HistoneH2A mono-ubiquitination plays important roles in epigenetic gene expression and is also involved in tumorigenesis. Smallmolecules controlling H2A ubiquitination are of interest as potential chemical tools and anticancer drugs. To identify novelsmallmolecule inhibitors of H2A ubiquitination, we synthesized and evaluated several compounds designed based on PRT4165 (), which is a reported histone