Synlett 2003(13): 2071-2073  
DOI: 10.1055/s-2003-41476
LETTER
© Georg Thieme Verlag Stuttgart · New York

Highly Efficient C-O Cross-Coupling Reactions with Unactivated Halides by Ligandless, Heterogeneous Raney Ni-Al Alloy/Copper (I) Salts

Li-Wen Xu, Chun-Gu Xia*, Jing-Wei Li, Xiao-Xue Hu
State key Laboratory of Oxo Synthesis & Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, P R China
Fax: +86(931)8277088; e-Mail: cgxia@ns.lzb.ac.cn;
Further Information

Publication History

Received 4 August 2003
Publication Date:
08 October 2003 (online)

Abstract

A general, novel, ligandless and efficient method was developed for the Raney Ni-Al alloy/copper co-catalyzed formation of diaryl ethers by C-O cross-coupling reaction from aryl iodides, bromides, and even aryl chlorides with phenols.

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Typical Experimental Procedure. An oven-dried resealable Schlenk tube was fitted with a rubber septum and was cooled to room temperature under N2 purge. The septum was removed, and the tube was charged with CuI (10 mol%), 10-50 mg Raney Ni-Al alloy, K2CO3 (2.0 mmol), aryl halides (1.0mmol), and phenols (1.2-1.4 mmol). The tube was capped with the septum and purged with N2, and then dioxane(2ml) was added through the septum. The reaction mixture was stirred at 110 °C for 12-24 h (reaction times were not optimized). The reaction mixture was allowed to cool to room temperature and then diluted with ether and poured into a separating funnel. The mixture was washed with 1 M NaOH and brine, and then the organic fraction was dried over anhydrous magnesium sulfate, filtered, and concentrated. The crude material was purified by flash chromatography on silical gel.

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All the products were identified by NMR and GC-MS (Agilent 6890N GC/5973N MS, HP-5MS). Selected data for the product of entry 13: 1H NMR (300 MHz, CDCl3): 7.86 (d, J = 8.7 Hz, 2 H), 7.41-6.92 (18 H), 6.81 (d, J = 8.4 Hz, 2 H); 13C NMR (300 MHz, CDCl3): 157.45, 152.54, 134.19, 129.705, 129.58, 129.26, 128.01, 126.55, 125.75, 124.59, 123.19, 122.64, 119.27, 118.88.