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Synlett 2007(14): 2301-2303  
DOI: 10.1055/s-2007-984921
LETTER
© Georg Thieme Verlag Stuttgart · New York

Silica-Immobilized CuI: An Efficient Reusable Catalyst for Three-Component Coupling Reaction of Aldehyde, Amine and Alkyne

Pravin R. Likhar*a, Sarabindu Roya, Moumita Roya, M. S. Subhasa, M. Lakshmi Kantama, Rajib Lal Deb
a Inorganic & Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad 500007, India
b Department of Chemistry, Jadavpur University, Kolkata 700032, India
Fax: +91(40)27160921; e-Mail: plikhar@iict.res.in;
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Publikationsverlauf

Received 11 April 2007
Publikationsdatum:
24. Juli 2007 (online)

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Abstract

Silica-supported copper catalysts were effectively used in the three-component coupling of aldehydes, amines and alkynes to afford the corresponding propargylamines in moderate to ex­cellent yields. The catalyst was quantitatively recovered from the reaction by a simple filtration and reused for a number of cycles with almost consistent activity.

Key words

silica - copper - three-component coupling - propargyl­amines - reusable catalyst

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Preparation of Imine-Modified Silica-Supported Copper Catalysts:17
SiO 2 -Py-Cu(OAc) 2 : SiO2-Py (1 g) was stirred with a solution of Cu(OAc)2 (1 mmol) in acetone (25 mL) for 24 h to get SiO2-Py-(CuOAc)2. The copper content was measured by ICP-AES and it was found to be 0.43 mmol/g. Similarly SiO2-Sal-Cu(OAc)2 (Cu: 0.41 mmol/g), SiO2-BPy-Cu(OAc)2 (Cu: 0.39 mmol/g), and SiO2-Thio-Cu(OAc)2 (Cu: 0.41 mmol/g) were prepared from Cu(OAc)2 in acetone. SiO2-Py-CuCl2 (Cu: 0.47 mmol/g) was prepared from an acetone solution of CuCl2. SiO2-Py-CuI was prepared from a MeCN solution of CuI and the copper content was 0.45 mmol/g.

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Typical Procedure for A ³ Coupling Reaction: A mixture of aldehyde (1 mmol), amine (1.2 mmol), alkyne (1.5 mmol) and SiO2-Py-CuI (110 mg, 5 mol%) in MeCN (3 mL) was stirred in a round-bottomed flask at 90 °C under nitrogen. After completion of the reaction (monitored by TLC) the catalyst was filtered. After removing the solvent at reduced pressure, the crude material was purified by chromatography on silica gel using hexane-EtOAc mixture as eluent to afford the corresponding propargylamines. Spectroscopic data of the new compounds are given below:
Diallyl-[1-(4-bromophenyl)-3-phenylprop-2-ynyl]amine (Table 3, entry 12): 1H NMR (300 MHz, CDCl3): δ = 7.40-7.62 (m, 6 H), 7.28-7.38 (m, 3 H), 5.70-5.91 (m, 2 H), 5.24 (d, J = 17.0 Hz, 2 H), 5.12 (d, J = 9.3 Hz, 2 H), 4.99 (s, 1 H), 3.16-3.29 (m, 2 H), 2.90-3.06 (m, 2 H). 13C NMR (75 MHz, CDCl3): δ = 138.5, 136.3, 131.8, 131.1, 129.8, 128.4, 122.8, 121.4, 117.4, 88.1, 84.7, 55.9, 53.5. ESI-MS: m/z = 368 [M + 1], 366 [M + 1], 271, 269, 146, 104. Anal. Calcd for C19H20BrN: C, 66.67; H, 5.89; N, 4.09. Found: C, 66.71; H, 5.92; N, 4.01.
4-[1-(4-Bromophenyl)-3- p -tolylprop-2-ynyl]morpholine (Table 3, entry 16): 1H NMR (300 MHz, CDCl3): δ = 7.45-7.61 (m, 4 H), 7.37 (d, J = 8.0 Hz, 2 H), 7.12 (d, J = 8.0 Hz, 2 H), 4.69 (s, 1 H), 3.61-3.79 (m, 4 H), 2.52-2.68 (m, 4 H), 2.38 (s, 3 H). 13C NMR (75 MHz, CDCl3): δ = 138.5, 137.1, 131.8, 131.3, 130.3, 129.0, 121.7, 119.8, 89.1, 83.5, 67.2, 61.4, 49.8, 21.4. EI-MS: m/z = 371 [M+], 369 [M+], 285, 283, 214, 205, 189, 128, 86, 56. Anal. Calcd for C20H20BrNO: C, 64.87; H, 5.44; N, 3.78. Found: C, 64.89; H, 5.47; N, 3.75.