One pot four-component reaction for the efficient synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylate derivatives

Review on advancements of pyranopyrazole: synthetic routes and their medicinal applications

Pyranopyrazoles are among the most distinguished, biologically potent, and exciting scaffolds in medicinal chemistry and drug discovery. Synthesis and design of pyranopyrazoles using functional modifications via multicomponent reactions (MCRs) are thoroughly found in synthetic protocols by forming new C-C, C-N, and C-O bonds. This review aims to focus on the biological importance of pyranopyrazoles as well as on a diverse synthetic approach for their synthesis using various catalytic systems such as acid-catalyzed, base-catalyzed, ionic liquids and green media-catalyzed, nano-particle-catalyzed, metal oxide-supported catalysts, and silica-supported catalysts. In this review, we have summarized data on the advancements in synthesizing pyranopyrazole from the last two decades to the mid-2023 and research papers describing the importance of these scaffolds. This review will be significant for synthetic organic chemists and researchers working in organic chemistry.

Unveiling the Origin of the Selectivity and the Molecular Mechanism in the [3+2] Cycloaddition Reaction of N-aryl-C-carbamoylnitrone with N-arylitaconimide

The [3+2] cycloaddition reaction of N-aryl-C-carbamoylnitrone (nitrone 1) with N-arylitaconimide (ethylene 2) was computationally studied using the B3LYP/6-31G(d) level of theory. An analysis of the different energetic profiles and the transition states’ optimized structures clearly indicated that this 32CA occurred through a non-polar, asynchronous, one-step mechanism, favoring the formation of the ortho–endo cycloadduct, as observed experimentally. The analysis of the reactivity indices derived from the conceptual DFT explains well the low polarity of this 32CA reaction. Parr functions and a dual reactivity descriptors analysis correctly explained the regioselectivity ortho of this 32CA reaction. Solvent effects did not modify the obtained selectivity but it increased the activation energies and decreased the exothermic character of this 32CA reaction. A thermodynamic parameters analysis indicated that this 32CA wascharacterized by an ortho regioselectivity and endostereoselectivity and exothermic and exergonic characters.

SLS-catalyzed Multi-component One-pot Reactions for the Convenient Synthesis of Spiro[indoline-3,4’-pyrano [2,3-c]pyrazole] Derivatives

Background,Objective: :

spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles] derivatives are an important heterocyclic compounds. These compounds shows wide range of biological properties and exhibits varied pharmaceutical applications. Pyranopyrazoles, which are basically fused heterocyclic compounds and act as vasodilators, hypertensive, hypoglycaemic, and anticancer agents.

Methods:

An efficient and micelle-promoted surfactant catalyzed synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles] derivatives have been achieved via one-pot four-component reaction of hydrazine hydrate (phenyl hydrazine), ethyl acetoacetate, malononitrile (ethyl cyanoacetate) and isatin under thermal conditions (at 60°C) in water as a solvent.

Results:

Sodium lauryl sulphate (SLS) used has been found to be an efficient and green catalyst. The compounds reported during this work were obtained in excellent yield, in a short duration of time and ease of work up. They were purified by recrystalization from ethanol, and also the synthesized compounds were characterized by various spectroscopic techniques.

Conclusion:

The method offers several advantages such as safe, cost-effective and catalyst easily recovered and reused for a minimum of five cycles, that confirms its good stability. Short reaction times, high yield and usage of eco-friendly catalyst and solvent are the key features of this methodology.

A facile and efficient procedure for one-pot four-component synthesis of polysubstituted spiro pyrano[2,3-c]pyrazole and spiro 1,4-dihydropyridine catalyzed by a Dabco-based ionic liquid under mild conditions

Spiro pyrano[2,3-c]pyrazoles and spiro 1,4-dihydropyridines were obtained in high yields from different amine components under Dabco-based ionic liquid catalysis.

Synthesis of spiro heterocyclic systems from 2-(3-oxoisobenzofuran-1(3H)-ylidene)malononitrile and binucleophiles

The reaction of 2-(3-oxoisobenzofuran-1(3 H)-ylidene)malononitrile, generated from phthalic anhydride and malononitrile, with different binucleophiles led to the formation of spiro heterocycles possessing a phthalide ring system in good yields.

Efficient catalytic application of a binary ionic liquid mixture in the synthesis of novel spiro[4H-pyridine-oxindoles]

Novel pyrazole-fused spiro[4H-pyridine-oxindoles] were synthesized under the catalysis of the binary ionic liquid mixture [1,1,3,3-tetramethylguanidinium chloride][1-methylimidazolium-3-sulfonate] in solvent-free conditions.

BF3 bonded nano Fe3O4 (BF3/MNPs): an efficient magnetically recyclable catalyst for the synthesis of 1,4-dihydropyrano[2,3-c]pyrazole derivatives

1,4-Dihydropyrano[2,3-c]pyrazole derivatives were efficiently synthesized in a simple one-pot three-component reaction of various aldehydes with malononitrile and a 2-pyrazoline-5-one in the presence of BF₃/MNPs as a novel nanostructured, heterogeneous and reusable catalyst.

Rapid and efficient one-pot synthesis of spiro[indoline-3,4'-pyrano[2, 3-c]pyrazole] derivatives catalyzed by l-proline under ultrasound irradiation

A rapid and efficient ultrasound-promoted one-pot synthesis of spiro[indoline-3,4'-pyrano[2,3-c]pyrazole] derivatives is described here. The reaction of substituted phenylhydrazine and dialkyl acetylenedicarboxylate with substituted isatin and malononitrile is catalyzed by l-proline to give good-to-excellent yields in water/ethanol (v/v, 1:1) at room temperature.

A novel one pot four-component reaction for the efficient synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylate and trifluoromethylated spiro[indole-3,4′-pyrano[2,3-c]pyrazole] derivatives using recyclable PEG-400

A novel, simple and efficient synthetic protocol has been developed via a one pot, four-component reaction using recyclable PEG-400.

Ultrasound assisted multicomponent reactions: a green method for the synthesis of highly functionalized selenopyridines using reusable polyethylene glycol as reaction medium

A simple and benign one-pot protocol for the synthesis of 2-amino selenopyrindine derivatives 4 has been developed using ultrasound assisted multicomponent reactions of aldehydes, malononitrile and benzeneselenol in PEG-400.

One-pot four-component reaction for convenient synthesis of functionalized 1-benzamidospiro[indoline-3,4'-pyridines]

The one-pot four-component reaction of benzohydrazide (2-picolinohydrazide), acetylenedicarboxylate, isatins and malononitrile (ethyl cyanoacetate) with triethylamine as base catalyst afforded functionalized 1-benzamidospiro[indoline-3,4'-pyridines] in good yields. (1)H NMR spectra indicated that an equilibrium of cis/trans-conformations exist in the obtained products.

Multicomponent reactions for facile access to coumarin-fused dihydroquinolines and quinolines: synthesis and photophysical studies

A three-component reaction of 4-hydroxycoumarin, aldehydes and aromatic amines in the presence of catalytic amounts of Bi(OTf)₃ is reported. Photophysical studies of these molecules showed that coumarin-fused dihydroquinolines exhibit significant quantum yields.

L-proline catalyzed multicomponent reactions: facile access to 2H-benzo[g]pyrazolo[3,4-b]quinoline-5,10(4H,11H)-dione derivatives

Three component reaction of 2-hydroxy 1,4-naphthoquinones, aldehydes, and aminopyrazoles in the presence of a catalytic amount ofl-proline has been described for the synthesis of a series of 2H-benzo[g]pyrazolo[3,4-b]quinoline-5,10(4H,11H)-dione derivatives.

“On-water” synthesis of novel trisubstituted 1,3-thiazolesviamicrowave-assisted catalyst-free domino reactions

A clean, efficient and catalyst-free multicomponent domino reaction of arylglyoxals, cyclic 1,3-dicarbonyls and thioamides in aqueous media under microwave conditions is reported.