2,4,6-Triaminopyrimidine as a Novel Hinge Binder in a Series of PI3Kδ Selective Inhibitors

Inhibition of phosphoinositide 3-kinase delta (PI3K delta) is an appealing target for several hematological malignancies and inflammatory diseases. Herein, we describe the discovery and optimization of a series of propeller shaped PI3K delta inhibitors comprising a novel triaminopyrimidine hinge binder. Combinations of electronic and structural strategies were employed to mitigate aldehyde oxidase mediated metabolism. This medicinal chemistry effort culminated in the identification of 52, a potent and highly selective inhibitor of PI3K delta that demonstrates efficacy in a rat model of arthritis.