Anshu Dandia

Step-economic, efficient, ZnS nanoparticle-catalyzed synthesis of spirooxindole derivatives in aqueous medium viaKnoevenagel condensation followed by Michael addition

An environmentally friendly, one-pot, three-component ZnS nanoparticle-mediated synthesis of biologically important spirooxindole derivatives in water under ultrasonic irradiation is described herein. ZnS nanoparticles were synthesized by aqueous chemical method. The advantages of this method lies in its simplicity, cost effectiveness, environment friendliness, easier scaling up for large scale synthesis without using high pressure, temperature and toxic chemicals. Greenness of the process was well instituted as water was exploited both as reaction media as well as medium for synthesis of catalyst (ZnS nanoparticles). The particle size was determined by transmission electron microscopy (TEM) and XRD. Compared with other methods for synthesis of spirooxindole derivatives, satisfactory results were obtained with high yields, short reaction time, with simple experimental procedure. After reaction course, the ZnS NPs can be recycled and reused without any apparent loss of activity.

Versatile three component procedure for combinatorial synthesis of biologically relevant scaffold spiro[indole-thiazolidinones] under aqueous conditions

A straightforward aqueous-mediated ultrasound-promoted novel protocol is developed for the quantitative synthesis of medicinally important spiro[indole-thiazolidinone] libraries by the tandem reaction of readily available reagents using cetyltrimethylammonium bromide as a phase transfer catalyst. The present method is more convenient and efficient as compared to multistep conventional processes and it obviates the azeotropical removal of water and use of carcinogenic solvents and dehydrating agents. Other features of this method are operational simplicity and increased safety for high speed synthesis and minimal environment impact.

CuFe2O4 nanoparticles as a highly efficient and magnetically recoverable catalyst for the synthesis of medicinally privileged spiropyrimidine scaffolds

A highly efficient and green protocol for the synthesis of medicinally important fluorinated spiropyrimidine derivatives involving creation of six new covalent bonds has been developed using a magnetically separable and reusable heterogeneous copper ferrite nanocatalyst under mild reaction conditions. The synthesis of inverse spinel copper ferrite magnetic nanoparticles with average size of 38 nm has been achieved using combined sonochemical and co-precipitation techniques in aqueous medium from readily available inexpensive starting materials without any surfactant or capping agent. The particle size was determined by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The magnetic nature of catalyst facilitates its easy removal from the reaction medium and can be reused five times without any significant loss of its catalytic activity. Negligible leaching of Cu and Fe in consecutive cycles makes the catalyst economical and environmentally benign. The structure of final products was established by single crystal X-ray analysis and spectroscopic techniques.

NaCl as a Novel and Green Catalyst for the Synthesis of Biodynamic Spiro Heterocycles in Water Under Sonication

Abstract An efficient and novel green catalytic protocol for the synthesis of biologically important spirooxindole derivatives is developed in a one-pot, three-component approach involving substituted isatin, activated methylene reagent, and 3-methyl-1-phenyl-2-pyrazolin-5-one in water under sonication. This report describes the use of sodium chloride as a nonacidic and green catalyst for a variety of substrates. The advantageous features of this methodology are the environmentally benign character, operational simplicity, high yield processing, easy handling, and the fact that the products do not need to be purified.

Microwave Assisted Synthesis of Fluorinated Hexahydro 1,3,5‐Triazine Derivatives in Aqueous Medium and One Pot Synthesis of 1,2,4‐Triazolo(4,3‐a)1,3,5‐triazines

Abstract A multi‐component condensation of substituted phenylthiourea/urea, aqueous formaldehyde and substituted aromatic/heterocyclic amines lead to 2‐thioxohexahydro‐1,3,5‐triazines (4) in aqueous medium under microwave irradiation in 30–60 sec in quantitative yield with reasonable purity. Further, triazolo[4,3‐a]triazines were also prepared by a one‐pot reaction of ‘in situ’ synthesized triazinyl hydrazine (7) with CS2 (9).

Dry-media one-pot syntheses of fluorinated-2,3-dihydro-1,5-benzothiazepines under microwave activation

A new efficient and environmentally friendly green chemistry procedure for the syntheses of a series of 8-substituted-2-carboxy-2,3-dihydro-1,5-benzothiazepines under microwave irradiation and solvent-free conditions is described. Results were compared with those obtained following classical thermal method. A judicious choice of the reaction conditions allowed the final products 4a–f to be generated in excellent yields in a one-step procedure, whereas experiments under thermal conditions led to benzothiazepines along with other products in lower yields with tedious work-up.

MICROWAVE INDUCED DRY-MEDIA SYNTHESIS OF SPIRO[INDOLE-THIAZOLIDINONES/ THIAZINONES] AS POTENTIAL ANTIFUNGAL AND ANTITUBERCULAR AGENTS AND STUDY OF THEIR REACTIONS

A series of new spiro[3H-indole-3,2′-thiazolidine]-2,4′(1H)-diones (IV) and spiro[3H-indole-3,2′-tetrahydro-1,3-thiazine]-2,4′(1H)-diones (V) have been synthesized in 85–93% yield by the one-pot environmentally benign microwave induced technique involving the cyclocondensation of 3-arylimino-2H-indol-2-ones (III) with thioacids viz. mercapto aceticacid (a)/3-mercapto propionicacid (b) using montmorillonite KSF as inorganic solid support. Intermediates (III) were synthesized in situ by the reaction of indole-2,3-diones (I) and substituted anilines (II). The spiro compounds have been further subjected to solvent-free acetylation, aminoalkylation and thiation under microwave irradiation using solid supports. The synthesized compounds have been screened in vitro for antifungal activity against Rhizoctonia solani, Fusarium oxysporum, and Collectotrichum capsici, and antitubercular acivity against Mycobacterium tuberculosis.

Synthesis of fluorinated ethyl 4-aryl-6-methyl-1,2,3,4-tetrahydropyrimidin-2-one/thione-5-carboxylates under microwave irradiation

Abstract Microwaves have been found to greatly accelerate the Biginelli synthesis of fluorine containing ethyl 4-aryl-6-methyl-1,2,3,4-tetrahydropyrimidin-2-one/thione-5-carboxylates in unsealed vessels using ethanol as energy transfer medium. Results were compared with those obtained following the classical method. The advantages obtained by the use of microwave irradiation were demonstrated. All synthesized compounds have been characterized on the basis of elemental analyses, IR, 1 H NMR and 19 F NMR spectral studies.

An Efficient Procedure for the Synthesis of Spiro (3H-Indole-3,4′ (1′H)pyrano[2,3-C]pyrrole]-5′-carbonitriles Using Solid Inorganic Supports and Microwave Activation

Abstract Microwave irradiation accelerates the Michael condensation of 3-dicyanomethylene-2H-indole-2-one with 2-pyrrolidone/ N-methy1-2-pyrrolidone (i) adsorbed on neutral alumina in “dry media” (ii) using absolute ethanol as energy transfer medium. 3-Dicyanoniethylene-2H-indol-2-one was synthesized under microwave irradiation using indole-2,3-dione and malononitrile. The results were compared with those obtained following the classical method. The advantages obtained by the use of microwave irradiation are demonstrated.

Synthesis, 19F NMR spectral studies and antibacterial evaluation of some new fluorine containing indole derivatives

Abstract The condensation behaviour of various fluorine containing 3-indolylimino derivatives with mercaptoacetic acid and with chloroacetyl chloride has been studied. The cyclocondensation of 3-arylimino-2H-indol-2-ones(III; Ar = 4FC6H4, 3CF3C6H4, 2Cl3CF3C6H3, 2,3,4,5-tetra-FC6H and 2,3,4,6-tetra-FC6H) with mercaptoacetic acid yielded 3′-phenylspiro [3H-indole-3,2′-thiazolidine]-2,4′(1H)-diones (IV) in 75–90% yields. Reaction of anil (III; Ar = 2,3,4,5-tetra-FC6H) with chloroacetyl chloride gave spiro[azetidine-2,3′- 3H indole]-2′, 4(1′H)-dione (VI) in 75% yield. However, similar reactions in the case of 3-(pentafluorophenylimino)-2H-indol-2-one did not give the expected spiro compounds: 3-indolylmercaptoacetic acid (V) was obtained with mercaptoacetic acid, while the product from chloroacetyl chloride could not be characterized. Further, the reactions of various fluorine containing isatin-3-hydrazones (VII; Ar = 4C6H4, C6F5, 1,2,4-triazino [5,6-b] indole, benzimidazole) with mercaptoacetic acid also did not give corresponding spiro compounds and unchanged compounds (VII) were recovered. The compounds synthesized have been characterized by their analytical and spectral (IR, 1H NMR & 19F NMR) data, and were screened for antibacterial activity.