Novel compounds of the formula ##STR1## wherein R.sup.1 is lower-alkyl, lower-alkoxy-lower-alkyl, lower-alkylthio-lower-alkyl or furyl, R.sup.2 is lower-alkyl, phenyl-lower-alkyl or cyclohexyl-lower-alkyl, each of R.sup.3 and R.sup.6 independently is hydrogen or fluorine, each of R.sup.4 and R.sup.5 independently is hydrogen or lower-alkoxy or together are methylenedioxy, ethylenedioxy or ethylenoxy and n is an integer from 1 to 3, have a pronounced activity in counteracting cerebral insufficiency or improving cognitive functions and also reduce the multiple-resistance towards cytostatics in the treatment of tumors or of chloroquine resistance in the treatment of malaria. They can accordingly be used as medicaments, especially for the control or prevention of cerebral insufficiency or for the improvement of cognitive functions. The novel compounds of formula I can be manufactured by O-acylating a likewise novel compound of the formula ##STR2## wherein R.sup.2 is lower-alkyl, phenyl-lower-alkyl or cyclohexyl-lower-alkyl, each of R.sup.3 and R.sup.6 independently is hydrogen or fluorine, each of R.sup.4 and R.sup.5 independently is hydrogen or lower-alkoxy or together are methylenedioxy, ethylendioxy or ethylenoxy and n is an integer from 1 to 3.
公式为##STR1##的新化合物,其中R.sup.1是较低的烷基,较低的烷氧基较低的烷基,较低的烷
硫基较低的烷基或
呋喃基,R.sup.2是较低的烷基,苯基较低的烷基或环己基较低的烷基,R.sup.3和R.sup.6中的每一个独立地是氢或
氟,R.sup.4和R.sup.5中的每一个独立地是氢或较低的烷氧基,或者一起是亚甲二氧基,乙二氧基或
乙烯氧基,n是1到3的整数,这些化合物在对抗脑缺血或改善认知功能方面具有显著的活性,并且还减少了肿瘤治疗中对细胞毒药物的多重耐药性或疟疾治疗中对
氯喹耐药性。因此,它们可以作为药物使用,特别用于控制或预防脑缺血或改善认知功能。公式I的新化合物可以通过对一种同样新颖的化合物进行O-酰化而制备,该化合物的公式为##STR2##其中R.sup.2是较低的烷基,苯基较低的烷基或环己基较低的烷基,R.sup.3和R.sup.6中的每一个独立地是氢或
氟,R.sup.4和R.sup.5中的每一个独立地是氢或较低的烷氧基,或者一起是亚甲二氧基,乙二氧基或
乙烯氧基,n是1到3的整数。