New compounds of formula I (FORMULA) in which R1 is lower alkyl; R2 is hydrogen or lower alkyl; R3 and R4 each independently is hydrogen, lower alkyl halo, nitro, trifluoromethyl or lower alkoxy; R5 and R6 each independently is hydrogen or lower alkyl or R5 and R6 together with the nitrogen atom form a pyrrol-1-yl, piperidino or morpholino ring; R7 is hydrogen or lower alkyl; Alk1 and Alk2 each independently is a straight or branched chain lower alkylene having one to six carbon atoms; and X is oxa or thia, and therapeutically acceptable acid addition salts thereof. The above compounds are diuretic agents, which also possess anti-hypertensive activity. They may be used alone or with other diuretic agents. Pharmaceutical compositions containing the compounds and processes for preparing the compounds are also described.