1,4-Substituted piperazinyl derivatives useful as psychostimulants

A compound of formula I, ##STR17## wherein each of R.sub.1 and R.sub.4, which may be the same or different, is hydrogen, halogen of atomic number from 9 to 35, alkyl of 1 to 4 carbon atoms or alkoxy of 1 to 4 carbon atoms,

• either each of R.sub.2 and R.sub.3 is hydrogen or R.sub.2 and R.sub.3 together are oxygen,
• either B and D together with the carbon atoms to which they are bound form a benzene ring, or
• B is sulphur and B and D together with the carbon atoms to which they are bound form a thiophene ring which may be substituted in the position .alpha.- to the sulphur atom with halogen of atomic number from 9 to 35 or alkyl of 1 to 4 carbon atoms, and
• when B and D together with the caron atoms to which they are bound form a benzene ring,
• A is oxygen, sulphur, --CH.sub.2 --O-- or --CH.sub.2 --S-- in either orientation, or
• when B is sulphur and B and D together with the carbon atoms to which they are bound form a substituted or unsubstituted thiophene ring,
• A is a group of formula ##STR18## wherein each of R.sub.7 and R.sub.8, which may be the same or different, is hydrogen or alkyl of 1 to 4 carbon atoms and either each of E and F is hydrogen or E and F together form a bond,
• or a pharmaceutically acceptable acid addition salt thereof.