strategy for the regioselective assembly of 2-aminoimidazole derivatives is herein described. Through a transition metal-free domino addition/cyclization process, the reactions of unsymmetrical carbodiimides with propargylic amines mediated by Cs2CO3 selectively afforded the corresponding polysubstituted 2-aminoimidazoles in moderate to good yields under very mild conditions. The regioselectivity was reversed
本文描述了2-氨基咪唑衍生物的区域选择性组装的方便的单步策略。通过无过渡金属的多米诺加成/环化过程,不对称碳二亚胺与Cs 2 CO 3介导的炔丙基胺的反应在非常温和的条件下以中等至良好的收率选择性地提供了相应的多取代的2-氨基咪唑。在较高温度下,在TEA存在下,区域选择性反转。所获得的2-(邻碘芳基)氨基咪唑可以容易地转化为2-(2-联苯基)氨基咪唑,2-(邻炔基苯基)氨基咪唑,苯并咪唑并[1,2- a ]咪唑和N-(咪唑-2-基)吲哚衍生物。
A greener synthetic protocol for the preparation of carbodiimide
作者:Abdur Rezzak Ali、Harisadhan Ghosh、Bhisma K. Patel
DOI:10.1016/j.tetlet.2009.12.017
日期:2010.2
A new and facile preparation of symmetrical and unsymmetrical 1,3-diaryl and aryl-alkyl carbodiimides via a dehydrosulfurisation of their corresponding thioureas is described. Herein, the classical method of oxidative desulfurisation of thiourea to carbodiimide involving toxic heavy metal oxides (HgO) has been replaced with an easily available, cost-effective and environmentally benign reagent, iodine. Simple reaction conditions, easy purification of the products and high yields are important attributes of the present methodology and perhaps the best alternative from a green chemistry perspective. The only limitation to this method however, is in the preparation of 1,3-dialkyl Substituted carbodiimide. (C) 2009 Elsevier Ltd. All rights reserved.