Studies on the preparation of N-alkyl-O-phenylhydroxylamines

Several possible routes to the title compounds have been investigated. The reaction of N-hydroxycarbamates (1) with diphenyliodonium bromide gave, unexpectedly, N-hydroxy-N-phenylcarbamates (2), while N-methyl-N-hydroxycarbamates (6) gave 2-(N-methyl-N-alkoxycarbonylamino)phenols (7). Mechanistic aspects of the N-arylations and subsequent rearrangements are discussed. The desired N-alkyl-O-phenylhydroxylamines were obtained by the reduction of O-phenyloximes (15) with sodium cyanoborohydride.