Potential metabolites of tricyclic neuroleptics: 3,7-Dimethoxy and 7,8-dimethoxy derivatives of 10-(4-methylpiperazino)-10,11-dihydrodibenzo[b,f]thiepin

Reaction of 2-iodo-4-methoxybenzoic acid with 3-methoxythiophenol resulted in the acid II which was transformed via the alcohol III and the nitrile IV to [4-methoxy-2-(3-methoxyphenylthio)phenyl]acetic acid ( V ). Reaction of (2-iodophenyl)acetic acid with 3,4-dimethoxythiophenol gave the isomeric [2-(3,4-dimethoxyphenylthio)phenyl]acetic acid ( XI ). Acids V and XI afforded by cyclization the ketones VIa and VIb which were converted by reactions with 1-methylpiperazine and titanium tetrachloride to the enamines IXa and IXb . Reduction of these enamines with diborane led to the title compounds. Attempts to reduce the enamines with zinc in acetic acid resulted in hydrogenolysis, the main products being 2,3-dimethoxy- and 3,7-dimethoxy-10,11-dihydrodibenzo[ b,f ]thiepin ( Xab ).