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Synlett 2009(11): 1791-1794  
DOI: 10.1055/s-0029-1217362
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Propargylamines by Three-Component Coupling of Aldehydes, Amines and Alkynes Catalyzed by Magnetically Separable Copper Ferrite Nanoparticles

M. Lakshmi Kantam*a, Jagjit Yadava, Soumi Lahaa, Shailendra Jhab
a Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500007, India
Fax: +91(40)27160921; e-Mail: mlakshmi@iict.res.in;
b Department of Chemistry, Jadavpur University, 700032 Kolkata, India
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Publication Date:
12 June 2009 (online)

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Abstract

An efficient three-component coupling of aldehydes, amines and alkynes has been developed to prepare propargylamines in nearly quantitative yields using magnetically separable copper ferrite nanoparticles as catalyst. Structurally divergent aldehydes and amines were converted into the corresponding propargyl­amines. The reaction does not require any co-catalyst.

Key words

copper ferrite nanoparticles - propargylamines - three-component coupling - reusability

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Typical procedure for the preparation of CuFe 2 O 4 nanoparticles: CuFe2O4 nanoparticles were prepared by a soft chemical method - co-precipitation of Fe²+ and Cu²+ cations in strong alkaline media at room temperature.¹5a Dilute water solutions of FeCl2˙4H2O and CuCl2˙2H2O mixed in the ratio 2:1 with intensive stirring were used for that purpose. In a water solution, the chlorides of these elements exist in a complex form. When a concentrated solution of NaOH with pH 13 is added, the complexes turn into hydroxides and a black precipitate of CuFe2O4 is produced. After decanting, the precipitate is rinsed with distilled water until pH 7 and then dried.

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Typical procedure for A ³ coupling reaction: A mixture of benzaldehyde (1 mmol), piperidine (1.2 mmol), phenyl-acetylene (1.3 mmol) and CuFe2O4 nanoparticles (15 mg, 6.5 mol% of copper) in toluene (4 mL) was stirred in a round-bottomed flask at 80 ˚C under N2 atmosphere. After completion of the reaction, which was monitored by TLC, the reaction mixture was magnetically concentrated with the aid of a magnet to separate the catalyst and the catalyst was washed several times with Et2O. The reaction mixture was concentrated under reduced pressure to afford the crude product which, after chromatography on silica gel, gave the corresponding propargylamine, N-(1,3-diphenyl-2-propyn­-yl)piperidine.¹H NMR (200 MHz, CDCl3): δ = 7.64-7.56 (m, 2 H), 7.50-7.42 (m, 2 H), 7.36-7.18 (m, 6 H), 4.76 (s, 1 H), 2.55-2.52 (m, 4 H), 1.63-1.54 (m, 4 H), 1.51-1.42 (m, 2 H). ESI MS: m/z = 276 (M + H)+.