研究室工作進展 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.
亮點介紹
胍作為一類重要的含氮有機化合物，是許多生物活性物質的結構單元，同時也作為堿性催化劑在有機合成中有廣泛應用。胺對碳二亞胺的催化成胍（CGAC）反應，是一種直接的、原子經濟性的方法制備胍。因該反應的原子經濟性和胍的重要性，目前受到許多合成化學家和金屬有機化學家的廣泛關注。我們課題組在該領域做了系列的研究工作，例如: (1) 發現烷基鋁，Zn(OTf)2和稀土金屬催化劑等催化的高效合成胍的反應，并一鍋法高效構築了三氟甲基磺酸胍鹽；(2) 通過肼分子中N-N鍵的斷裂，實現了烷基锂催化的1,2-二芳基碳二亞胺的成胍反應構建胍；(3)無金屬催化劑的條件下三組分反應構建環狀胍。該系列成果發表在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選為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)。結合我們組和其他課題組的工作，從反應機理的角度詳細闡釋了該反應的發現，發展現狀與重要性。