PURPOSE: To obtain new pharmacologically active tricyclic derivs. useful as anti-depression medicines, diuretics, antihypertensive agents, etc.

CONSTITUTION: The tricyclic derivs. are compds. of formula I (where X is N, S, NH or the like; Y is N, S, CH or the like; Z is N, S, C-alkyl or the like; R1 is H or an alkyl; R2 is H, a halogen or the like; and R3 and R4 are each H, OH, a lower alkoxy or the like or R3 and R4 bond to each other to form imino, hydroxy or the like), their pharmaceutically acceptable salts and their isomers, enantiomers and diastereoisomers separated or as mixtures, e.g. 5,10- dihydro-4,4-dioxothieno[3,2-C][2,1]benzothiazepine. The compds. of the formula I are obtd., e.g. by allowing compds. of formula II to react with aminoalkyl derivs. of formula III (where W is a reactive group such as Cl, Br or I; Alk is a 1-5C linear or branched chain alkyl; and R5 and R6 are each H, a lower alkyl or the like) in an org. solvent in the presence of an org. or inorg. base.