Abstract:The catalytic ability of ZrO 2 /SO 4 2-to promote solventless three-component condensation reactions of a diversity of aromatic aldehydes, urea or thoiurea and ethyl acetoacetate was studied. Products resulting from Hantzsch and/or Biginelli multicomponent reactions are obtained in the presence of solid acid catalysts using the same reactants but different temperature conditions. The sulfated zirconia catalyst can be recovered and recycled in subsequent reactions with a gradual decrease of activity.
Sulfated zirconia and SZ/MCM-41 were used as catalysts for the synthesis of β-aminoalcohols via epoxide aminolysis. Sulfated zirconia was prepared by sol-gel and SZ/MCM-41 was obtained by impregnation. Solid catalysts were characterized by XRD, SEM-EDS, UV-Vis, FT-IR pyridine desorption and Nitrogen physisorption. Both acid materials were useful as catalysts, even when they were recycled several times. The β-aminoalcohols were characterized by FT-IR, 1 H-and 13 C-NMR and GC-MS.
Experimental details for compounds 1a-f, 2a-f, 3a-f and 4a-f.
General methodsCommercially available reagents and solvents were used as received. Alkynes I, 12 II, 13 III 23 and IV 22 were synthesized as reported in the literature. Compound 3a has been reported elsewhere 5 and its spectroscopic characterization is consistent with the one described in this article. Flash column chromatography was performed on Kieselgel silica gel 60 (230-400 mesh). Melting points were determined on a Fisher-Johns apparatus and are uncorrected. IR spectra were recorded on a Bruker Alpha FT-IR/ATR spectrometer. NMR spectra were obtained with a JEOL ECA-500 (500 MHz) spectrometer. Chemical shifts (δ) are given in ppm downfield from Me 4 Si as an internal reference; coupling constants are given in Hertz.High-resolution mass spectra (HRMS) were recorded on a JEOL JMS-SX 102a and Agilent-MSD-TOF-1069A spectrometers 41.
Typical procedure for the synthesis of 1,2,3-triazoles derived from methylaniline(1-Benzyl-1H-1,2,3-triazole-4-ylmethyl)-methyl-phenyl-amine (1a). To a 20 mL roundbottomed flask equipped with a magnetic stirrer, were charged 11 mg (0.053 mmol, 5 mol%) of Cu(OAc) 2 •H 2 O, 10 mg (0.053 mmol, 5 mol%) of 1,10-phenanthroline monohydrate, and 204 mg (1.03 mmol) of sodium L-ascorbate. After addition of 7 mL of a mixture EtOH-H 2 O (4:1 v/v), the resulting suspension was stirred for five minutes at room temperature. Subsequently, 150 mg (1.03 mmol) of (I), 81 mg (1.24 mmol) of sodium azide, and 0.14 mL (1.24 mmol) of benzyl chloride were added to the reaction mixture, which was stirred during 18 h at room temperature. 5 mL of H 2 O were added to the reaction mixture and the precipitate was filtered off, washed thoroughly with H 2 O, petroleum ether, and dried under vacuum. The crude product was purified by column chromatography
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