Synthesis and Oxidant Properties of Phase 1 Benzepine N-Oxides of Common Antipsychotic Drugs

Abstract

There is increasing evidence that cell constituents are oxidized by widely used antipsychotic drugs but until now the underlying chemistry has remained unclear. It is well known that such drugs readily undergo N-oxidation as a first key metabolic step. To gain insight into the problem, the tertiary phase 1 N-oxides of clozapine, olanzapine, quetiapine, and zotepine were synthesized, together with the N,S-dioxides of quetiapine and zotepine. These N-oxides were then subjected to well-established chemical transformations to test their oxidant properties in group VIII transition-metal­-catalyzed reactions. In the osmium tetroxide catalyzed dihydroxylation of styrene or cinnamyl alcohol and in the tetrapropylammonium perruthenate catalyzed oxidation of cinnamyl alcohol, the benzepine N-oxides could be used as replacements for the standard oxidant, N-methylmorpholine N-oxide (NMO) with varying degrees of efficiency. From a chemical point of view, clozapine N-oxide displayed a comparable oxidation power to NMO, characterizing the benzepines as oxygen carriers. Moreover, quetiapine was found to be an excellent double oxygen acceptor, undergoing initial N-oxidation and subsequent S-oxidation. It is therefore worthwhile considering whether oxidative damage to the human body might be related to the potential redox properties of common antipsychotic drugs.