Substitution reaction of 10-chloro-8-methylsulfonyl-10,11-dihydrodibenzo[b,f]thiepin with 1-(3-hydroxypropyl)piperazine afforded the title compound IV which was transformed by selective oxidation reactions to the sulfoxide X, N-oxide XII and N,S-dioxide XIII. The secondary amine VII was prepared via the carbamate VI and oxidized to the sulfoxide XI. Reaction of 10-chloro-8-methylsulfonyl-10,11-dihydrodibenzo[b,f]thiepin with ethylenediamine gave the diamine XIV which was oxidized to the corresponding sulfoxide XV. Compounds IV, VII and X-XV are potential metabolites of the neuroleptic agent oxyprothepin (II); compounds VII, XI, XIV and XV are potential metabolites of methiothepin (I). Out of the compounds prepared, only the title compound IV preserves the neuroleptic character.