Microwave-induced calcium(II) chloride-catalyzed Paal–Knorr pyrrole synthesis: a safe, expeditious, and sustainable protocol

Aghapoor, Kioumars; Mohsenzadeh, Farshid; Darabi, Hossein Reza; Rastgar, Saeed

doi:10.1007/s11164-018-3355-7

Cited by 19 publications

(3 citation statements)

References 63 publications

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“…According to previous literature, the dicarbonyl compound can be activated by Lewis acidic, metal site, and amine function [18,25,26,36–38] . On this basis, we proposed that the catalytic efficiency of Zn 2 (OAB) for pyrroles synthesis at mild conditions can be attributed to the synergistic cooperation between the Lewis acidic Zn sites and the −NH− groups derived from the H 4 OAB linker.…”

Section: Resultsmentioning

confidence: 93%

“…According to previous literature, the dicarbonyl compound can be activated by Lewis acidic, metal site, and amine function. [18,25,26,[36][37][38] On this basis, we proposed that the catalytic efficiency of Zn 2 (OAB) for pyrroles synthesis at mild conditions can be attributed to the synergistic cooperation between the Lewis acidic Zn sites and the À NHÀ groups derived from the H 4 OAB linker. As depicted in Figure 7, Zn sites interact with the carbonyl groups of the dicarbonyl compound while the À NHÀ moieties from oxamide functionality activate the oxygen atoms of the dicarbonyl compound through hydrogen bonding, resulting in activated carbonyl complexes 1A, 1B.…”

Section: Reaction Mechanismmentioning

confidence: 99%

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A New Zinc‐Based Metal‐Organic Framework for Catalytic Synthesis of N‐Substituted Pyrroles

Tran

Nguyen

2022

ChemistrySelect

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A new zinc‐based metal‐organic framework (MOF) Zn2(OAB) [OAB4−=4,4′‐(oxalylbis(azanediyl))bis(2‐oxidobenzoate)), analogous to a well‐studied MOF‐74 structure, was solvothermal synthesized and characterized. The Zn2(OAB) frameworks exhibited accessible mesopore channels (24 Å) and high porosity (SBET=3115 m2 g−1). The presence of the high density of both Lewis acidic Zn sites and −NH− groups derived from the organic OAB4− unit make Zn2(OAB) a promising candidate for catalysis Paal‐Knorr N‐substituted pyrroles synthesis. As such, Zn2(OAB) exhibited excellent catalytic activity in the synthesis of 2,5‐dimethyl‐1‐phenyl‐1H‐pyrrole with a yield of 96 % at 70 °C for 16 min. Notably, the catalytic activity of Zn2(OAB) outperformed that of homogeneous, heterogeneous catalysts, and representative Zn‐based MOFs (ZIF‐8, MOF‐5, Zn‐MOF‐74). The Zn2(OAB) was also demonstrated to be reused up to eight times without noteworthy loss of its activity.

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Section: Resultsmentioning

confidence: 93%

Section: Reaction Mechanismmentioning

confidence: 99%

A New Zinc‐Based Metal‐Organic Framework for Catalytic Synthesis of N‐Substituted Pyrroles

Tran

Nguyen

2022

ChemistrySelect

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“…These protocols offer advantages, such as catalyst reusability and a simple workup procedure. Additionally, metal halides showed outstanding performance as Lewis acid catalysts in the Paal-Knorr reaction (Aghapoor et al, 2018;Rahmatpour, 2012;Zhang et al, 2008). Furthermore, a variety of Brønsted acid catalysts, such as acetic acid (Cheng et al, 2013), phosphoric acid (Zhang et al, 2017), sulfamic acid (Luo et al, 2008) and p-toluenesulfonic acid (Bharadwaj et al, 2004), among others, have been employed successfully.…”

Section: Introductionmentioning

confidence: 99%

Crystallographic, spectroscopic and thermal studies of 1-(4-bromophenyl)-5-(2,5-dimethyl-1H-pyrrol-1-yl)-3-methyl-1H-pyrazole

Moreno-Suárez,

Avila-Acosta,

Sánchez-Ramírez

et al. 2023

Acta Crystallogr C Struct Chem

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The new title pyrrole–pyrazole derivative, C16H16BrN3, was synthesized through a citric acid-catalyzed Paal–Knorr reaction between acetonylacetone and 1-(4-bromophenyl)-3-methyl-1H-pyrazol-5-amine under mild reaction conditions. This synthetic protocol is noteworthy for its utilization of stoichiometric amounts of the reactants, an ecofriendly solvent and a cost-effective, non-toxic and biodegradable organocatalyst. A comprehensive understanding of the molecular structure was gained through spectroscopic, thermal and X-ray crystallographic analyses. The crystal structure is characterized by weak interactions, where only C—H...π connections contribute to the hydrogen-bond contacts. The supramolecular assembly is controlled by dispersion forces. However, the energy frameworks demonstrate that these forces act in three dimensions, providing enough stability, as observed in TGA–DSC (thermogravimetric analysis–differential scanning calorimetry) studies.

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Microwave‐Assisted Synthetic Pathways of Pyrrole: A Comprehensive Review

Yadav,

Sanduja,

Kumar

et al. 2024

Asian J Org Chem

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Microwave synthesis is a sustainable and eco‐friendly method for producing novel organic compounds, offering faster reactions, higher yields, and improved purity compared to traditional techniques. Efficiency is increased by the uniform heating caused by microwave radiation, especially for the synthesis of heterocyclic compound and their derivatives. Owing to have important biological and therapeutic qualities, a number of microwave‐assisted synthetic methods of pyrroles have been developed that produce better results than the conventional reported method. In view of this, the present review emphasizes solvent‐free and catalyst‐free methods for the microwave‐assisted synthesis of pyrrole and its fusion with other heterocycles such as furan, pyridine, beta‐lactam, and indole. A comparison between traditional and microwave‐assisted techniques is given in terms of reagents, covering yield, waste minimization, solvents, and catalysts.

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Microwave-induced calcium(II) chloride-catalyzed Paal–Knorr pyrrole synthesis: a safe, expeditious, and sustainable protocol

Cited by 19 publications

References 63 publications

A New Zinc‐Based Metal‐Organic Framework for Catalytic Synthesis of N‐Substituted Pyrroles

A New Zinc‐Based Metal‐Organic Framework for Catalytic Synthesis of N‐Substituted Pyrroles

Crystallographic, spectroscopic and thermal studies of 1-(4-bromophenyl)-5-(2,5-dimethyl-1H-pyrrol-1-yl)-3-methyl-1H-pyrazole

Microwave‐Assisted Synthetic Pathways of Pyrrole: A Comprehensive Review

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