Design and Synthesis of Urea-Linked Aromatic Oligomers-A Route Towards Convoluted Foldamers
作者:James J. Mousseau、Liyan Xing、Nathalie Tang、Louis A. Cuccia
DOI:10.1002/chem.200901094
日期:2009.10.5
Herein we report the design and synthesis of crescent‐shaped and helical urea‐based foldamers, the curvature of which is controlled by varying the constituent building blocks and their connectivity. These oligomers are comprised of two, three or five alternating aromatic heterocycles (pyridazine, pyrimidine or pyrazine) and methyl‐substituted aromatic carbocycles (tolyl, o‐xylyl or m‐xylyl) connected
本文中,我们报告了月牙形和螺旋形脲基折叠剂的设计和合成,其曲率通过改变组成构件及其连通性来控制。这些低聚物是由两个,三个或五个交替的芳族杂环(哒嗪,嘧啶或吡嗪)和甲基取代的芳族碳环(甲苯基,的ø -二甲苯或米-二甲苯基)通过尿素键连接在一起。基于分子内氢键和空间相互作用,在这些π-共轭尿素连接的低聚物中编码月牙形构型偏好。曲率的程度由与杂环和芳基的尿素连接性来调节。这些折叠剂的NMR表征证实了溶液中哒嗪和嘧啶折叠剂中预期的分子内氢键构象(脲键的Z,E构型)。所述的X射线晶体结构Ñ 3,Ñ 6 -diisobutylpyridazine -4,6-二胺- ö甲苯基脲联foldamer(4)确认N的存在杂环氮原子和脲键的游离氢之间H⋅⋅⋅N氢键。另外,甲苯基甲基与脲羰基氧不利地相互作用,因此使交替的平面构象不稳定。