A family of 6-hydroxypicolinamide ligands have been identified as effective supporting ligands for Cu-catalyzed couplings of heteroaryl bromides and chlorides with heteroaryl primary amines. The C–N couplings are carried out at 80–120 °C in DMSO or sulfolane using K₂CO₃ or K₃PO₄ as the base with 2–10 mol % CuI and supporting ligand. The strength of the base was found to have an impact on the chemoselectivity and rate. The use of K₂CO₃ as the base enabled selective C–N coupling of aryl bromides over aryl chlorides with 2–5 mol % Cu at 80–120 °C. With K₃PO₄ as the base, aryl chlorides are capable of undergoing C–N coupling, though 5–10 mol % Cu is required at 120–130 °C. Members of the ligand family are straightforward to prepare in one step from 6-hydroxypicolinic acid and the corresponding anilines.

中文翻译：

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铜催化杂芳基伯胺和（杂）芳基溴化物与6-羟基吡啶啉配体的偶联

已经确定了6-羟基吡啶甲酸酰胺配体家族是Cu催化的杂芳基溴化物和氯化物与杂芳基伯胺的偶联的有效支撑配体。C–N偶联是在80–120°C的DMSO或环丁砜中，以2-10 mol％CuI和支持配体的K ₂ CO ₃或K ₃ PO ₄为碱进行的。发现碱的强度对化学选择性和速率有影响。使用K ₂ CO ₃作为碱，可以在80–120°C的条件下，以2–5 mol％的Cu在芳基氯上进行芳基溴的选择性C–N偶联。含K ₃ PO ₄作为基础，芳基氯化物能够进行C–N偶联，尽管在120–130°C下需要5–10 mol％的Cu。配体家族的成员可以直接一步一步由6-羟基吡啶甲酸和相应的苯胺制备。