| 摘要 |
There are disclosed novel compounds of the formula <IMAGE> where X is hydrogen, loweralkyl, loweralkoxy, hydroxy, halogen, nitro or trifluoromethyl; R1 is hydrogen or loweralkyl; R2 is hydrogen, loweralkyl, arylloweralkyl or -(CH2)mR7 wherein m is 1, 2 or 3 and R7 is cyano or amino; R3 and R4 are independently hydrogen or loweralkyl; R5 and R6 are independently hydrogen or loweralkyl, or R5+R6 taken together with the carbon atom to which they are attached constitute a cyclobutane, cyclopentane, cyclohexane, cycloheptane, pyrrolidine, piperidine, morpholine or thiomorpholine ring, or R5 is hydrogen and R6 is aryl or -CH2OR8 wherein R8 is hydrogen, loweralkyl or loweralkylcarbonyl, which are useful for enhancing memory.
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