COMPOUND AND PREPARATION METHOD THEREFOR AND USES THEREOF

摘要

The present invention provides a compound and a preparation method therefor and uses thereof. The compound is a compound represented by formula I or an enantiomer, a diastereoisomer, a racemate, a pharmaceutically acceptable salt, a crystalline hydrate or a solvate thereof. In the compound represented by formula I, R1, R2, R3 and R4 are defined in the specification.