Hexahydropentaleno derivatives, preparation method and use in medicine thereof

The invention relates to hexahydropentaleno derivatives, the preparation method and use in medicine thereof, and in particular to hexahydropentaleno derivatives or stereo-isomers or pharmaceutically acceptable salts thereof as shown in general formula (I), and to the preparation method therefor and pharmaceutical compositions comprising the derivatives, and to the use thereof as a therapeutical agent, especially as a DPP-IV inhibitor. The definition of each substituent in formula (I) is the same as the definition in the description.