Novel compounds of formula (I), processes for their preparation, and their use as pharmaceutical agents are described: ##STR1## in which p represents an integer of 2 to 4; r represents an integer of 1 or 2; s represents 0 or 1; and X represents a group ##STR2## in which A.sub.1 is oxygen or sulphur, one of A.sub.2 and A.sub.3 is CR.sub.1 and the other is nitrogen or CR.sub.2, or A.sub.2 is oxygen or sulphur, A.sub.1 is CH and A.sub.3 is CR.sub.1, where R.sub.1 and R.sub.2 are independently selected from hydrogen and C.sub.1-2 alkyl, with the proviso that when r is 2, R.sub.1 and R.sub.2 are hydrogen or methyl. The novel compounds of this invention may be used to treat or to prevent dementia in mammals.
                            描述了化合物(I)的新颖化合物、其制备方法以及作为药物代理的用途:##STR1## 其中p代表2到4的整数;r代表1或2的整数;s代表0或1;X代表一个基团##STR2## 其中A.sub.1是氧或
硫,A.sub.2和A.sub.3中的一个是CR.sub.1,另一个是氮或CR.sub.2,或者A.sub.2是氧或
硫,A.sub.1是CH,A.sub.3是CR.sub.1,其中R.sub.1和R.sub.2分别独立选择自氢和C.sub.1-2烷基,但当r为2时,R.sub.1和R.sub.2为氢或甲基。本发明的新化合物可用于治疗或预防哺乳动物的痴呆症。