new contiguous stereogenic centers. This review article complies the most important [3+2]-cycloaddition reactions of azomethine ylides with various olefinic, unsaturated 2π-electron components (acyclic, alicyclic, heterocyclic, and exocyclic ones) reported over the past two decades.

The catalytic influence of phosphotungstic acid-functionalized Fe3O4 MNPs blended with TiO2 on the synthesis of novel spiro-acridines and the evaluation of their medicinal potential through molecular docking studies

This manuscript describes an effective and rapid three-component synthesis of a novel series of spiro-acridine derivatives by integrating the pharmacologically dynamic hydantoin-phenytoin as the prime synthetic equivalent. The process was accelerated by Fe3O4@TiO2-PTA magnetic nanoparticles (MNPs), which acted as the heterogeneous catalytic system, under ultrasonic conditions. The reaction was performed in the green PEG-200 solvent under aerophilic conditions to obtain products with excellent yields. The characteristics of the synthesized magnetic nano-catalysts were corroborated through powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDAX), FT-IR, and VSM techniques. In addition, the structures of the synthesized compounds were ascertained on the basis of elemental analyses and spectro-analytical data (1H NMR, 13C NMR, and mass spectrometry). High yields, smaller E-factor, considerable atom economy, easy recovery, and recyclability of the catalyst and solvent are the captivating features of the developed protocol. Moreover, in view of the ongoing global research on COVID-19, herein, we tried to identify the potential sites of the synthesized moiety that can suitably fit the receptor sites of the main protease of SARS-CoV-2 (SARS-CoV-2 Mpro).

Crystal structure of 7'-(4-chloro-phen-yl)-2''-(4-meth-oxy-phen-yl)-7',7a',7'',8''-tetra-hydro-1'H,3'H,5''H-di-spiro-[indoline-3,5'-pyrrolo-[1,2-c]thia-zole-6',6''-quinoline]-2,5''-dione and an unknown solvent

The asymmetric unit of the title compound, C34H28ClN3O3S, contains two independent mol-ecules (A and B). They differ essentially in the orientation of the 4-meth-oxy-phenyl ring with respect to the pyridine ring of the quinoline moiety; this dihedral angle is 37.01 (18)° in mol-ecule A but only 7.06 (17)° in mol-ecule B. In both mol-ecules, the cyclo-hexa-none ring of the iso-quinoline unit has a half-chair conformation. In the pyrrolo-thia-zole ring system, the pyrrolo ring in mol-ecule A has a twisted conformation on the N-C fused bond and an envelope conformation in mol-ecule B with the N atom as the flap. The thia-zole rings of both mol-ecules have twisted conformations on the N-C fused bond. In the crystal, the A mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(8) ring motif. These dimers are linked to the B mol-ecules by an N-H⋯N hydrogen bond and a series of C-H⋯O hydrogen bonds, forming layers lying parallel to the (101) plane. The layers are linked by C-H⋯π inter-actions and offset π-π inter-actions [inter-centroid distance = 3.427 (1) Å], forming a supra-molecular framework. The contribution to the scattering from a region of highly disordered solvent mol-ecules was removed with the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The solvent formula mass and unit-cell characteristics were not taken into account during refinement.

Crystal structure and Hirshfeld surface analysis of 4'-(2-chloro-phen-yl)-1'-methyl-3''-phenyl-7'',8''-di-hydro-5''H-di-spiro-[indoline-3,2'-pyrrolidine-3',6''-iso-quinoline]-2,5''-dione

In the title di-spiro compound, C₃₂H₂₆ClN₃O₂, the cyclo-hexa-none ring of the iso-quinoline unit has a distorted envelope conformation, with the methyl-ene C atom adjacent to the spiro C atom as the flap. The central 1-methyl-pyrrolidine ring has an envelope conformation with the N atom as the flap. The mean planes of the indolin-2-one ring system, the chloro-benzene ring and the iso-quinoline ring system are inclined to the mean plane of the central 1-methyl-pyrrolidine ring by 87.95 (11), 71.01 (12) and 88.81 (10)°, respectively. There are two short C-H⋯O intra-molecular contacts present. In the crystal, mol-ecules are linked via C-H⋯ O hydrogen bonds, forming chains along the a-axis direction. The NH H atom is involved in a weak N-H⋯O hydrogen bond with the same carbonyl O atom. There are no further significant inter-molecular contacts present. The largest contribution to the overall Hirshfeld surface of 52.3% is due to H-H contacts.

Potent Synergy between Spirocyclic Pyrrolidinoindolinones and Fluconazole against Candida albicans

A spiroindolinone, (1S,3R,3aR,6aS)-1-benzyl-6'-chloro-5-(4-fluorophenyl)-7'-methylspiro[1,2,3a,6a-tetrahydropyrrolo[3,4-c]pyrrole-3,3'-1H-indole]-2',4,6-trione, was previously reported to enhance the antifungal effect of fluconazole against Candida albicans. A diastereomer of this compound was synthesized, along with various analogues. Many of the compounds were shown to enhance the antifungal effect of fluconazole against C. albicans, some with exquisite potency. One spirocyclic piperazine derivative, which we have named synazo-1, was found to enhance the effect of fluconazole with an EC50 value of 300 pM against a susceptible strain of C. albicans and going as low as 2 nM against some resistant strains. Synazo-1 exhibits true synergy with fluconazole, with an FIC index below 0.5 in the strains tested. Synazo-1 exhibited low toxicity in mammalian cells relative to the concentrations required for antifungal synergy.

A Facile Regioselective 1,3-Dipolar Cycloaddition Reaction for the Synthesis of Dispiro[Indole-3,2-Pyrrolidine-3′,5″-[1,3]Thiazolidine] Derivatives

The 1,3-dipolar cycloaddition reaction of azomethine ylides generated in situ from isatin and sarcosine with 5-arylmethylene-3-phenyl-2-thioxothiazolidin-4-one in refluxing toluene produced the 2″-thioxodispiro[indole-3,2′-pyrrolidine-3′,5″-[1,3]thiazolidine]-2,4″-dione derivatives in good yields (80–88%). The structures were assigned by 1H NMR, IR, elementary analysis and single crystal X-ray diffraction analysis through which the cycloaddition reaction was found to be highly regio- and stereo-selective.

Highly diastereoselective synthesis of imidazolidine-dispirooxindoles via three-component [3 + 2] cycloadditions of isatins, 2-(aminomethyl)pyridine and isatin-based imines

In the presence of Et₃N, the [3 + 2] cycloaddition of isatins, 2-(aminomethyl)pyridine and isatin-based imines proceeded readily, and furnished novel imidazolidine-dispirooxindoles in up to 84% yield with up to >99 : 1 diastereoselectivity.

Synthesis of sulfur containing dihydro-pyrrolo derivatives and their biological evaluation as antioxidants

The 1,3-dipolar cycloaddition to N-phenylmaleimide of azomethine ylides, generated in situ from sulfanyl-substituted imines of glycine esters, yields 5H-dihydro-pyrrolo products with syn diastereoselectivity. The syn (major) and anti (minor) products were isolated chromatographically and fully characterized by spectroscopic methods and in two cases also by X-ray analysis. The diastereomeric cycloadducts were tested for their antioxidant activity with good results.