Iminoxyl Radical-Promoted Dichotomous Cyclizations: Efficient Oxyoximation and Aminooximation of Alkenes

A novel iminoxyl radical-involved
metal-free approach to vicinal
oxyoximation and aminooximation of unactivated alkenes is developed.
This method utilizes the dichotomous reactivity of the iminoxyl radical
to furnish a general difunctionalization on alkenes using simple tert-butyl nitrite (TBN) as the iminoxyl radical initiator
as well the carbon radical trap. By using this protocol, oxime featured
4,5-dihydroisoxazoles and cyclic nitrones were facilely prepared from
β,γ- and γ,δ-unsaturated ketoximes, respectively.

本研究开发了一种涉及亚胺氧基自由基（iminoxyl radical）的无金属合成新策略，可实现未活化烯烃的邻位氧肟化（oxyoximation）与邻位氨基肟化（aminooximation）反应。该方法利用亚胺氧基自由基的双重反应性，以简单的亚硝酸叔丁酯（tert-butyl nitrite, TBN）同时作为亚胺氧基自由基引发剂与碳自由基捕获剂，完成了烯烃的通用双官能团化修饰。依托该反应体系，可分别从β,γ-不饱和酮肟与γ,δ-不饱和酮肟中便捷制备得到带有肟特征结构的4,5-二氢异恶唑（4,5-dihydroisoxazoles）与环状硝酮（cyclic nitrones）。