N-(1-Oxy-2-picolyl)oxalamic acids as a new type of O,O-ligands for the Cu-catalyzed N-arylation of azoles with aryl halides in water or organic solvent†
Abstract
N-(1-Oxy-pyridin-2-ylmethyl)oxalamic acids (L3–L5) were identified as novel efficient ligands for copper-catalyzed C–N cross-coupling of azoles and aryl halides in water. The N-arylation of imidazoles, indoles and pyrazoles proceeded with moderate to excellent yields and complete selectivity over aromatic amines and phenols. Moreover, L5, which is also efficient in organic solvent with low catalyst loading, can be used to promote the N-arylation reactions with water-sensitive materials. The catalytic mechanism was proposed based on the results of several verification experiments which indicated that the ligands as new-type chelators may coordinate to Cu(I) with two oxygen atoms of N-oxide and amide in the coupling process.
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