Pyrimidopyrazolone derivative as Wee1 inhibitor and use thereof

A compound of formula (I), or a stereoisomer or a pharmaceutically acceptable salt thereof,

• wherein,
• is a single bond or a double bond;
• n is 1, 2 or 3;
• ring A is selected from the group consisting of C6-10 aryl and 5-12 membered heteroaryl;
• R1 is selected from the group consisting of H and C1-3 alkyl, wherein the C1-3 alkyl is optionally substituted by 1, 2 or 3 Ra;
• R2 and R3 are each independently selected from the group consisting of H, F, Cl, Br, I, OH, NH2 and C1-3 alkyl, wherein the C1-3 alkyl is optionally substituted by 1, 2 or 3 Rb, and R2 and R3 are not H at the same time;
• R4 is selected from the group consisting of C3-8 cycloalkyl and 4-10 membered heterocycloalkyl, wherein the C3-8 cycloalkyl and 4-10 membered heterocycloalkyl are optionally substituted by 1, 2 or 3 Rc;
• R5 is selected from the group consisting of H, F, Cl, Br, I, OH, NH2, C1-3 alkyl and C1-3 alkoxy, wherein the C1-3 alkyl is optionally substituted by 1, 2 or 3 Rd;
• Ra is each independently selected from the group consisting of F, Cl, Br, I, OH and NH2;
• Rb is each independently selected from the group consisting of F, Cl, Br, I, OH and NH2;
• Rc is each independently selected from the group consisting of H, F, Cl, Br, I, OH, NH2 and C1-3 alkyl, wherein the NH2 is optionally substituted by 1 or 2 R, and the C1-3 alkyl is optionally substituted by 1, 2 or 3 R;
• Rd is each independently selected from the group consisting of F, Cl, Br, I, OH and NH2;
• R is each independently selected from the group consisting of F, Cl, Br, I, OH and NH2;
• the 5-12 membered heteroaryl and 4-10 membered heterocycloalkyl contain 1, 2, 3 or 4 heteroatoms or heteroradicals independently selected from the group consisting of —NH—, O, —S— and N.