摘要 |
Compounds having the structure <IMAGE> and the pharmaceutically acceptable salts thereof; wherein Z is oxygen, sulfur or methylene; R1 is hydrogen, halogen, alkyl, aryl or arylalkyl; R2 is hydrogen, alkyl, aryl, or arylalkyl; R3 is hydrogen, alkyl, aryl or arylalkyl; and R4 is hydrogen, halogen, alkyl, phenyl, dialkylamidosulfonyl or trifluoromethyl; have useful central nervous system activity.
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