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来源：百度知道 编辑：UC知道 时间：2024/06/04 18:59:24
Copper salts and complexes have been extensively utilized as catalysts for the Chan-Lam reaction between boronic acids and amines. However, to the best of our knowledge, the employing of aqueous ammonia in Chan-Lam reaction was rarely reported or studied before.8 We envisioned that the in situ formed copper(II)/NH3 complex would be an efficient catalyst for such transformation. Herein, we wish to report a simple and cheap copper(II)-catalyzed coupling reaction of aqueous ammonia with arylboronic acids, providing the symmetric di-aryl amines in good to excellent yields.
Initial studies were conducted using aqueous ammonia (3 equiv) and phenylboronic acid (1a) (0.2 mmol) in 1,2-dichloroethane (DCE) as a model reaction under air in the presence of Cu(OAc)2.H2O (20 mol %). Disappointingly, after the extensive screening of copper sources and solvents, no synthetically useful results were obtained. We realized that the distribution of the in situ formed copper species depended on the
Initial studies were conducted using aqueous ammonia (3 equiv) and phenylboronic acid (1a) (0.2 mmol) in 1,2-dichloroethane (DCE) as a model reaction under air in the presence of Cu(OAc)2.H2O (20 mol %). Disappointingly, after the extensive screening of copper sources and solvents, no synthetically useful results were obtained. We realized that the distribution of the in situ formed copper species depended on the
铜盐和配合得到了广泛用作催化剂的赞林反应硼酸酸和胺。然而，据我们所知，用人的氨水中赞林的反应是很少被报告或研究before.8我们设想，在原地形成铜（ II ） /氨复杂的将是一个有效的催化剂，这种转变。在此，我们要报告一个简单而廉价的铜（ II ）催化偶联反应的氨水与arylboronic酸，提供对称二芳基胺的优良率。
进行了初步研究使用氨水（ 3同等学历） ，并phenylboronic酸（ 1A ）款（ 0.2浓度）在二氯乙烷（二氯乙烯）为模型反应下空气中存在的Cu （醋酸） 2.H2O （ 20摩尔％ ） 。令人失望的是，经过了广泛的筛选铜来源和溶剂，没有任何有用的结果综合得到。我们认识到，分布在原地形成铜物种取决于碱度的反应体系，将有很大的影响的反应。因此，苯甲酸添加到调整碱度的反应体系的一系列溶剂。我们高兴的是，在场的0.5当量苯甲酸，收率提高到50 ％的DCE （表1 ，进入1 ） 。在溶剂测试，丙酸乙酯是最好的和产量大幅增加90 ％ ，在场的0.5当量苯甲酸（表1 ，进入6 ） 。其他类，如甲苯磺酸，醋酸和甲酸也有效的这种转变和苯甲酸是最好的（表1 ，项目7-9 ） 。进一步调查显示，该数额的苯甲酸有重大影响的反应。几个铜（ ΙΙ ）来源也受到审查，和铜（醋酸） 2.H2O原来是优于其他的。没有形成产品的情况下铜（ ΙΙ ） 。