Cycloaddition of nitrile oxides to cyclic and acyclic α,β-unsaturated amides. Frontier orbital interactions and an unexpected steric drift determine regiochemistry
作者:Pierluigi Caramella、Daniela Reami、Mario Falzoni、Paolo Quadrelli
DOI:10.1016/s0040-4020(99)00331-2
日期:1999.5
The regiochemistry of the cycloadditions of nitrile oxides to α,β-unsaturated amides is determined by frontier orbital interactions and by a regiochemical drift due to steric effects. Cycloadditions to α,β-unsaturated lactames afford mainly 4-carboxamido-isoxazolines with high regioselectivity. In cycloadditions to acyclic α,β-unsaturated amides the regioselectivity relaxes and finally reverses in
氮氧化物与α,β-不饱和酰胺的环加成反应的区域化学作用取决于前沿的轨道相互作用和空间效应引起的区域化学漂移。α,β-不饱和内酰胺的环加成主要提供具有高区域选择性的4-羧酰胺基-异恶唑啉。在非环状α,β-不饱和酰胺的环加成反应中,由于N,N-二取代的衍生物的胺原子氮的空间拥挤增加,其区域选择性松弛并且最终逆转。