Copper-catalyzed synthesis of oxime ethers from iminoxy radical (C[dbnd]N–O[rad]) and maleimides via radical addition

Abstract

An efficient Cu(II)-catalyzed radical addition of maleimides has been achieved. The identified copper catalyst enables the formation of oxime radicals (N–O) by cleaving the O–H bond in ketoximes, followed by the radical addition to N-substituted maleimides. The oxime radicals (N–O) were detected and confirmed by EPR spectroscopy and variable-temperature 1H NMR. The simple one-pot reaction realizes the facile preparation of a variety of oxime ether adduct products in moderate to good yields.