Fluorinated tricyclic neuroleptics: Synthesis and pharmacology of 2-chloro-8-fluoro-4-(4-methylpiperazino)-4,5-dihydrothieno[2,3-b]-1-benzothiepin
Diazotization of 4-fluoroanthranilic acid (V) and the following reaction with sodium disulfide gave the dithio diacid VII which was reduced with lithium aluminium hydride to 4-fluoro-2-mercaprobenzyl alcohol (XI). Its reaction with 2-chloro-5-iodothiophene afforded the alcohol XIII which was transformed via the chloride XIV and the nitrile XV to [2-(5-chloro-2-thienylthio)-4-fluorophenyl]acetic acid (XVI). Cyclization with phosphorus pentoxide in toluene resulted in 2-chloro-8-fluorothieno[2,3-b]-1-benzothiepin-4(5H)-one (XVIII) which was converted via the alcohol XIX to the chloro derivative XX. The substitution reaction with 1-methylpiperazine led to the title compound IV which is a long-acting and very potent tranquillizer but did not reveal, in the animal tests performed, the properties of a neuroleptic agent.