Palladium-Catalyzed Monoarylation of Aryl Amine with Aryl Tosylates

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

References and Notes

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14

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.