| 93% |
With SO3H and COOH functionalized pine-cone derived carbon nanoparticles In lithium hydroxide monohydrate at 25℃; for 0.133333h; Green chemistry; |
3.5. General Procedure for the Synthesis of 5-arylidene-2,4-thiazolidinedione Derivatives (4a-j)
General procedure: Knovenagel condensation of aromatic aldehyde (1mmol) and 2,4-thiazolidinedione (1 mmol) was performedin the presence of Pine -SO3H NPs (0.05 g) and water (5mL) as a solvent. The mixture was stirred at room temperature.Upon completion of the reaction, monitored by TLC(ethyl acetate: n-hexane 3:7), the mixture filtered off. Theproducts were purified by recrystallization from EtOH. |
| 92% |
With Ce1Mg0.6Zr0.4O2 In ethanol; lithium hydroxide monohydrate at 75℃; for 1.5h; |
|
| 92% |
With propylamino functionalized nano-structured SBA-15 In ethanol at 50℃; for 2h; |
General Procedure for the Preparation of 2,4-Thiazolidinediones (3h-3n)
General procedure: A mixture of the aromatic aldehyde (1 mmol), 2,4-thiazolidinedione (0.133, 1 mmol) [orrhoda-nine (0.117 g, 1 mmol)] and SBA-15-Pr-NH2 (0.05 g) in EtOH (5 mL) was stirredat 50C in an oil bath for 2 hours; the progress of the reaction was monitored by TLC(2:1 n-hexane/ethyl acetate). After completion of the reaction, 10 mL acetone was addedand the mixture was filtered to remove the catalyst. Upon addition of 5 mL H2O to the filtrate,the precipitated solid obtained was collected and recrystallized from ethanol to givethe pure products, characterized by comparison of their 1H NMR spectra and meltingpoints with those reported in the literature. |
| 92% |
With titanium silicate (TS-1) In lithium hydroxide monohydrate at 90℃; |
General reaction procedure 5-arylidene-2,4-thiazolidinediones
General procedure: The condensation of 2,4-thiazolidinedione/rhodaninediones (1 mmol), with arylaldehydes (1 mmol), in the presence of a catalytic amount of TS-1 (0.04 g) in aqueous medium at 90 C was carried out by refluxing the reaction mixture for30-60 min to obtain 5-arylidene-2,4-thiazolidinediones/Rhodaninediones derivatives, as shown in Table 2, which afforded the corresponding products in excellent yields up to 92% within 30 min. Active methylene thiazolidinedione was preparedby using a reported method [41]. The progress of the reaction was monitored by thinlayer chromatography using PET ether: ethyl acetate (8:2) as a solvent system. After completion of the reaction, the reaction mixture was filtered to recover the catalystTS-1. The filtrate was concentrated to obtain crude product, which was recrystalized from hot ethanol to obtain pure product (2a-i). |
| 91% |
With 1,1'-(propane-1,3-diyl)bis(3-methyl-1H-imidazol-3-ium) dibromide at 80℃; for 2h; Ionic liquid; |
|
| 90% |
With tetra(n-butyl)ammonium hydroxide In ethanol; lithium hydroxide monohydrate at 50℃; for 1.5h; Green chemistry; |
General procedure for the preparation of 5-aryilidene-2,4-thiazolidinediones and 5-benzylidene rhodanines
General procedure: A mixture of aromatic aldehyde (1 mmol), 2,4-thiazolidinedione or rhodanine (1 mmol) and TBAH (1 mL, 50%) were mixed in EtOH-H2O (1:1, 3 mL). The reaction mixture was stirred at 50°C in an oil bath for 1.5 h. The progress of reaction was monitored on TLC. After completion of reaction, the resulting precipitate was filtered and washed with ethanol to afford the pure product as solid in good to excellent yields. The known products were characterized by comparing the 1H NMR and melting point data with those reported in the literature. |
| 89% |
With methylamine In glacial acetic acid |
|
| 82% |
With 1-[2-(2-hydroxyethoxy)ethyl]-1,5-diazabicyclo[4.3.0]non-5-ene chloride In neat (no solvent) at 80℃; for 0.333333h; Green chemistry; |
General procedure for Knoevenagel condensation
General procedure: A round bottom flask was charged with aryl aldehyde (10 mmol), 2,4-thiazolidinedione (10 mmol) and ionic liquid (2 mmol). The reaction mixture was stirred and monitored by TLC. Upon completion, water was added and the mixture was stirred. The mixture was allowed to stand to separate into two layers, affording the product and ionic liquid. The separated solid product was suction-filtered and further purified by crystallization from hot EtOH. The filtrate containing the ionic liquid was then evaporated under reduced pressure, and the ionic liquid was reused directly for the next run. The melting point and spectra data of products are given as below. |
| 80% |
With lithium bromide for 0.133333h; Microwave irradiation; neat (no solvent); |
|
| 75% |
With urea In neat (no solvent) for 2h; |
Optimization of the reaction conditions for the synthesis of5-arylidene-thiazolidine-2,4-dione derivatives
General procedure: To a 25 mL flask, 50 mg of the catalyst, 1 mmol of TZDand 1 mmol of aldehyde were added. The reaction mixturewas maintained under constant agitation for 2 h at 80 C. |
| 68% |
With piperidine In ethanol Reflux; |
Synthesis of 5-benzylidine 2, 4-thiazolidinedione (II)
General procedure: Equimolar mixture of substituted benzaldehyde (20 mM)and 2,4-thiazolidinedione (20 mM) with catalytic amount ofpiperidine (1.4 g, 16 mM) and ethanol (150 mL) was refluxedcontinuously for 30-35 hours. The reaction mixturewas poured into water and filtered. On cooling, the productwas precipitated out from ethanol [36]. This step was used tosynthesize a total of ten intermediates (FP1I-FP10I). |
| 67% |
With anhydrous Sodium acetate In glacial acetic acid for 0.0833333h; Microwave irradiation; |
|
| 62% |
With piperidine; glacial acetic acid In toluene for 14h; Heating; |
General procedure for synthesis of (E)-5-substitutidenethiazolidine-2,4-dione) (A1-A10)
General procedure: The substituted aldehydes (0.01 mol), thiazolidine-2,4-dione (0.01 mol), piperidine (0.01 mol), and acetic acid (0.01mol) were dissolved in toluene (25 ml) and heated up to Rffor azeotropic removal of water around 14 h. The mixturewas cool up to 5°C, precipitates obtained filter it, washedwith distilled water and recrystallized from appropriatesolvents to obtain pure products (A1-A10). Physical data ofthe compounds (A1-A10) are given in Table 1. |
| 47% |
With 1-benzyl-4,5-dimethylimidazole 3-oxide In acetonitrile for 12h; Heating; |
|
|
With anhydrous Sodium acetate; glacial acetic acid |
|
|
With anhydrous Sodium acetate In glacial acetic acid |
|
|
With pyridine In ethanol for 5.5h; Reflux; |
|
|
With piperidine In toluene for 3h; Reflux; |
|
|
With morpholine In benzene |
|
|
|
2. Experimental
General procedure: 5-Arylidene-2,4-thiazolidinediones were synthesized by Knoevenagel condensation of 2,4-thiazolidinedione (TZD) with appropriate aryl aldehydes [20]. |
|
With piperidine In toluene |
|
|
With piperidine In ethanol Reflux; |
|
|
With anhydrous Sodium acetate; glacial acetic acid |
|
|
With piperidine at 120℃; |
General procedure for the synthesis of 5-(4-methylbenzylidene)-3-((1-(4-tolyl)-1H-1,2,3-triazol-4-yl)methyl)thiazolidine-2,4-dione (5a):
General procedure: A mixture of thiazolidine-2,4-dione (1.0 equiv.), 4-methylbenzaldehyde (1.0 equiv.), piperidine (1.0 equiv.) and 5 mL of PEG-400 was placed in a 50 mL round-bottomed flask and the contents were stirred magnetically in an oil-bath maintained at 120 °C until 5-(4-methylbenzylidene)thiazolidine-2,4-dione (3) was formed (3-4 h), which was monitored by TLC using ethyl acetate-petroleum ether, (30:70, v/v) as eluent. |
|
With anhydrous Sodium acetate; glacial acetic acid Reflux; |
|
|
With 1-n-butyl-3-methylimidazolium tetrafluoroborate at 20℃; for 7h; Green chemistry; |
|
|
With piperidine In ethanol Reflux; |
|
|
With anhydrous Sodium acetate; glacial acetic acid at 110℃; for 5h; |
|
|
With piperidine In ethanol for 24h; Reflux; |
3.2. General Procedure for the Synthesis of 2,4-Dioxothiazolidine Acid Derivatives
General procedure: 2,4-Dioxothiazolidine acid derivatives were prepared in three steps following the reportedmethod [35,40]. A solution of previously prepared TZD 1 was treated with various appropriatealdehydes via refluxing in ethanol for 24 h in the presence of piperidine as a catalyst. The reactionmixture was poured into water, followed by acidification with acetic acid to aord compounds 2a-g.Then a mixture of 2a-g (1 mmol) and ethyl 2-bromoacetate (2 mmol) was refluxed for 24 h in acetonein the presence of potassium carbonate (2 mmol) to furnish the target product as a white solid afterevaporation of the solvent. The crude product was used directly in the next step for the preparation ofthe free carboxylic acid derivatives 3a-g, where the solid product was refluxed with glacial acetic acidand HCl at a ratio of 4:1 for 2 h to aord the pure (2,4-dioxothiazolidine-3-yl)-acetic acid derivatives3a-g after evaporation of the solvents and crystallization with ethanol. The spectral data for 3a,3f, and 3g are in good agreement with previously reported ones [7,13,15] and other spectra in theSupplementary Materials. |
|
With piperidine In ethanol for 24h; Reflux; |
|
|
With piperidine In toluene at 110℃; |
Synthesis of 5-substituted-2,4-thiazolidinedione(5a-j)
General procedure: Substituted benzaldehyde (0.1 mol) [3a-j] was added to 2,4-thiazolidinedione (0.1 mol) in toluene in the presence of piperidine and refluxed at 110 C for 6-7 h and then cooled to room temperature to precipitate out the corresponding TZD derivatives (5a-j). TLC (ethylacetate: n-hexane, 6:4)was used for verifying the improvement of the process. |
|
With sodium hydroxide In ethanol; lithium hydroxide monohydrate |
|
|
With anhydrous Sodium acetate; glacial acetic acid |
|
|
With piperidine In ethanol for 10h; Reflux; |
|
|
With anhydrous Sodium acetate; glacial acetic acid for 3h; Reflux; |
|
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