摘要 |
The present application relates to compounds of the formula I <CHEM> 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. and a process for their preparation. The invention relates also to compounds of the formula II <CHEM> where X, R1 and R3 through R6 are as defined earlier and R9 is hydrogen or bromine (with the proviso that when R1=R3=R4=R5=R6=R9=H, X is not 7-chloro) which are also useful for enhancing memory and for preparing compounds of formula I. |