NIS-mediated oxidative cyclization of N-(2-trifluoromethyl-3-alkynyl) hydroxylamines: a facile access to 4-trifluoromethyl-5-acylisoxazoles

Abstract

A novel NIS-mediated oxidative cyclization of N-(2-trifluoromethyl-3-alkynyl)hydroxylamines is developed, which provides a facile access to 4-trifluoromethyl-5-acylisoxazoles in 33–91% yields. Various types of commonly used electrophilic halogen source such as ICl, I₂, NIS, NBS and NCS at different temperatures in various solvents were investigated. It was found that the NIS acts as both an oxidant and an electrophile for the present sequential transformation. The scope, mechanism and application of this NIS-mediated domino reaction for further synthetic transformation were studied.