Abstract: Compounds of formula I or I', ##STR1## wherein X and Y are independently selected from hydrogen, halo, and (1-6C)alkoxy;R.sup.1 is selected from(A) (1-6C)alkyl;(B) phenyl and naphthyl or substituted versions thereof;(C) phenyl (1-3C)alkyl and naphthyl (1-3C) alkyl;(D) five- and six-membered heteroaryl rings;(E) heteroaryl (1-3C)alkyl and pharmaceutically acceptable salts thereof, useful in the treatment of neuropsychiatric disorders such as psychoses; pharmaceutical compositions comprising a compound of formula I or I' and a pharmaceutically acceptable diluent or carrier; and methods of treating neuropsychiatric disorders comprising administering to a mammal (including man) in need of such treatment an effective amount of a compound of formula I or I', or a pharmaceutically acceptable salt thereof are claimed. The invention also relates to novel processes for producing enantiomeric methanoanthracenyl sulfoxides.