研究室工作进展 Jun. 3rd, 2015
Mechanistic Considerations of the Catalytic Guanylation Reaction of Amines with Carbodiimides for Guanidine Synthesis
Ling Xu, Wen-Xiong Zhang,* and Zhenfeng Xi
Organometallics 2015, 34, 1787−1801 (Review).
Catalytic guanylation reaction of amines with carbodiimides has received the increasing attention because of the atom-economical preparation of guanidines since 2003. To date, more than forty catalysts including transition metals, main group and rare-earth metals have been designed and tested for the guanylation reaction to construct acyclic and cyclic guanidines. In this review, we present a mechanistic consideration on catalytic guanylation reaction of amines with carbodiimides for guanidine synthesis to elucidate its development and importance. Four different types of reaction mechanisms are well categorized: [2+2]-cycloaddition/protonation mechanism, insertion/protonation mechanism, activation of carbodiimide/nucleophilic addition/intramolecular protonation mechanism, and protonation/nucleophilic addition/disassociation mechanism. It is useful to understand this reaction processes and accelerate the rapid development in the related area to meet the needs of the growing guanidines.
亮点介绍
胍作为一类重要的含氮有机化合物，是许多生物活性物质的结构单元，同时也作为碱性催化剂在有机合成中有广泛应用。胺对碳二亚胺的催化成胍（CGAC）反应，是一种直接的、原子经济性的方法制备胍。因该反应的原子经济性和胍的重要性，目前受到许多合成化学家和金属有机化学家的广泛关注。我们课题组在该领域做了系列的研究工作，例如: (1) 发现烷基铝，Zn(OTf)2和稀土金属催化剂等催化的高效合成胍的反应，并一锅法高效构筑了三氟甲基磺酸胍盐；(2) 通过肼分子中N-N键的断裂，实现了烷基锂催化的1,2-二芳基碳二亚胺的成胍反应构建胍；(3)无金属催化剂的条件下三组分反应构建环状胍。该系列成果发表在Organometallics 2009, 28, 882–887；Org. Biomol. Chem. 2010, 8, 1816–1820；Organometallics 2011, 30, 5278–5283；Org. Biomol. Chem. 2012, 10, 6266–6270（被OBC选为Cover Picture）；Inorg. Chem. 2012, 51, 11941–11948；J. Org. Chem. 2014, 79, 12004–12009；Organometallics 2014, 33, 2784–2789；Org. Lett. 2014, 16, 6274–6277；Chem. Commun. 2015, 51, 254–265 ( Feature Article)。结合我们组和其他课题组的工作，从反应机理的角度详细阐释了该反应的发现，发展现状与重要性。