Synlett 2006(14): 2195-2198  
DOI: 10.1055/s-2006-949615
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Mild and Efficient Method for N-Arylation of Nitrogen Heterocycles with Aryl Halides Catalyzed by Cu(II)-NaY Zeolite

M. Lakshmi Kantam*a, B. Purna Chandra Raoa, B. M. Choudary*b, R. Sudarshan Reddya
a Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad - 500 007, India
Fax: +91(40)27160921; e-Mail: mlakshmi@iict.res.in;
b Ogene Systems (I) Pvt. Ltd., # 11-6-56, GSR Estates, Moosapet, Hyderabad -500 037, India
e-Mail: bmchoudary@gmail.com;
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Publikationsverlauf

Received 28 December 2005
Publikationsdatum:
24. August 2006 (online)

Abstract

A mild and efficient method for N-arylation of nitrogen-containing heterocycles with aryl halides to afford N-arylheterocycles in excellent yields using a Cu(II)-NaY catalyst in the presence of K2CO3 base is reported.

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Catalyst preparation: Cu(II)-NaY zeolite was prepared by ion-exchange of zeolite NaY (10 g) with a solution of copper(II) acetate (2.86 g, 15.75 mmol in deionized water (150 mL) at r.t. for 24 h. The material was recovered by filtration, dried (110 °C) and calcined (550 °C) in a flow of air. AAS analysis showed that the zeolite contained 6.84 wt% of Cu.

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Typical Experimental Procedure: A mixture of 4-bromo-toluene (1 mmol), imidazole (1.2 mmol), K2CO3 (2 mmol) and Cu(II)-NaY (100 mg) in DMF (3 mL) was heated to 120 °C for the specified time (Table [2] ). The progress of the reaction was monitored by GC or TLC. The reaction mixture was filtered to separate the catalyst and the filtrate was quenched with aq NaHCO3 and the product extracted with EtOAc. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated. The residue was purified by column chromatography to afford pure 1-(4-methylphenyl)-1H-imidazole.
1-(4-Methylphenyl)-1 H -imidazole (Table [2] , entry 7). 1H NMR (CDCl3): δ = 7.76 (br s, 1 H), 7.24 (br s, 4 H), 7.19 (br s, 1 H), 7.13 (br s, 1 H), 2.39 (s, 3 H); MS (EI): m/z (%) = 158, 131, 104, 91 (100) 50; Anal. Calcd for C10N2H10: C, 75.95; N, 17.72; H, 6.33. Found: C, 76.09; N, 17.75; H, 6.16.
1-(4-Nitrophenyl)-1 H -imidazole (Table [2] , entry 1): mp 203 °C; 1H NMR (CDCl3): δ = 8.37 (d, J = 9.0 Hz, 2 H), 7.93 (br s, 1 H), 7.58 (d, J = 9.0 Hz, 2 H), 7.32 (br s, 1 H), 7.24 (br s, 1 H); MS (EI): m/z (%) = 189 (100), 159, 141, 116, 89, 50; Anal. Calcd for C9N3O2H7: C, 57.14; N, 22.2; H, 3.7; Found C, 57.42; N, 22.59; H, 3.19.
All products are reported compounds and have been identified by 1H NMR and mass spectrometric data. [5]