Synthesis and pharmacological evaluation of conformationally restricted phenothiazine analogues.

The synthesis of 3-(dimethylamino)-2,3-dihydro-4-chloro-1H-pyrido[3,2,1-kl]phenothiazine, its 10-chloro analogue, and two chloro isomers of 2[(dimethylamino)methyl]-2,3-dihydro-1H-pyrido[3,2,1-kl]phenothiazine is described. In these compounds the side chain of chlorpromazine is fixed into a certain position in order to study the dopamine-overlap theory and the role of the substituents in the phenothiazine neuroleptics. The compounds were tested for their influence on dopamine metabolism, while for the second set their ability to displace [3H]spiroperidol from dopamine receptors was assessed. No neuroleptic activity was found from the pharmacological data. The results are discussed on the basis of conformational requirements for dopamine antagonistic activity.