The incorporation of a gem-dimethyl group at the 5-position of a chiral oxazolidinone biases the conformation of the adjacent C(4)-stereodirecting group such that the gem-dimethyl-4-iso-propyl combination mimics a C(4)-tert-butyl group, providing higher levels of stereocontrol than a simple 4-iso-propyloxazolidinone. The generality of this principle is demonstrated with applications in stereoselective enolate alkylations, kinetic resolutions, Diels–Alder cycloadditions and Pd-catalysed asymmetric acetalisation reactions.
在手性
噁唑啉酮的5位引入一个双甲基基团会使得邻近的C(4)立体导向基团倾向于特定构象,即双甲基-4-异丙基的组合能模拟一个C(4)叔丁基基团,从而实现更高的立体控制
水平,优于简单的4-异丙基
噁唑啉酮。这一原理的普遍性在立体选择性烯醇化物烷基化、动力学拆分、狄尔斯-阿尔德环加成和
钯催化的不对称
缩醛化反应中得到了应用验证。