The regioselective synthesis of spirooxindolo pyrrolidines and pyrrolizidines via three-component reactions of acrylamides and aroylacrylic acids with isatins and α-amino acids

A three-component [3 + 2]-cycloaddition/elimination cascade for the synthesis of spirooxindole-pyrrolizines

A three-component synthesis of novel spirooxindole-tetrahydropyrrolizines from secondary α-aminoacids, isatins and vinyl selenones has been disclosed. Products were formed in good yields and high diastereoselectivity by 1,3-dipolar cycloaddition of in situ generated azomethine ylides followed by spontaneous elimination of benzeneseleninic acid. Good regioselectivities with aryl substituted vinyl selenones were observed. The method showed good functional group tolerance, providing a direct approach to biologically relevant spirooxindoles under mild reaction conditions.

Diversified strategy for the synthesis of DNA-encoded oxindole libraries

DNA-encoded library technology (DELT) employs DNA as a barcode to track the sequence of chemical reactions and enables the design and synthesis of libraries with billions of small molecules through combinatorial expansion. This powerful technology platform has been successfully demonstrated for hit identification and target validation for many types of diseases. As a highly integrated technology platform, DEL is capable of accelerating the translation of synthetic chemistry by using on-DNA compatible reactions or off-DNA scaffold synthesis. Herein, we report the development of a series of novel on-DNA transformations based on oxindole scaffolds for the design and synthesis of diversity-oriented DNA-encoded libraries for screening. Specifically, we have developed 1,3-dipolar cyclizations, cyclopropanations, ring-opening of reactions of aziridines and Claisen–Schmidt condensations to construct diverse oxindole derivatives. The majority of these transformations enable a diversity-oriented synthesis of DNA-encoded oxindole libraries which have been used in the successful hit identification for three protein targets. We have demonstrated that a diversified strategy for DEL synthesis could accelerate the application of synthetic chemistry for drug discovery.

Constructing DNA-encoded oxindole libraries by a diversified strategy.

Ecofriendly synthesis of pyrano[2,3-d]pyrimidine derivatives and related heterocycles with anti-inflammatory activities

A versatile, efficient, clean, and facile method was used for the synthesis of pyrano[2,3-d]pyrimidine derivatives by the one-pot three-component condensation reaction of thiobarbituric acid and malononitrile with p-chlorobenzaldehyde, using Fe₃ O₄ or ZnO or Mn₃ O₄ as nanostructure catalysts. The catalyst could be easily recovered using an external magnet and reused for six cycles with almost a consistent activity. A series of polyheterocyclic compounds containing five and/or six rings fused with each other was designed. The anti-inflammatory activities for some of the newly synthesized compounds were evaluated. All the synthesized compounds were characterized on the basis of their elemental analyses and spectral data.

Synthesis of pyrrolizidines and indolizidines by multicomponent 1,3-dipolar cycloaddition of azomethine ylides

Different multicomponent 1,3-dipolar cycloadditions (1,3-DC) of cyclic α-amino acid derivatives with aldehydes and dipolarophiles have been described as efficient and simple methodologies for the synthesis of the pyrrolidine unit of pyrrolizidines and indolizidines. When free cyclic α-amino acids are used, a thermal promoted decarboxylative process generates in situ the corresponding non-stabilized azomethine ylides, which afforded the corresponding pyrrolizidines and indolizidines with a hydrogen in the bicyclic units. This methodology has been employed to the synthesis of complex systems including spiro derivatives when ketones are used as carbonyl component. In addition, working with cyclic α-amino acid derived esters, the three-component 1,3-DC takes place under milder reaction conditions giving the corresponding pyrrolizidines and indolizidines with an alkoxycarbonyl group in the bridge adjacent carbon to the nitrogen. This methodology can be carried out by a double consecutive or stepwise 1,3-DC to provide pyrrolizidines via the precursor prolinates. The conformation of the azomethine ylide controls the endo/exo diastereoselectivity of the 1,3-DC.

An eco-friendly catalytic system for multicomponent, one-pot synthesis of novel spiro-chromeno indoline-triones and their anti-prostate cancer potentials evaluated via alkaline phosphatase inhibition mechanism

A green and efficient straightforward tactic for the one-pot regioselective synthesis of novel 10,10-dimethyl-9,10,11,11a-tetrahydro-6H-spiro[chromeno[4,3-b]chromene-7,3'-indoline]-2',6,8 (7aH) -triones (4a-n) in one-pot modus has been established using eco-friendly p-toluenesulphonic acid as catalyst. Among the solvents that were used for synthesis, 4a-n were suitably synthesized with maximum yield (90-98%) in water. We avoided column purification and the formed by-product in the process is environmental-friendly. Hence, this reaction may consider as an astonishing piece work in this study, why because, the reaction mechanism that depends on the nature of the group attached to the isatin ring nitrogen atom. The main advantage of this protocol includes short reaction time, good yield, easy to work-up, practical simplicity, high regioselectivity and reduced pollutant, cost and avoids tedious purification. These pharmaceutically important compounds (4a-n) were recognized for their alkaline phosphatase inhibition and prostate cancer medication capabilities. The selective activity relation between alkaline phosphatase and prostate cancer was unveiled through the interaction of 4a-n to Human alkaline phosphatase (PDB ID: 1EW2).

Synthesis of spiropyrrolidine oxindolesviaAg-catalyzed stereo- and regioselective 1,3-dipolar cycloaddition of indole-based azomethine ylides with chalcones

In excess of 100 new compounds were prepared in moderate to high yields (50–95%) with good to excellent diastereoselectivity (11 : 1 → 20 : 1 dr) by Ag-catalyzed 1,3-dipolar cycloaddition.

Synthesis of new spiro pyrrole/pyrrolizine/thiazole derivatives via (3+2) cycloaddition reactions

An efficient one-pot multi-component protocol has been developed for the synthesis of novel spiro-fused pyrrole/pyrrolizine/thiazole derivatives using (3+2) cycloaddition reactions; all products were obtained in moderate to excellent yields and synthesized from commercially available starting materials.

Synthesis, antioxidant and antimicrobial activities of novel thiopyrano[2,3-d]thiazoles based on aroylacrylic acids

Here it is described the synthesis, antioxidant and antimicrobial activity determination of novel rel-([Formula: see text])-6-benzoyl-7-phenyl-2-oxo-3,5,6,7-tetrahydro-2H-thiopyrano[2,3-d]thiazole-5-carboxylic acids. The target compounds were obtained in good yields from 5-arylidene-4-thioxo-2-thiazolidinones and [Formula: see text]-aroylacrylic acids via regio- and diastereoselective hetero-Diels-Alder reaction. The stereochemistry of the cycloaddition was confirmed by NMR spectra. The antioxidant and antimicrobial activity screening identified 7 compounds (3c, 3e, 3f, 3g, 3k, 3l, 3p) with a high level of free radical scavenging (43-77% DPPH assay), and compounds with significant influence on Staphylococcus aureus, Bacillus subtilis and Candida albicans (MIC 3.13-6.25 [Formula: see text]), but slight effect on Escherichia coli.

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.

Divergent Strategy for the Diastereoselective Synthesis of the Tricyclic 6,7-Diaryltetrahydro-6H-benzo[c]chromene Core via Pt(IV)-Catalyzed Cycloaddition of o-Quinone Methides and Olefin Ring-Closing Metathesis

A divergent strategy for the synthesis of the tricyclic 6,7-diaryltetrahydro-6H-benzo[c]chromene core was successfully developed. The 2,3-trans, 2,4-cis trisubstituted chroman moiety was formed via highly efficient and stereoselective Pt(IV)-catalyzed cycloaddition reactions of the corresponding quinone methides with chalcones. Subsequent steps provided the common diene alcohol, which underwent BF₃·Et₂O-mediated Et₃SiH reduction and olefin ring-closing metathesis (RCM) using Ru(II) catalysts. The sequence of the final two steps provided a handle to diversify the stereochemical outcomes at C6 as well as C10a.

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.

Regioselective synthesis of spiroxindolopyrrolidine: a one step cycloaddition reaction twists inherent optical and fluorescence property of ferrocene–anthracene dyad

We report the regioselective synthesis of spiroxindole using a 1,3-dipolar cycloaddition reaction (1,3-DC). Our experiments show that cycloaddition can alter the inherent optical and fluorescence properties of the ferrocene–anthraced dyad system.

Synthesis and Regioselective Reaction of Some Unsymmetrical Heterocyclic Chalcone Derivatives and Spiro Heterocyclic Compounds as Antibacterial Agents

A number of novel heterocyclic chalcone derivatives can be synthesized by thermal and microwave tools. Treatment of 4-(4-Acetylamino- and/or 4-bromo-phenyl)-4-oxobut-2-enoic acids with hydrogen peroxide in alkaline medium were afforded oxirane derivatives 2. Reaction of the epoxide 2 with 2-amino-5-aryl-1,3,4-thiadiazole derivatives yielded chalcone of imidazo[2,1-b]thiadiazole derivative 4 via two thermal routes. In one pot reaction of 4-bromoacetophenone, diethyloxalate, and 2-amino-5-aryl-1,3,4-thiadiazole derivatives in MW irradiation (W 250 and T 150 °C) under eco-friendly conditions afforded an unsuitable yield of the desired chalcone 4d. The chalcone derivatives 4 were used as a key starting material to synthesize some new spiroheterocyclic compounds via Michael and aza-Michael adducts. The chalcone 4f was similar to the aryl-oxo-vinylamide derivatives for the inhibition of tyrosine kinase and cancer cell growth. The electron-withdrawing substituents, such as halogens, and 2-amino-1,3,4-thiadiazole moeity decreasing the electron density, thereby decreasing the energy of HOMO, and the presence of imidazothiadiazole moiety should improve the antibacterial activity. Thus, the newly synthesized compounds were evaluated for their anti-bacterial activity against (ATCC 25923), (ATCC 10987), (ATCC 274,) and (SM514). The structure of the newly synthesized compounds was confirmed by elemental analysis and spectroscopic data.

Potent Synergy between Spirocyclic Pyrrolidinoindolinones and Fluconazole against Candida albicans

A spiroindolinone, (1S,3R,3aR,6aS)-1-benzyl-6'-chloro-5-(4-fluorophenyl)-7'-methylspiro[1,2,3a,6a-tetrahydropyrrolo[3,4-c]pyrrole-3,3'-1H-indole]-2',4,6-trione, was previously reported to enhance the antifungal effect of fluconazole against Candida albicans. A diastereomer of this compound was synthesized, along with various analogues. Many of the compounds were shown to enhance the antifungal effect of fluconazole against C. albicans, some with exquisite potency. One spirocyclic piperazine derivative, which we have named synazo-1, was found to enhance the effect of fluconazole with an EC50 value of 300 pM against a susceptible strain of C. albicans and going as low as 2 nM against some resistant strains. Synazo-1 exhibits true synergy with fluconazole, with an FIC index below 0.5 in the strains tested. Synazo-1 exhibited low toxicity in mammalian cells relative to the concentrations required for antifungal synergy.

Molecular diversity of spirooxindoles. Synthesis and biological activity

Spirooxindoles are important synthetic targets possessing extended biological activity and drug discovery applications. This review focuses on the various strategies for the enantioselective synthesis of spirocyclic oxindoles relying on reports over the past decade and from earlier work. The spirooxindoles in this review are separated into three structural classes, and then further categorized into the method type from which the spirocycle is generated.