Provided are a novel pyrimidine compound that inhibits HER2 activity and exhibits brain penetration properties, or a salt thereof, and a pharmaceutical composition comprising the same.
A compound represented by the following formula (I), or a salt thereof: wherein R1 represents a C1-C4 alkyl group optionally having a C1-C4 alkoxy group as a substituent, or a C3-C4 cycloalkyl group; R2 represents a hydrogen atom, a halogen atom, a C1-C6 alkyl group optionally having 1 to 5 C1-C4 alkoxy groups or fluorine atoms each as a substituent(s), or a C1-C6 alkoxy group; R3 represents a hydrogen atom, or a C1-C4 alkyl group optionally having 1 to 5 fluorine atoms as a substituent(s); R4 represents a hydrogen atom or a C1-C4 alkyl group; and R5 represents a phenyl group optionally having 1 to 3 substituents selected from fluorine atoms and chlorine atoms.