Solvent-Controlled Divergent Cyclization of 3-Ylideneoxindoles with Ethyl 2-Diazoacetate: Access to Spirocyclopropyl and Spiropyrazolines Oxindoles

Herein a catalyst-free solvent-controlled method for the divergent synthesis of spirocyclopropyl and spiropyrazoline oxindoles from 3-ylideneoxindoles and ethyl diazoacetate was developed. With ClCH2CH2Cl as the solvent, spirocyclopropyl oxindoles were obtained in moderate to excellent yields, whereas the use of MeOH as solvent afforded spiropyrazoline oxindoles in moderate to good yields. The readily available substrates, simple operation and various product transformations further highlighted the utility of this method.

Microwave-assisted protocol towards synthesis of heterocyclic molecules: a comparative analysis with conventional synthetic methodologies (years 2019-2023): a review

Microwave-assisted protocols have become extensively accepted across various scientific and technological domains because of their numerous advantages, shorter reaction times, higher yields, and often milder reaction conditions. In this review, we focus on the synthesis of N, O, and S-containing heterocyclic structural cores, crucial in the development of pharmaceuticals, agrochemicals, and materials science following through conventional and microwave method via eliminating the side products and enhances the product yield that is nowadays the biggest barrier for a synthetic chemist. The major findings emphasizes the substantial advantages of microwave-assisted techniques over conventional synthetic protocols. This comparative study underscores the potential of microwave-assisted techniques to revolutionize heterocyclic compound synthesis, providing insights into optimizing reaction conditions and expanding the scope of chemical synthesis in industrial applications.

Green synthesis of novel spiropyrazoline-indolinones in neutral deep eutectic solvents and DFT studies

Novel spiropyrazoline-indolinones (4a-t) have been synthesized successfully in neutral deep eutectic solvents by reacting 5-Cl/Br-isatin (1a-b) with aromatic ketones (2a-b) and a variety of substituted hydrazines (3a-e) in good to excellent yields. This eco-friendly straightforward synthetic protocol discloses good functional group compatibility. The conventional synthetic approach was compared with the greener route of microwave-assisted synthesis of spiropyrazolines using ethanol. This approach utilized mild reaction conditions which furnished high yields in short reaction time employing one pot two-step multicomponent. All new compounds were structurally confirmed by detailed spectroscopic analysis and density functional theory calculations. This method provides efficient access to spiropyrazole derivatives using biodegradable and green solvent.

Lewis acid catalyzed spiro annulation of (Z)-3-amino-acrylates with 2-amino arylbenzamides: one-pot synthesis of pyrrole-quinazoline hybrids

The one-pot domino reaction of ethyl (Z)-3-amino-3-phenylacrylates with 2-amino-N-alkyl/arylbenzamides under Lewis acid catalysis was described as an effective way to construct novel spiro [pyrrole-3,2'-quinazoline] carboxylate derivatives. By combining substituted alkyl/aryl amides with spiro annulated 1H-pyrrole-2,3-diones, this method provides a novel way for producing spiro pyrrole derivatives in good to excellent yields. The current procedure has a number of benefits, including quicker reaction times, a broad tolerance range for functional groups, and the ability to synthesize 2,3-dihydroquinazolin-4(1H)-ones that are of biological importance and take part in organic transformations. This is the first use of molecular hybridization involving linking with pyrrole derivatives and dihydroquinazolin-4(1H)-ones.

Organocatalytic Regioselective [3+2] Annulation of Morita-Baylis-Hillman Carbonates with Azonaphthalenes: An Efficient Access to 3-Spiropyrazole- 2-oxindoles

Background:

A cheap and commercially available organocatalyst, 4-dimethylaminopyridine was successfully employed in the regioselective [3+2] cycloaddition of isatin-derived Morita-Baylis- Hillman carbonates with azonaphthalenes for the construction of 3-spiropyrazole-2-oxindoles in excellent yields under mild conditions.

Methods:

In the presence of 4-dimethylaminopyridine with a loading of 10 mol%, a series of isatinderived Morita-Baylis-Hillman carbonates reacted smoothly with azonaphthalenes in dichloromethane at room temperature to furnish 3-spiropyrazole-2-oxindoles in 72-98% yield.

Result and Conclusion:

In summary, we have developed reasonably cheap and commercially available 4-dimethylaminopyridine-mediated regioselective [3+2] annulations between isatin-derived Morita- Baylis-Hillman carbonates and azonaphthalenes for the construction of 3-spiropyrazole-2-oxindoles under mild conditions.

Microwave-accelerated diastereoselective catalyst-free one-pot four-component synthesis of 2-(N-carbamoylacetamide)-substituted 2,3-dihydrothiophenes in glycerol

In the current study, glycerol was successfully employed as a nonvolatile, non-toxic, non-flammable, biodegradable, very cheap, easily accessible, and efficient reaction medium for the microwave-enhanced diastereoselective synthesis of 2-(N-carbamoylacetamide)-substituted 2,3-dihydrothiophenes via a catalyst-free one-pot four-component reaction. A versatile range of starting materials were used, and diverse products were obtained in good to excellent yields and very short reaction times. Moreover, the reaction medium was recovered and reused several times without any loss of the efficiency.

A practical green approach to diversified spirochromene/spiropyran scaffolds via a glucose–water synergy driven organocatalytic system

Development of a versatile, new glucose–water organocatalytic system promoted, one pot, practical green method for the synthesis of diversified spirochromenes/spiropyrans is reported.

1,3-Dipolar Cycloaddition Reactions for the Synthesis of Novel Oxindole Derivatives and Their Cytotoxic Properties

The multicomponent reaction between isatin, amino acid, but-2-ynedioates, and phenacyl bromide has been developed using microwave irradiation under catalyst and base-free conditions in aqueous medium. This synthetic protocol is useful for the synthesis of various functionalized spirooxindole derivatives. This MCR exhibits a broad substrate scope with excellent yields and shorter reaction time. Additionally the synthesized spirooxindole derivatives were evaluated for their anticancer activity against three human cancer cell lines: MCF-7 (breast), A549 (lung), and HeLa cervical. Most of the compounds showed moderate to potent cytotoxic activity against the tested cell lines.

Bioorganopromoted green Friedländer synthesis: a versatile new malic acid promoted solvent free approach to multisubstituted quinolines

An efficient new strategy for the green synthesis of a variety of polysubstituted quinolines, using the Friedländer approach is reported, employing malic acid as a catalyst in organic synthesis for the first time.

Synthesis of spiropyrazoline oxindoles by a formal [4 + 1] annulation reaction between 3-bromooxindoles and in situ-derived 1,2-diaza-1,3-dienes

A formal [4 + 1] annulation reaction of 3-bromooxindoles and in situ-derived 1,2-diaza-1,3-dienes has been developed to provide an efficient route to various spiropyrazoline oxindoles with high yields.

Facile Synthesis of Azaarene-Substituted Hydroxycoumarins Possessing High Biological Activities via Three-Component C(sp(3))-H Functionalization

An unprecedented three-component C(sp(3))-H functionalization of 2-alkylazaarenes with aryl aldehydes and 4-hydroxycoumarins was realized, providing azaarene-substituted 3-benzyl-4-hydroxycoumarins in good to excellent yields. These new target compounds displayed broad-spectrum antibacterial activities, providing a new type of antibacterial skeleton.

A catalyst free, multicomponent-tandem, facile synthesis of pyrido[2,3-d]pyrimidines using glycerol as a recyclable promoting medium

An efficient and green, one-pot synthesis of pyrido[2,3-d]pyrimidines, a biologically important heterocyclic scaffold, using glycerol as a promoter cum solvent.

A catalyst-free, one-pot multicomponent synthesis of spiro-benzimidazoquinazolinones via a Knoevenagel–Michael-imine pathway: a microwave assisted approach

A multi-component route for the synthesis of spiro-benzimidazoquinazolinones was developed and its mechanism was studied.