Stereoselective synthesis of spirocyclic pyrrolidines/pyrrolizidines/pyrrolothiazolidines using l-proline functionalized manganese ferrite nanorods as a novel heterogeneous catalyst

Synthesis of Spirocyclic Pyrrolidine Compounds via Silver-Catalyzed Asymmetric [3 + 2] Cycloaddition Reaction of Imino Esters with α-Alkylidene Succinimides

In this study, the AgOAc/ThioClickFerrophos (TCF) complex was used to successfully catalyze asymmetric [3 + 2] cycloaddition between glycine imino esters and CO2Me-appended α-alkylidene succinimides to afford spiropyrrolidines in good yields with high diastereo- and enantioselectivities (up to 95% ee). The silver/TCF afforded endo-(2,5-cis) cycloadducts in contrast to the previous exo'-(2,5-trans) selective reaction with ylidene-2,3-dioxopyrrolidine. A wide variety of imino esters bearing electron-donating and electron-withdrawing groups on the phenyl groups and heteroaryl substrates were utilized in this reaction. The scope of α-alkylidene succinimides was investigated, which revealed that substituents on α-benzylidene derivatives had negligible effect on the product yield and stereoselectivity, and α-alkylidene derivatives could be efficiently used as dipolarophiles.

Green synthesis, anti-proliferative evaluation, docking, and MD simulations studies of novel 2-piperazinyl quinoxaline derivatives using hercynite sulfaguanidine-SA as a highly efficient and reusable nanocatalyst

In this study, the immobilization of sulfaguanidine-SA on the surface of FeAl2O4 (hercynite) MNPs (magnetic nanoparticles) as a novel acid nanocatalyst has been successfully reported for the synthesis of 2-(piperazin-1-yl) quinoxaline derivatives via a one-pot multiple-component reaction under green conditions. The products were characterized by SEM, TEM, TGA, EDS, BET technique, VSM, and FTIR. This series of novel 2-piperazinyl quinoxaline derivatives containing isatin-based thio/semicarbazones and/or Schiff bases of Metformin were evaluated for anticancer activity against both human ovarian and colon-derived tumor cell lines by MTT colorimetric assay. Although most of the investigated hybrid compounds exhibited excellent anti-proliferative activities and high selectivity index (SI) values, the promising compounds N'-[4-(quinoxaline-2-yl)-piperazine-1-yl]methyl-5-chloro-1-H-indole,2,3-dion-3-metformin 4c and N'-[4-(quinoxaline-2-yl)-piperazine-1-yl]methyl-5-bromo-1-H-indole,2,3-dion-3-metformin 4b proved to be the most potent anti-proliferative agents (IC50 values < 1 μM). Molecular docking and dynamics simulation suggest that these hybrid compounds can be wrapped in the catalytic cavity of c-Kit tyrosine kinase receptor and the binding pocket of P-glycoprotein with high scores. Thus, 2-piperazinyl quinoxaline linked isatin-based N-Mannich bases of metformin and/or thio/semicarbazones might be served as suitable candidates for further investigations to develop a new generation of multi-target cancer chemotherapy agents.

Contemporary progress in the green synthesis of spiro-thiazolidines and their medicinal significance: a review

The development of new strategies for the production of nitrogen and sulfur-containing heterocycles remains an extremely alluring but challenging proposition. Among these heterocyclic compounds, spiro-thiazolidines are a distinct class of heterocyclic motifs with an all-encompassing range of pharmaceutical activities such as anti-histaminic, anti-proliferative, anesthetic, hypnotic, anti-fungal, anti-inflammatory, anti-HIV, anthelmintic, CNS stimulant, and anti-viral potentials. Consequently, investigators have produced these heterocycles through diversified intricate pathways as object structures for medicinal studies. Notwithstanding their innumerable manmade solicitations, there is yet no special periodical on MCRs concerning spiro-thiazolidine via green synthesis. Thus, this in-depth review encompasses the excursion of MCRs to spiro-thiazolidines, including the environment-friendly synthetic approaches, reaction situations, rationale behind the optimal selection of catalyst, scope, anticipated mechanism, and biological activities. In this review, we have focussed on the furthermost current developments in spiro-thiazolidine creation under different conditions, such as ionic liquid-assisted, microwave-assisted, on-water, solid-supported acid-catalyzed, asymmetric, and nanocatalyst-assisted syntheses, developed over the last 8 years. This study details works regarding the total amalgamation of spiro-thiazolidines under N- and S-containing heterocycles. Furthermore, this article summarizes the developments of artificially and pharmaceutically important spiro-thiazolidine candidates.

Catalyst-Free, Room-Temperature Accessible Regioselective Synthesis of Spiroquinolines and Their Antioxidant Study

An efficient, regioselective, and environmentally benign approach was established using the multicomponent reaction-based synthesis of novel antioxidant spiroquinoline derivatives such as spiro[dioxolo[4,5-g]quinoline], spiro[dioxino[2,3-g]quinoline], and spiro[pyrazolo[4,3-f]quinoline] by reaction of aryl aldehyde, Meldrum's acid, and amine derivatives under an additive-free reaction in aqueous ethanol. Here, two asymmetric carbon centers, three new C-C bonds, and one C-N bond are developed in the final motif. This synthetic methodology offers excellent yields with an easy workup procedure, high diastereoselectivity [d.r. >50:1 (cis/trans)], admirable atom economy, and low E-factor values. Synthesized spiro compounds were investigated for their in vitro antioxidant activity by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. In the ABTS radical scavenging assay, compounds 4d, 4f, and 4l exhibit excellent potency, and in the DPPH radical scavenging assay, compounds 4a, 4d, 4f, and 4g, exhibit excellent potency.

exo'-Selective Construction of Spirobipyrrolidines by the Silver-catalyzed Asymmetric [3+2] Cycloaddition of Imino Esters with 4-Benzylidene-2,3-dioxopyrrolidines

The unprecedented Ag-catalyzed exo ' -selective [3+2] cycloaddition of imino esters with 4-benzylidene-2,3-dioxopyrrolidines is described. The reaction was efficiently catalyzed by AgOAc/( R , S p )-ThioClickFerrophos (TCF) leading to the construction of the corresponding spirobipyrrolidine scaffolds in excellent enantio- and diastereoselectivities. This reaction is the first example of a silver-catalyzed exo ' -selective asymmetric [3+2] cycloaddition, as well as the first exo ' -selective spirobipyrrolidine construction via a [3+2] cycloaddition process using imino esters. The wide substrate scope of this reaction enabled the preparation of structurally diverse spirobipyrrolidine derivatives, which are attracting attention as targets for drug discovery. Mechanistic studies suggested that the unusual exo ' -selectivity of this reaction is not due to epimerization following the common exo - or endo -selective cycloaddition, but instead is due to a stepwise Michael addition/Mannich sequence with bond rotation.

A novel powerful Choline Chloride – Thiourea /Sulfuric Acid, efficient and recyclable catalyst via microwave‐assisted for the synthesis of Quinazolin- 4(3H)–one derivatives as Antibacterial Agents in green media

Background:

Choline Chloride - Thiourea / Sulfuric Acid is a powerful and efficient green catalyst used for one-pot synthesis of quinazoline-4 (3H) -one derivatives via a reaction between various amines, acetic anhydride, and anthranilic acid under microwave irradiation and solvent-free conditions (4a-q). Microwave irradiation, which is a faster, more cost-effective, less energy-intensive, and more efficient method than conventional heating, has been used to synthesize some quinazolinone derivatives.

Introduction:

For the past ten years, one of the major subjects in synthetic organic chemistry has been green synthesis, which has used efficient and environmentally friendly methods to synthesize biological compounds. The use of catalysts has significant advantages, including ease of preparation and separation, chemical and thermal stability, and environmental friendliness due to features such as reusability, low cost, and efficient, easy workup techniques. Therefore, the mechanism is performed by a non-toxic organic catalyst that uses the least energy and chemical reactants in accordance with the principles of green chemistry and least waste.

Methods:

One-pot and sequential addition methods have been used to synthesize quinazolinone derivatives. In the sequential addition method, the reaction was started by adding acetic anhydride and anthranilic acid to the reaction vessel under microwave irradiation and continued by adding choline chloride thiourea / sulfuric acid as efficient recyclable green catalysts and the desired amine. In vitro, the well diffusion method against different pathogenic strains was used to evaluate the antimicrobial activity of quinazoline-4 (3H) -one derivatives. Pathogenic strains used were Candida albicans ATCC 10231 (yeast), Aspergillus niger ATCC 16404 (fungus), Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 9027 (bacteria) and ATCC 6538, and Staphylococcus aureus S. epidermidis ATCC 12228. Pyrimidine-containing compounds in which the 3-hydroxyl, 2,5-Dimethoxy, 4-bromo, 4 ‐ Methoxy, and 4 ‐ chloro groups are attached to the phenyl ring of pyrimidine exhibit antimicrobial properties.

Results:

In a short reaction time, a variety of biologically active quinazolinone derivatives were synthesized with a high efficiency. According to the results, it was found that with aliphatic amines, the reaction time was shorter and the reaction efficiency was higher. Products synthesized from aromatic amines had more antibacterial properties.

Conclusion:

In this work, a variety of 2-methyl-quinazoline-4 (3H) -one derivatives (4a–q) were synthesized as potent antibacterial agents under microwave irradiation and solvent-free conditions in the presence of ChCl-thiourea / H2SO4 as an efficient, eco-friendly, and recyclable catalyst.

A novel superparamagnetic powerful guanidine-functionalized γ-Fe2O3 based sulfonic acid recyclable and efficient heterogeneous catalyst for microwave-assisted rapid synthesis of quinazolin-4(3H)-one derivatives in Green media

The novel organic–inorganic nanohybrid superparamagnetic (γ-Fe₂O₃@CPTMS–guanidine@SO₃H) nanocatalyst modified with sulfonic acid represents an efficient and green catalyst for the one-pot synthesis of quinazolin-4(3H)-one derivatives via three-component condensation reaction between anthranilic acid, acetic anhydride and different amines under microwave irradiation and solvent-free conditions (4a–q). XRD, FT-IR, FE-SEM, TGA, VSM and EDX were used to characterize this new magnetic organocatalyst. Outstanding performance, short response time (15–30 min), simple operation, easy work-up procedure, and avoidance of toxic catalysts can be regarded as its significant advantages. Moreover, it can be easily separated from the reaction solution through magnetic decantation using an external magnet, and recycled at least six times without notable reduction in its activity.

A novel organic–inorganic nanohybrid superparamagnetic nanocatalyst (γ-Fe₂O₃@CPTMS–guanidine@SO₃H) represents an efficient and green catalyst for the one-pot synthesis of quinazolin-4(3H)-one derivatives via a three-component condensation reaction.