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Synlett 2006(14): 2246-2250  
DOI: 10.1055/s-2006-949623
LETTER
© Georg Thieme Verlag Stuttgart · New York

Cellulose-Supported Copper(0) Catalyst for Aza-Michael Addition

K. Rajender Reddy*, Nadakudity S. Kumar
Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 007, India
Fax: +91(40)27160921; e-Mail: rajender@iict.res.in;
Further Information

Publication History

Received 2 March 2006
Publication Date:
24 August 2006 (online)

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Abstract

Cellulose-supported copper(0) efficiently catalyzes the aza-Michael reaction of N-nucleophiles, such as amines and imidazoles with α,β-unsaturated compounds to produce the corresponding β-amino compounds and N-substituted imidazoles in excellent yields. The reactions are facile and the recovered catalyst is used for several cycles with consistent activity.

Key words

cellulose - copper - aza-Michael - amines - imidazoles - α,β-unsaturated compounds - β-amino compounds - N-substituted imidazoles

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Typical Experimental Procedure for the Conjugate Addition of Amines to α,β-Unsaturated Compounds: In a typical procedure, α,β-unsaturated compound (1.0 mmol), amine (1.0 mmol) and catalyst (1.2 mol%) were taken in MeOH (5 mL) and stirred at r.t. for the appropriate time. After completion of the reaction as monitored by TLC, the reaction mixture was filtered and washed with MeOH (3 × 5 mL). The resulting reaction mixture was concentrated under reduced pressure. The crude product was purified by column chromatography to afford the pure product. All the products gave satisfactory NMR data and mass spectral data. [9] [11] [15] [17b] [c]

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Typical Experimental Procedure for the Conjugate Addition of Imidazole to α,β-Unsaturated Compounds: In a typical procedure, α,β-unsaturated compound (1.0 mmol), imidazole (1.0 mmol) and catalyst (3.6 mol%) were taken in toluene (5 mL) and stirred at reflux temperature for 12 h. The resulting reaction mixture was filtered and washed with EtOAc (3 × 5 mL) and concentrated under reduced pressure. The crude product was purified by column chromatography to afford the pure product. All the products gave satisfactory NMR data and mass spectral data. [12a] [29]
tert-Butyl-3-(1H-1-imidazolyl)propanoate (Table [2] , Entry 5): 1H NMR (200 MHz, CDCl3): δ = 7.44 (s, 1 H), 6.97 (s, 1 H), 6.87 (s, 1 H), 4.21 (t, J = 6.80 Hz, 2 H), 2.66 (t, J = 6.80 Hz, 2 H), 1.41 (s, 9 H). MS (70 eV): m/z = 196 [M+].