Aurora B plays critical role in the process of chromosome condensation and chromosome orientation during the regulation of mitosis. The overexpression of Aurora B has been observed in several tumor types. As a part of our ongoing effort to develop Aurora B inhibitors, herein, we described the design, synthesis and evaluation of phenyl/pyridine diazepine analogs. The diazepane aniline pyrimidine (4a) was identified as an initial hit (Aurora B IC50 6.9µM). Molecular modeling guided SAR optimization lead to the identification of 8-fluorobenzodiazepine (6c) with single digit nM potency (Aurora B IC50 8nM). In the antiproliferation assay 6c showed activity across the cell lines with IC50 of 0.57, 0.42, and 0.69µM for MCF-7, MDA-MB 231, and SkoV3 respectively. In the in vivo PK profile. 6c has shown higher bioavailability (73%) along with good exposure (AUC of 1360ng.h/mL).