In continuation of the effort in the synthesis of novel oxadiazoles [22,23,24,25,26,27,28], herein synthesis of oxadiazoles with substitutions of pyridine, biphenyl, pyrimidine, and thiophene rings that target PARP1 and the efficacy of these compounds in BRCA wild-type estrogen receptor positive (ER+) and triple-negative breast cancer (TNBC) cells is reported. Here, ESR1 is linked to triple-negative breast carcinoma.