Novel compounds of the formula <IMAGE> I wherein R1 is lower-alkyl, lower-alkoxy-lower-alkyl, lower-alkylthio-lower-alkyl or furyl, R2 is lower-alkyl, phenyl-lower-alkyl or cyclohexyl-lower-alkyl, each of R3 and R6 independently is hydrogen or fluorine, each of R4 and R5 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 <IMAGE> II wherein R2 is lower-alkyl, phenyl-lower-alkyl or cyclohexyl-lower-alkyl, each of R3 and R6 independently is hydrogen or fluorine, each of R4 and R5 independently is hydrogen or lower-alkoxy or together are methylenedioxy, ethylendioxy or ethylenoxy and n is an integer from 1 to 3.
TETRAHYDRONAPHTHALENE DERIVATIVES FOR IMPROVING SHORT-TERM MEMORY