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Synlett 2011(7): 955-958  
DOI: 10.1055/s-0030-1259728
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Palladium-Catalyzed Monoarylation of Aryl Amine with Aryl Tosylates

Xiaomin Xie*a, Gang Nib, Fangfang Maa, Lina Dingc, Sheng Xu*b, Zhaoguo Zhanga
a School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240,P. R. of China
Fax: +86(21)54748925; e-Mail: xiaominxie@sjtu.edu.cn;
b School of Chemistry and Molecular Engineering, East China University of Science and Technology, 130 Meilong Road,Shanghai 200237, P. R. of China
Fax: +86(21)64251851; e-Mail: xusheng@ecust.edu.cn;
c School of Chemistry Chemical Engineering & Materials, Heilongjiang University, 74 Xuefu Road, Harbin 150000, P. R. of China
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Publication History

Received 29 December 2010
Publication Date:
10 March 2011 (online)

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Abstract

The bulky and electron-rich MOP-type ligand was efficient for the Pd-catalyzed amination of aryl tosylates. The in situ generated Pd(0) was a more efficient catalyst precursor than Pd(dba)2. In the presence of Pd(OAc)2, PhB(OH)2, and a hindered and electron-rich MOP-type ligand, a variety of primary aryl amines reacted with various aryl tosylates to form the corresponding secondary aryl amines in high yields with high selectivity. Furthermore, the catalyst system was also efficient for the arylation of indoles and hydrazones with aryl tosylates.

Key words

palladium - ligand - monoarylation - aryl tosylate - aryl amine

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Typical Procedure
A flame-dried Schlenk tube was charged with Pd(OAc)2 (4.5 mg, 0.02 mmol), L1 (13.7 mg, 0.03 mmol), PhB(OH)2 (6.1 mg, 0.05 mmol), and n-BuOH (2 mL) under an atmosphere of nitrogen. The solution was stirred at r.t. for 15 min then K3PO4 (424.5 mg, 2.0 mmol) and ArOTs 1 (1mmol) were added, followed by aryl amine 3 (1.2 mmol). The reaction was heated to 110 ˚C and stirred for 15 h. The reaction mixture was cooled to r.t. and diluted with Et2O (5 mL) and H2O (3 mL). After separation of the layers, the aqueous phase was extracted with Et2O (3 × 5 mL), and the combined organic layers were dried over Na2SO4 and concentrated in vacuo. Purification of the crude product by flash column chromatography (silica gel; PE-Et3N, 99:1) yielded compound 3.