Highly diastereoselective 1,3-dipolar cycloadditions of chiral non-racemic nitrones to 1,2-diaza-1,3-dienes: an experimental and computational investigation
作者:Roberta Majer、Olga Konechnaya、Ignacio Delso、Tomas Tejero、Orazio A. Attanasi、Stefania Santeusanio、Pedro Merino
DOI:10.1039/c4ob01371a
日期:——
Asymmetric 1,3-dipolar cycloadditions between 1,2-diaza-1,3-dienes and chiral non-racemic nitrones to give 3-substituted-5-diazenyl isoxazolidines were studied both experimentally and theoretically. Whereas cyclic nitrones provide complete selectivity for the cycloaddition reaction (only one isomer is obtained), acyclic nitrones derived from D-glyceraldehyde and D-galactose lead to 1 : 1 mixtures of
通过实验和理论研究了1,2-二氮杂1,3-二烯与手性非外消旋硝基之间的不对称1,3-偶极环加成反应,得到3-取代的5-二氮杂异恶唑烷。环状硝酮为环加成反应提供了完全的选择性(仅获得一种异构体),而衍生自D-甘油醛和D-半乳糖的无环硝酮则形成了两种异构体的1:1混合物。基于反应性指数的DFT分析与二氮烯基的高吸电子特性相符,可以正确预测反应的区域化学。基于过渡态理论的考虑溶剂效应(PCM模型)的相同理论研究与观察到的实验结果在质量上也吻合。