K2CO3-Mediated Intramolecular Oxa-Michael Cyclization of α,β–Unsaturated Ketoximes: Synthesis of Densely Arene-Substituted 2-Isoxazolines Bearing One Quaternary Center

An efficient K2CO3-mediated intramolecular oxa-Michael cyclization of β,β-diarylated-α,β-unsaturated ketoximes has been described. This methodology features arene-rich 2-isoxazoline derivatives bearing one quaternary center in excellent yields with operationally simple experimental procedure. The deuterium scrambling experiments were carried out to shed light on the reaction pathway. To further demonstrate the synthetic utility of the method, a large-scale synthesis and Ullmann-type C-N bond formation reaction between pyrazole and dibrominated-isoxazoline have been performed.