The present invention relates to a compound of General Formula (I) below, among others. In the Formula, Ar1 is an optionally substituted aryl or heteroaryl group R1 is a hydrogen atom, an optionally substituted C1-C6 alkyl group, or an optionally substituted aryl, aralkyl, or heteroaryl group R2 is an optionally substituted aryl, aralkyl, or heteroaryl group and R3 is a hydrogen atom or a C1-C6 alkyl group. A compound of the present invention has an excellent Wee1 kinase inhibiting effect, and is therefore useful in the filed of medicine, particularly in various types of cancer therapy.
