Synergistic effects within a C2-symmetric organocatalyst: the potential formation of a chiral catalytic pocket
作者:Joshua P. Delaney、Hannah L. Brozinski、Luke C. Henderson
DOI:10.1039/c3ob27250h
日期:——
This study describes the synthesis of five novel C2-symmetric organocatalysts that facilitate the on-water asymmetric aldol reaction at low catalyst loading (1 mol%) without the use of additives. Each catalyst is composed of two diprolinamide units joined by a symmetric alkyl bridging group allowing for systematic modulation of catalytic site proximity. Typically, catalysts in this manuscript which bear the catalytic units in close proximity gave the best reaction outcomes in terms of conversion (up to >99%), diastereomeric ratio (4/96, syn/anti) and enantiomeric excess (up to 97%). This effect has been attributed to the assembly of a chiral pocket, facilitated by hydrogen bonding at the oil-in-water interface.
本研究介绍了五种新型 C2 对称有机催化剂的合成,这些催化剂可在不使用添加剂的情况下,以较低的催化剂负载量(1 摩尔%)促进水上不对称醛醇反应。每种催化剂都由两个二烯丙基酰胺单元组成,并由一个对称的烷基桥基连接,从而可以系统地调节催化位点的邻近性。通常情况下,本手稿中催化位点距离较近的催化剂在转化率(高达 >99%)、非对映异构体比率(4/96,同/反)和对映异构体过量(高达 97%)方面的反应效果最好。这种效果归因于在水包油界面的氢键作用下形成的手性口袋。