A regio- and stereoselective 1,3-dipolar cycloaddition for the synthesis of novel spiro-pyrrolothiazolyloxindoles and their antitubercular evaluation

Baker’s yeast catalyzed one-pot synthesis of bioactive 2-[benzylidene(or pyrazol-4-ylmethylene)hydrazono]-1,3-thiazolidin-4-one-5-yl-acetic acids

An efficient and simple one-pot protocol has been developed for synthesis of substituted derivatives of 2-hydrazono-4-thiazolidinone-5-acetic acids 4a–j and 6a–g by cyclocondensation of aryl/pyrazolyl aldehyde, thiosemicarbazide and maleic anhydride in acetonitrile in the presence of readily available whole cell biocatalyst, baker’s yeast (Saccharomyces cerevisiae). The reaction is enhanced by ultrasonication.

One-pot three-component synthesis and oxidation of functionalized tetrahydrobenzo[d]pyrrolo[2,1-b]thiazoles

Triethylamine-promoted cycloaddition reactions of N-phenacyl and N-alkoxycarbonylmethylbenzothiazolium bromides with aromatic aldehydes and malononitrile (ethyl cyanoacetate, pivaloylacetonitrile) in ethanol afforded functionalized tetrahydrobenzo[d]pyrrolo[2,1-b]thiazoles in good yields and various diastereoselectivity. The oxidation reaction of the functionalized tetrahydrobenzo[d]pyrrolo[2,1-b]thiazoles with DDQ in different solvents resulted in diverse benzothiazole derivatives and benzo[d]pyrrolo[2,1-b]thiazoles. The reaction mechanism and the stereochemistry of this tandem [3 [Formula: see text] 2] cycloaddition reaction and sequential oxidation reaction are illustrated based on analysis of the reactive intermediates and obtained products.

A Facile One-Pot Construction of Succinimide-Fused Spiro[Pyrrolidine-2,3'-Oxindoles] via 1,3-Dipolar Cycloaddition Involving 3-Amino Oxindoles and Maleimides

Increasing interests have been invested in the development of synthetic strategies toward the construction of spiro[pyrrolidine-2,3'-oxindole], which is the core structural skeleton in some compounds with diverse biological activities. In this work, an efficient diastereoselective 1,3-dipolar cycloaddition reaction of azomethine ylides generated in situ from 3-amino oxindoles and aldehydes with maleimides has been described. The protocol provides a facile and efficient access to structurally diverse succinimide-fused spiro[pyrrolidine-2,3'-oxindole] compounds in good to high yields (up to 93%) with moderate to excellent diastereoselectivities (up to >95:5). The relative stereochemistry of cycloaddition products has been assigned by X-ray diffraction analysis.

Green synthesis of new pyrrolidine-fused spirooxindoles via three-component domino reaction in EtOH/H2O

An efficient, green and sustainable approach for the synthesis of novel polycyclic pyrrolidine-fused spirooxindole compounds was developed. The synthesis included a one-pot, three-component, domino reaction of (E)-3-(2-nitrovinyl)-indoles, isatins and chiral polycyclic α-amino acids under catalyst-free conditions at room temperature in EtOH–H₂O. The salient features of this methodology are eco-friendliness, high yields and the ease of obtaining target compounds without the involvement of toxic solvents and column chromatography. These novel polycyclic pyrrolidine-fused spirooxindoles provide a collection of structurally diverse compounds that show promise for future bioassays and medical treatments.

An efficient, green and sustainable approach was developed for the synthesis of novel polycyclic pyrrolidine-fused spirooxindole compounds.

Ultrasound-assisted one-pot multicomponent 1,3-dipolar cycloaddition strategy: combinatorial synthesis of spiro-acenaphthylene-S,S-acetal and 2H-pyranone derivatives

The stereo/regio/chemoselective syntheses of a library of novel spiro[acenaphthylene-1,3′-pyrrolizin]-2-one and spiro[acenaphthylene-1,5′-pyrrolo[1,2-c]thiazol]-2-one have been achieved through 1,3-dipolar cycloaddition.

Effective and diastereoselective preparation of dispiro[cyclopent-3′-ene]bisoxindoles via novel [3 + 2] annulation of isoindigos and MBH carbonates

Efficient, one-step preparation of highly steric dispiro[cyclopent-3′-ene]bisoxindoles with two all-carbon quaternary spirocenters and three adjacent cycles in excellent yields and diastereoselectivities under mild conditions.

Eco-friendly polyethylene glycol (PEG-400): a green reaction medium for one-pot, four-component synthesis of novel asymmetrical bis-spirooxindole derivatives at room temperature

PEG-400 has been used as a green and biodegradable polymeric solvent for the one-pot, two-step, multi-component synthesis of novel asymmetrical bis-spirooxindole derivatives by the reaction of N-alkyl isatin, isatin derivatives, alkylmalonates and C–H activated carbonyl compounds in the presence of K₂CO₃ at room temperature. Using this procedure, all the products were obtained in good to excellent yields.

PEG-400 has been used for the synthesis of novel asymmetrical bis-spirooxindoles by the reaction of N-alkyl isatin, isatin derivatives, alkylmalonates and C–H activated carbonyl compounds in the presence of K₂CO₃ at room temperature.

Catalytic synthesis of 3-aminooxindoles via addition to isatin imine: an update

3-Substituted-3-aminooxindoles have attracted the attention of organic chemist to develop different synthetic methodologies for their synthesis using catalysts. This review covers the recent developments.

Catalytic asymmetric construction of spiropyrrolidines via 1,3-dipolar cycloaddition of azomethine ylides

In this review, recent progress on the catalytic enantioselective synthesis of chiral spiropyrrolidine derivatives via 1,3-dipolar cycloaddition of azomethine ylides has been discussed.

Molecular Hybridization-Guided One-Pot Multicomponent Synthesis of Turmerone Motif-Fused 3,3'-Pyrrolidinyl-dispirooxindoles via a 1,3-Dipolar Cycloaddition Reaction

Described herein is the development of a facile and efficient methodology for the synthesis of novel turmerone motif-fused 3,3′-pyrrolidinyl-dispirooxindoles 3–5 via a multicomponent 1,3-dipolar cycloaddition of dienones 2 with azomethine ylides (thermally generated in situfrom isatins and proline or thioproline or sarcosine). Products bearing four or three consecutive stereocenters consist of two oxindole moieties and a pyrrolidinyl core, including vicinal spiroquaternary stereocenters fused in one ring structure were smoothly obtained in high yields (up to 93% yield) with good diastereoselectivity (up to >20:1). Another valuable application of this method was for the design of new hybrid architectures for biological screening through the adequate fusion of these sub-units of turmerone and 3,3′-pyrrolidinyl-dispirooxindole, generating drug-like molecules.

Multicomponent synthesis of spiropyrrolidine analogues derived from vinylindole/indazole by a 1,3-dipolar cycloaddition reaction

A new series of spiropyrrolidine compounds containing indole/indazole moieties as side chains have been accomplished via a one-pot multicomponent synthesis. The method uses the 1,3-dipolar cycloaddition reaction between N-alkylvinylindole/indazole and azomethine ylides, prepared in situ from cyclic/acyclic amino acids. The 1,3-dipolar cycloaddition proceeds efficiently under thermal conditions to afford the regio- and stereospecific cyclic adducts.

Synthesis of Functionalized 3-Spiro[cyclopropa[a]pyrrolizine]- and 3-Spiro[3-azabicyclo[3.1.0]hexane]oxindoles from Cyclopropenes and Azomethine Ylides via [3 + 2]-Cycloaddition

3-Spiro[cyclopropa[a]pyrrolizine]- and 3-spiro[3-azabicyclo[3.1.0]hexane]oxindoles were prepared in moderate to high yields via one-pot three-component reactions using substituted isatins, α-amino acids, and cyclopropenes. The key step is an intramolecular [3 + 2]-cycloaddition reaction of an in situ generated azomethine ylide onto a cyclopropene. Both N-substituted and N-unsubstituted α-amino acids, dipeptide Gly-Gly, and also benzylamine were used as the amine component for the azomethine ylide generation. The anticancer activity of some of the obtained compounds against human leukemia K562 cell line was evaluated by flow cytometry in vitro.

Synthesis of 2,3′-spirobi[indolin]-2-ones enabled by a tandem nucleophilic benzylation/C(sp2)–N cross-coupling reaction sequence

This study provides an efficient strategy for the construction of spiro[pyrrolidin-3,2′-oxindoles] and represents a new perspective for the synthesis of spirocyclic oxindoles.

One-Pot Access to a Library of Dispiro Oxindole-pyrrolidine/pyrrolothiazole-thiochromane Hybrids via Three-Component 1,3-Dipolar Cycloaddition Reactions

A library of novel dispiro compounds containing oxindole pyrrolidine/oxindolopyrrolothiazole-thiochroman-4-one hybrid frameworks has been synthesized in a fully regio- and stereoselective fashion by the three-component 1,3-dipolar cycloaddition of azomethine ylides generated in situ from the condensation of isatins and secondary amino acids (sarcosine/l-thioproline) with 3-arylidenethiochroman-4-ones. This experimentally simple protocol provides good yields of structurally complex, biologically relevant heterocycles in a single operation.

A facile and green approach for the synthesis of spiro[naphthalene-2,5′-pyrimidine]-4-carbonitrile via a one-pot three-component condensation reaction using DBU as a catalyst

A series of novel spiro[naphthalene-2,5′-pyrimidine]-4-carbonitriles were synthesized using 1,3-dimethylbarbituric acid, aldehydes and cyclohexylidene malononitrile in presence of DBU. The structures were confirmed by spectral data and X-Ray crystallography.

Insights into the unexpected chemoselectivity in Brønsted acid catalyzed cyclization of isatins with enaminones: convenient synthesis of pyrrolo[3,4-c]quinolin-1-ones and spirooxindoles

Chemoselective [1+2+3] vs. cascade cyclization has been developed by switching Brønsted acid, offering a divergent synthesis of pyrrolo[3,4-c]quinolin-1-ones and spirooxindoles.

Diastereoselective synthesis of novel tetra-and pentacyclic annulated coumarino-δ-sultam pyrrolidine, pyrrolizidine, pyrrolothiazole and isoxazolidine derivatives via intramolecular 1,3-dipolar cycloadditions

A facile and efficient strategy towards the novel tetra- and pentacyclic annulated coumarino-δ-sultam pyrrolidine, pyrrolizidine, pyrrolothiazole and isoxazolidine via intramolecular 1,3-dipolar cycloadditions of is described.

Inorganic-organic hybrid silica based tin complex as a novel, highly efficient and recyclable heterogeneous catalyst for the one-pot preparation of spirooxindoles in water

In the present study, a tin complex immobilized on silica gel as a novel, green, highly efficient and heterogeneous reusable catalyst was synthesized by grafting 2-amino benzamide onto the silica gel surface as a result of the reaction between isatoic anhydride and 3-aminopropyl-functionalized silica gel, followed by complexing with tin chloride. The resulting organic-inorganic hybrid material was evaluated in the one-pot three-component synthesis of spiro[indoline-pyrazolo[4',3':5,6]pyrido[2,3-d]pyrimidine]trione derivatives in water via the condensation reaction of isatins, barbituric acids, and 1H-pyrazol-5-amines. All the reactions were completed in short reaction times and all the products were obtained in high to excellent yields with high purity. In addition, the synthesized novel catalyst could be separated from the reaction mixture by simple filtration and can be reused up to seven runs without significant loss in activity.

Highly diastereoselective synthesis of imidazolidine-dispirooxindoles via three-component [3 + 2] cycloadditions of isatins, 2-(aminomethyl)pyridine and isatin-based imines

In the presence of Et₃N, the [3 + 2] cycloaddition of isatins, 2-(aminomethyl)pyridine and isatin-based imines proceeded readily, and furnished novel imidazolidine-dispirooxindoles in up to 84% yield with up to >99 : 1 diastereoselectivity.

A cinchona alkaloid catalyzed enantioselective sulfa-Michael/aldol cascade reaction of isoindigos: construction of chiral bispirooxindole tetrahydrothiophenes with vicinal quaternary spirocenters

Enantioselective sulfa-Michael/aldol reaction of isoindigos has been successfully developed to afford bispirooxindole tetrahydrothiophenes with vicinal quaternary spirocenters.