The formation of C–N bonds with aryl amines is one of the most widely studied reactions in organic chemistry. Despite this, it is still highly challenging, often requiring expensive, precious metal-based catalysts. Here we report an easy catalyst-free methodology for constructing C–N bonds. The method, which proceeds via the in situ formation of closed ring amidinium ions, allows the preparation of a series of symmetrical and/or unsymmetrical aryl diamines in notably high yields (82–98%) and purity and with a variety of different substituents. The methodology is shown successful for the preparation of aryl diamines having para- and/or meta-substituted carboxyl, nitro, bromo, methoxy, or methyl groups. This green synthetic pathway, which is catalyst free, requires only three steps, and proceeds without the need for purification. Further, it is a new sustainable, economically viable method to achieve an otherwise challenging bond formation.

中文翻译：

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三步反应法无催化剂合成芳基二胺

与芳基胺形成C–N键是有机化学中研究最广泛的反应之一。尽管如此，它仍然是极具挑战性的，通常需要昂贵的贵金属基催化剂。在这里，我们报告了一种构建C–N键的简便，无催化剂的方法。该方法通过原位形成闭环idi离子进行，从而可以制备一系列对称和/或不对称的芳基二胺，其收率高（82-98％）和纯度，并且具有各种不同的取代基。已证明该方法可成功制备具有对位和/或间位的芳基二胺-取代的羧基，硝基，溴，甲氧基或甲基。这种无催化剂的绿色合成途径仅需三个步骤，并且无需纯化即可进行。此外，这是一种新的可持续的，经济上可行的方法，可以实现原本具有挑战性的键形成。