| 摘要 |
Compounds of formula (I) are described, which are selective inhibitors of phosphodiesterase, their pharmaceutically acceptable salts or their configuration isomers. R1 and R2 may be the same or different, and independently be C1-6 alkyl, and preferably methyl, more preferably, R1 and R2 are both in the cis-form of piperazine ring and are both methyl. Also provided is a method for preparing the compounds of formula (I), and intermediates which are involved in the routes of synthesizing the compounds of formula (I). The compounds of formula (I) are effective in treating impotence diseases, especially in treating male erectile dysfunction. They also have such characteristics as longer duration of effect and lower toxicity.
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