95% |
With 1-n-butyl-3-methylimidazolium azide; In water; at 60℃; for 0.5h;Green chemistry;Catalytic behavior; |
Fe3O4WO3-EAE-SO3H (III) (0.01 g) was added to a solutionof aniline (0.093 g, 1.0 mmol), triethyl orthoformate (0.177 g,1.2 mmol) and 1-butyl-3-methylimidazolium azide (0.216 g,1.2 mmol) in water (5 mL). The reaction mixture was allowedto stir magnetically at 60 C for 30 min. After completion ofthe reaction (as monitored by TLC), the reaction mixture wascooled to room temperature and the catalyst was separated withan external magnet. Then the resulting solution was extracted with EtOAc (3 15 mL). The organic layer was washedwith brine, dried over anhydrous Na2SO4 and evaporated underreduced pressure. The crude product was recrystallized fromethylacetate/n-hexane (1/9 v/v) to afford the pure 1-phenyl-1H-tetrazole (1.48 g, 95%). The recovered catalyst was washedwith hot ethyl acetate, dried at 60 C for 2 h and reused forsubsequent cycles. |
93% |
With sodium azide; In neat (no solvent); at 100℃; for 0.75h;Catalytic behavior; |
General procedure: A mixture of amine (1 mmol), sodium azide (1 mmol), triethyl ortho-formate (1.2 mmol) and catalyst (0.01 g, 0.4 mol% of Cu(II)) was taken in a round-bottomed flask and stirred at 100 C. The progress of the reaction was followed by thin-layer chromatography (TLC). After completion of the reaction, the reaction mixture was cooled to room temperature and diluted with ethyl acetate (2 × 20 mL). The catalyst was removed by using magnetic field and then the resulting solution was washed with water, dried over anhydrous Na2SO4 and was evaporated. The residue was concentrated and recrystallized from EtOAc-hexane (1:10). |
92% |
With sodium azide; In neat (no solvent); at 100℃; for 1.25h; |
General procedure: A mixture of amine (1mmol), sodium azide (1.2 mmol), triethyl orthoformate (1.2 mmol) and catalyst (0.02 g, contains 0.4 mol% of Cu(II)) was taken in a round-bottomed flask and stirred at 100 C. The progress of the reaction was followed by thin-layer chromatography (TLC). After completion of the reaction, the reaction mixture was cooled to room temperature and diluted with ethyl acetate (3×20 mL). The catalyst was removed by using magnetic field or filtration and then the resulting solution was washed with water, dried over anhydrous Na2SO4 and was evaporated. The residue was concentrated and recrystallized from EtOAc-hexane (1:9). All products were characterized by 1H, 13C NMR, FT-IR, and melting point which were in agreement with literature. We have reported the spectral data of some aromatic and heteroaromatic synthesized compounds. |
92% |
With sodium azide; zinc sulfide; In N,N-dimethyl-formamide; at 20℃; for 0.333333h;Sonication; |
General procedure: A mixture of selected primary amine (1mmol), triethyl orthoformate (1.2mmol) and sodium azide (1mmol) in the presence of 0.01g ZnS nanoparticles was added to N,N-dimethylformamide as solvent and the reaction mixture was irradiated in ultrasonic apparatus with the power 50W. The progress of the reaction was monitored by thin layer chromatography (TLC). After completion of the reaction, the mixture was diluted by 1:1 H2O:ethylacetate (10ml), stirred at ambient temperature (20min) and centrifuged to separate the solid catalyst. The organic layer of the solution was separated, dried over sodium sulfate, and the organic solvent and other residues were stripped in a vacuum evaporator. The product was purified by recrystallization in a mixture of EtOAc:MeOH (3:1) to yield pure product. The obtained pure tetrazoles were characterized by spectroscopic data and melting points. |
92% |
With sodium azide; bis(trifluoromethanesulfonyl)amide; In glycerol; at 20℃; for 3.0h;Green chemistry;Catalytic behavior; |
General procedure: A mixture of amine (2 mmol), sodium azide (2 mmol), triethylorthoformate (2.4 mmol), glycerol (8 mL) and HNTf2 (5 mol%) wastaken in a round bottomed flask and stirred at room temperature. Theprogress of the reaction was monitored by TLC. After completion, thereaction mixture was diluted with cold water (5 mL) and extracted witha mixture of hexane/ethyl acetate 95:5 (3 × 10 mL). The combinedorganic layers were washed with brine and dried over anhydrousNa2SO4. The residue was concentrated and recrystallised from ethylacetate/hexane 2:1 to afford the pure product. |
90% |
With sodium azide; cobalt ferrite; In neat (no solvent); at 120℃; for 2.0h;Green chemistry; |
General procedure: CoFe2O4 magnetic nanocatalyst (20 mol%) was added toa mixture of amine (2 mmol), NaN3 (2 mmol), triethyl orthoformate(2.4 mmol) and stirred at 120 oC for 2 h (Table 1). After completion of the reaction, the catalyst was separated from the reaction mixture with an external magnet and the reaction mixture was diluted with cold water (5 mL) and extracted with ethyl acetate (10 mL 3). The combined organic layers were washed with brine and dried over anhydrous Na2SO4. After concentration, a crystallization step was performed using EtOAc-petroleum ether to afford the pure product. All of the desired product(s) were characterized by comparison of their physical data with those of known compounds[6,7,17]. |
90% |
With sodium azide; In neat (no solvent); at 100℃; for 1.33333h; |
A mixture of 2 mmol of aromatic amine 1a-1j, 0.13 g (2 mmol) of sodium azide, 0.296 g (2 mmol) of triethyl orthoformate, and 50 mg of the copper nanocatalyst was stirred at 100 C until no further progress in the conversion was observed according to the TLC data. The mixture was allowed to cool down to room temperature, the catalyst was separated by strong magnet, the mixture was poured onto ice, and the organic layer was extracted with ethyl acetate (2 × 20 mL). The combined extracts were dried over anhydrous MgSO4, filtered, and evaporated, and the residue was recrystallized from ethyl acetate-hexane (1 : 10). The yields and melting points of tetrazoles 2a-2j are given in Table 4. 1-Phenyl-1H-tetrazole (2a). IR spectrum (KBr), nu, cm-1: 3051, 2925, 2854, 1678, 1660, 1585, 1487, 1448, 1316, 1279, 1227, 1209, 1171, 1153, 1076, 986, 899, 806, 765, 754, 694, 619, 593. 1H NMR spectrum (90 MHz, CDCl3), delta, ppm: 8.27 s (1H), 6.98-7.60 m (5H). |
89% |
With sodium azide; In neat (no solvent); at 120℃; for 4.0h;Green chemistry;Catalytic behavior; |
General procedure: HClO4-SiO2 (0.08 g) was added to a mixture of amine (2 mmol), NaN3 (2 mmol), triethyl orthoformate (2.4 mmol) and stirred at 120 C for the appropriate time (Table 1). After completion (as monitored by TLC), the reaction mixture was diluted with cold water (5 mL) and extracted with ethyl acetate (10 mL ? 3). The catalyst was removed by filtration. The combined organic layers were washed with brine and dried over anhydrous Na2SO4. After concentration, a crystallizaton step was performed using EtOAc-hexane to afford the pure product. The physical data (mp, IR, NMR) of known compounds were found to be identical with those reported in the literature [9,10,11,12a,15]. |
|
With sodium azide; acetic acid; at 80℃; for 4.0h;Green chemistry; |
Aniline (10 mmol, 930 mg), sodium azide (11 mmol, 715 mg), triethyl orthoformate (30 mmol, 4440 mg) and glacial acetic acid (80 mmol, 4800 mg) were added to a 100 mL reaction flask.The mixture was stirred in an oil bath at 80 C for 4 hours, cooled to room temperature, diluted with saturated brine (100 mL) and finally sodium carbonate was added until the evolution of the gas was stopped, filtered, washed with water and dried in vacuo at 50 C to give phenyl- 1H-tetrazole. |
|
With sodium azide; acetic acid; at 80℃; for 24.0h; |
General procedure: The mono1-aryl-1H-tetrazoles 1a-f were synthesized by the literature method.[35,36] The1-substituted-aryl-amine (10 mmol) was treated with sodium azide (10 mmol), triethylorthoformate (10 mmol) in 100mL of acetic acid. It was refluxed for 24 h at 80 C. Thereaction progress was checked by TLC. Once the reaction was completed, the reactionmixture was transferred into a beaker containing ice. The solid product was separatedon cooling, filtered and dried. The equimolar mixture of 1-substituted-aryl-tetrazole(5 mmol) 1a-f is treated with ethyl-2-chloro-2-oxoacetate (5 mmol) in the presence of acatalytic amount of DIPEA in THF (100 mL) (Scheme 1). It was refluxed for 16 h. Theprocess of the reaction was checked by TLC. After the formation of a product, the reactionmixture was poured into ice. The solid product was separated, filtered and dried.The compound was purified by column chromatography using the pet ether and benzenein the ratio 7:3. The yield of the product was 88-95%. Then, the title compound(0.5 g) was synthesized by hydrolysis of compounds 3a-f in the presence ofConcentrated HCl (1 mL) and 10mL of ethanol (Scheme 1). The reaction was refluxedfor 6 h. The formation of the product was confirmed with the help of TLC and the reactionwas quenched by pouring the mixture into ice. The solid product was filtered offand dried. The products 4a-f were obtained in good yield of 90%. |