Catalyst-free, ethylene glycol promoted one-pot three component synthesis of 3-amino alkylated indoles via Mannich-type reaction

Synthesis of Indole-Coupled KYNA Derivatives via C–N Bond Cleavage of Mannich Bases

KYNAs, a compound with endogenous neuroprotective functions and an indole that is a building block of many biologically active compounds, such as a variety of neurotransmitters, are reacted in a transformation building upon Mannich bases. The reaction yields triarylmethane derivatives containing two biologically potent skeletons, and it may contribute to the synthesis of new, specialised neuroprotective compounds. The synthesis has been investigated via two procedures and the results were compared to those of previous studies. A possible alternative reaction route through acid catalysis has been established.

Efficient metal-free green syntheses of 4H-chromenes and 3-amino alkylated indoles using a reusable graphite oxide carbocatalyst under aqueous and solvent-free reaction conditions

Graphite oxide was employed as a reusable catalyst for the synthesis of 4H-chromenes and 3-amino alkylated indoles in aqueous and solvent-free reaction conditions.

Catalyst-free and additive-free reactions enabling C-C bond formation: a journey towards a sustainable future

This review focuses on the catalyst- and additive-free C-C bond forming reactions reported mostly from the year 2005 to date. C-C bond forming reactions are highly important as large and complex organic molecules can be derived from simpler ones via these reactions. On the other hand, catalyst- and additive-free reactions are economical, environmentally friendly and less sensitive to air/moisture, allow easy separation of products and are operationally simple. Hence, a large number of research articles have been published in this area. Though a few reviews are available on the catalyst-free organic reactions, most of them were published a few years ago. The current review excludes catalysts as well as additives and is specific to only C-C bond formation. Besides many organic name reactions, catalyst/additive-free C-H functionalizations, coupling reactions and UV-visible-light-promoted reactions are also discussed. Undoubtedly, the contents of this review will motivate readers to do more novel work in this area which will accelerate the journey towards a sustainable future.

Catalyst-free and multicomponent synthesis of 3-aminoalkylated indoles via a Mannich-type reaction: multitargeted anticancer, tyrosinase and α-glucosidase inhibitory activities

3-Aminoalkylated indoles, synthesized via a multicomponent Mannich-like reaction, are evaluated for enzyme inhibition; 5e and 5f are shown to be prospective multitargeted anticancer agents, and the cytotoxic mechanism of action is demonstrated via molecular docking study.

3-Amino-alkylated indoles: unexplored green products acting as anti-inflammatory agents

Aim: Over the years, indole has proved to be a versatile scaffold for the design of molecules acting as anti-inflammatory agents. Materials & Methods: A small library of 3-amino-alkylated indoles has been obtained by an optimized Mannich green approach. The anti-inflammatory activity of the new 3-amino-alkylated indoles, GLYC 0–10, was evaluated in RAW 264.7 macrophages. Results: The anti-inflammatory activity of the new 3-amino-alkylated indoles, GLYC 0–10, was evaluatedn and, among them, GLYC 4, 5 and 9 displayed the greatest inhibitory effects on nitric oxide production, with IC50 values of 5.41, 4.22 and 6.3 μM, respectively. Conclusion: Our outcomes, overall, highlight the importance of the indole substitution in the anti-inflammatory activity of these compounds, exerted by acting on the interlinked NF-κB/ERK1/2 pathways.

Ethylene glycol promoted catalyst-free pseudo three-component green synthesis of bis(coumarin)s and bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s

An ethylene glycol promoted catalyst-free practically efficient and sustainable approach has been developed for the synthesis of several benzylidene-bis-(4-hydroxycoumarin)s and 4,[Formula: see text]-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s by the pseudo three-component reaction of an aldehyde with 4-hydroxycoumarin and 3-methyl-1-phenylpyrazol-5-one, respectively. Inexpensive, non-toxic, and easily available ethylene glycol used as the reaction solvent and promoter renders an efficient protocol in terms of catalyst-free reaction conditions, short reaction time, high yield, practical utility, and green approach.

(+)-CSA Catalyzed Multicomponent Synthesis of 1-[(1,3-Thiazol-2-ylamino)methyl]-2-naphthols and Their Ring-Closure Reaction under Ultrasonic Irradiation

New 1-[(1,3-thiazol-2-ylamino)methyl]-2-naphthols were obtained by condensation of 2-aminothiazole, aromatic aldehydes, and 2-naphthol in the presence of (+)-camphor-10-sulfonic acid ((+)-CSA) as an effective catalyst under ultrasound-promoted solvent-free conditions. The 1-[(1,3-thiazol-2-ylamino)methyl]-2-naphthol derivatives were converted in ring-closure reaction with formaldehyde to the corresponding naphthoxazine derivatives.

Montmorillonite K10 catalyzed multi component reactions (MCR): synthesis of novel thiazolidinones as anticancer agents

Montmorillonite K10 is a suitable catalyst in a multicomponent reaction involving an aldehyde, an amine, and thioglycolic acid in N,N-dimethylformamide as solvent at moderate (50°C) to reasonably high (120°C) temperatures to form thiazolidinones. The reaction involves easy workup and purification. Several thiazolidinones were prepared. In particular, campholenic aldehyde obtained from α-pinene was used to synthesize potentially bioactive thiazolidinones. All products were characterized by IR, 1H NMR, and mass spectra. Preliminary anticancer screening tests revealed that two compounds show anticancer activity and can be taken up for further screening.

Facile construction of 3-indolochromenes and 3-indoloxanthenes via EDDF catalyzed one-pot three component reactions

EDDF–ethylene glycol, an ambiphilic catalytic system has been employed for the mild and rapid synthesis of various 3-indolochromenes and 3-indoloxanthenesviaa one-pot MCR. Besides recyclability of the catalyst, the present method circumvents the formation of any by-products.

Cu(0)@Al2O3/SiO2 NPs: an efficient reusable catalyst for the cross coupling reactions of aryl chlorides with amines and anilines

The C–N cross coupling reaction of aryl chlorides with various alkyl/aryl amines catalyzed by copper nanoparticles impregnated on alumina/silica support (Cu(0)@Al₂O₃/SiO₂) was investigated and the catalyst showed excellent reactivity and efficacy.

C3 functionalization of indolizines via In(iii)-catalyzed three-component reaction

Post-functionalization at the C3 position of indolizines via In(iii)-catalyzed three-component coupling reaction with amines and aldehydes allowed rapid access to a new class of indolizines with diverse functional groups at the C3 position in good to excellent yields.