Synthesis and Structure–Activity Relationship of Tetra-Substituted Cyclohexyl Diol Inhibitors of Proviral Insertion of Moloney Virus (PIM) Kinases

Overexpression of PIM 1, 2, and 3 kinases is frequently observed in many malignancies. Previously, we discovered a potent and selective pan-PIM kinase inhibitor, compound 2, currently in phase I clinical trials. In this work, we were interested in replacing the amino group on the cyclohexane ring in compound 2 with a hydroxyl group. Structure-based drug design led to cellularly potent but metabolically unstable tetra-substituted cyclohexyl diols. Efforts on the reduction of Log D by introducing polar heterocycles improved metabolic stability. Incorporating fluorine to the tetra-substituted cyclohexyl diol moiety further reduced Log D, resulting in compound 14, a cellularly potent tetra-substituted cyclohexyl diol inhibitor with moderate metabolic stability and good permeability. We also describe the development of efficient and scalable synthetic routes toward synthetically challenging tetra-substituted cyclohexyl diol compounds. In particular, intermediate 36 was identified as a versatile intermediate, enabling a large-scale synthesis of highly substituted cyclohexane derivatives.