A compound having the formula or a pharmaceutically acceptable salt thereof wherein R is hydrogen or hydroxy; R1 is hydrogen, alkyl, arylalkyl, (CH2)nOH, or (CH2)nNR7R8; R5 and R6 are each independently hydrogen, halogen, NO2, CN, CF3, SO2NR7R8, PO3R9R10, alkyl, alkenyl, alkynyl, (CH2)nCONR7R8, (CH2)nCO2R10, NHCOR11, A is a ring formed by the following: a-NR12—CHR13—CHR14-b, a-CHR13—CHR14—NR12-b, a-CHR13—NR12—CHR14-b, a-CHR14—CH2—NR12—CHR13-b, a-CHR13—NR12—CH2—CHR14-b, a-CH2—CH2—CHR13—NR12-b, a-NR12—CHR13—CHR12—CH2—CH2-b, a-CH2—CH2—NR12—CH2—CH2-b, a-CH2—CH2—CH2NR12—CH2-b, a-CH2—NR12—CH2—CH2-b a-CH2—CH2—CH2—CH2—NR12-b, a-NR12—CH2—CH2—CH2—CH2-b, The compounds are useful in the treatment of disorders responsive to the blockade of glutamic and aspartic acid receptors.