Chiral Cyclopropenyl Ketones: Reactive and Selective Diels–Alder Dienophiles
摘要:
The synthesis and Diels-Alder reactions of cyclopropenyl ketones are described. Cyclopropenyl ketones are highly reactive dienophiles that can engage a range of cyclic dienes and 2,3-dimethylbutadiene. The strategy of using cyclopropenyl ketones to facilitate Diels-Alder reactions is not limited to products that contain three-membered rings, as reductive opening by SmI2 can be used to produce a product that lacks a cyclopropane but retains a quaternary stereogenic center.
描述了使用环丙烯基酮进行半胱氨酸烷基化的方法。由于环丙烯应变能的显着释放,硫醇与环丙烯基酮的反应既快速又不可逆,并产生稳定的共轭加合物。所得的环丙烯基酮具有低分子量,并允许经由N-羟基琥珀酰亚胺(NHS)-酯简单地连接酰胺。虽然环丙烯基酮确实对水显示出较慢的背景反应性,但硫醇标记的速度要快得多。环丙烯基酮与谷胱甘肽(GSH)的反应以595 M -1 s -1的速率进行在pH 7.4的PBS中比α-卤代羰基标记试剂要快得多,并且与马来酰亚胺/硫醇偶联剂竞争。该方法已在蛋白质偶联中得到证明,并且在GSH或人血浆中长时间孵育后,芳基硫醇盐偶联物被证明是稳定的。最后,使用环丙烯基酮来生成基于PEG的水凝胶,该凝胶对在还原环境中的长时间孵育稳定。