Abstract Chlorpromazine N-oxide, fluphenazine N4′-oxide, prochlor-perazine N 4′-oxide, sulforidazine N-oxide, and trifluoperazine N 4′-oxide were synthesized by oxidation of the designated nitrogen atom in the N-10 side chain of the respective parent drug with 3- chloroperoxybenzoic acid. In the case of trifluoperazine, a stepwise increase in the amount of oxidant yielded the N 1′, N 4′-dioxide and N 1′, N 4′, S-trioxide. The N′, S- ...