HFIP-mediated multicomponent reactions for the synthesis of fluorescent quinoline-fused pyrroles

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A simple, two‐step process was developed for the easy access of polycyclic pyrrolopyridine derivatives. The first step involves a multicomponent reaction of aryl glyoxal, cyclohexane‐1,3‐dione derivatives and 2‐amino‐1,4‐napthoquinone in AcOH: H2O (1 : 1 v/v) under reflux conditions which led to the formation of 1,5‐diketones in 15 min of reaction time. In the second step, the reaction of ammonium acetate with 1,5‐diketones in AcOH under reflux conditions resulted the formation of polycyclic pyrrolopyridine derivatives. All the products were characterized by FTIR, 1H NMR, 13C NMR and HRMS. The single crystal XRD of one compound was recorded to further confirm the structure of the product. The presence of several bioactive moieties in our product, simple reaction process, metal‐free reaction conditions, easy purification method, and good yields of the products are the notable features of this methodology.

Synthesis of Polycyclic Pyrrolopyridine Derivatives via Multicomponent Synthesis of 1,5‐Diketones

Chaurasia,

Parvin

2024

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Humic Acid: A Promising and Green Bioorganic Catalyst in Organic Syntheses

Swaraj Acharya,

Bhusan Parida

2024

The growing pollution and threat to the environment demand green synthetic methods. Green chemistry mainly focuses on minimizing the waste and utilization of green solvents, energy sources, and catalysts and prefers one‐pot reactions. In this context, humic acid (HA), a natural bioorganic catalyst found in rivers, peat coal and sewage; is a high molecular weight macromolecule containing multifunctional groups, mainly contains quinone, phenolic OH, and COOH groups which make it acidic and activate carbonyl groups by protonation. Owing to its green aspect such as biodegradability, recyclability and reusability, humic acid is considered as sustainable bioorganic catalyst which meets the criteria for industrial requirements. The HA is mild acidic in nature, thus many functional groups tolerate in the HA catalyzed reactions. After few initial reports in 2001 and 2009, the HA catalyzed reactions gained much attention by the organic synthetic community from 2019 in aldol condensation, Knoevenagel condensation, Claisen‐Schmidt reaction, Michael addition, Strecker synthesis, tetrazole synthesis, Hantzsch dihydropyridine synthesis, hydrosilylation of terminal alkenes, hydrogenation, α‐aminophosphonate synthesis, cross coupling reactions such as Heck and Suzuki coupling reactions. Herein we report the comprehensive analysis on the role of HA in organic transformations providing diverse array of molecular scaffolds till date and future perspective.

Visible Light‐Mediated Multicomponent Synthesis of Spirooxindole‐Linked Fused Pyrans: An Eco‐Friendly One‐Pot Strategy

Mondal,

Singh,

Kumari

et al. 2024

A green and efficient method for the preparation of spirooxindole‐linked fused pyrans has been developed utilizing a catalyst‐free visible‐light‐driven one‐pot multicomponent reaction strategy. The reaction was performed in a water and ethanol mixture, using the combination of isatin, malononitrile, and cyclic 1,3‐dicarbonyls such as 4‐hydroxy‐1‐methyl‐2(1H)‐quinolone, 4‐hydroxycoumarin, 4‐hydroxythiocoumarin, or barbituric acid derivatives. This catalyst‐free, environmentally friendly, visible‐light‐driven, and room temperature method is a valuable addition to the synthetic toolbox for constructing complex heterocyclic scaffolds under one‐pot conditions. It holds promise for future applications in medicinal chemistry and drug discovery.