Vanillin derivative compounds inducing selective degradation of PLK1

A compound represented by Formula I, a stereoisomer thereof, or a pharmaceutically acceptable salt thereof:

• wherein
• PTM is PLK1 binding moiety represented by Formula (II):
• wherein * indicates the attachment point of the linker;
• ULM is CRBN E3 ubiquitin ligase binding moiety represented by Formula (A):
• wherein X1 is —CH2— or —CO—;
• and
• ** indicates the attachment point of the linker;
• and
• the linker is *—(CH2CH2O)p—CH2CH2—NH—** or *—(CH2CH2CH2)q—CH2CH2—NH—**;
• wherein p is an integer from 1 to 4;
• q is an integer from 1 to 4;
• and
• * and ** indicate the attachment points of the linker to the PTM and ULM moieties, respectively.