We report here that a series of bridged O,O-ketal fusedspiro piperidone-cyclopropane derivatives 3 can be constructed with excellent yields and good diastereoselectivity by the one-pot reaction of 1-acylcyclopropanecarboxamides 1 with electron-deficient alkene 2a (EWG = CHO) via the domino process involving [4 + 2] annulation/intermolecular electrophilic addition/intramolecular cyclization. Furthermore
Copper(I)-Catalyzed Intramolecular<i>N</i>-<i>N</i>Coupling of Cyclopropyl<i>O</i>-Acyl Ketoximes: Synthesis of Spiro-fused Pyrazolin-5-ones
作者:Zhiguo Zhang、Junlong Li、Guoqing Huang、Kai Sun、Guisheng Zhang、Nana Ma、Qingfeng Liu、Tongxin Liu
DOI:10.1002/cjoc.201600479
日期:2016.12
A convenient copper‐catalyzed approach has been developed for the synthesis of substituted spiro‐fused pyrazolin‐5‐ones from readily available cyclopropyl O‐acyl ketoximes via an intramolecular NN bond formation reaction. These catalytic reactions proceed in excellent yields with a broad scope.