| 摘要 |
This invention provides thiadiazinone derivatives represented by the following formula (I) <IMAGE> (I) wherein R1 represents a hydrogen atom or C1-C5 alkyl, R2 represents a 5- or 6-membered heterocyclic ring having (a) 1-3 nitrogen atoms, (b) a oxygen atom, (c) one sulfur atom, (d) 1-3 nitrogen atoms and one oxygen atom, or (e) 1-3 nitrogen atoms and one sulfur atom each of which rings may optionally be substituted by at least one substituent selected from the group consisting of C1-C5 alkyl, cyano, hydroxy, C1-C5 alkoxy, amino, C1-C5 alkylamino, C2-C6 dialkylamino, C2-C5 acylamino, carboxyl, C2-C5 alkoxycarbonyl and carbamoyl; or a pharmaceutically acceptable salt thereof. The compounds according to the present invention have an excellent cardiotonic activity, and are useful as active ingredients of a cardiotonic drug.
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