A novel and mild method for the highly selective synthesis of asymmetric urea from amines and COS has been established. This method effectively synthesizes asymmetric urea from combinations of aliphatic primary amines and aliphatic secondary amines, as well as from sterically hindered aliphatic primary amines and aromatic primary amines. This breakthrough overcomes the previous limitation of using only aromatic amines and secondary amines for selective synthesis of asymmetric urea. Moreover, the method accommodates a wide range of substrates and demonstrates high tolerance to various functional groups, yielding diverse asymmetric ureas with good to excellent yields and selectivity. Mechanistic investigations reveal that the high selectivity is due to two-stage temperature regulation, the selection of specific substrate structures and ratios, and the appropriate amount of COS. Additionally, the H2S produced during the reaction is efficiently captured by the substrate or solvent, forming useful chemical products. This efficient synthetic methodology provides a mild and selective pathway for the preparation of asymmetric urea derivatives.

中文翻译：

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从 COS 和胺类中无催化剂合成不对称尿素：一种选择性调节策略


已经建立了一种从胺和 COS 高选择性合成不对称尿素的新型温和方法。该方法从脂肪族伯胺和脂肪族仲胺的组合以及空间受阻的脂肪族伯胺和芳香族伯胺中有效地合成不对称尿素。这一突破克服了以前仅使用芳香胺和仲胺选择性合成不对称尿素的局限性。此外，该方法适用于多种底物，并表现出对各种官能团的高耐受性，产生多种不对称尿素，具有良好到优异的产率和选择性。机理研究表明，高选择性是由于两阶段温度调节、特定底物结构和比例的选择以及适量的 COS。此外，反应过程中产生的 H2S 被底物或溶剂有效捕获，形成有用的化学产物。这种高效的合成方法为制备不对称尿素衍生物提供了一种温和的选择性途径。