Pyrazolo[1,5-a]pyrimidines as estrogen receptor ligands: defining the orientation of a novel heterocyclic core

We have examined the pyrazolo[1,5-a]pyrimidine scaffold as a novel core structure for estrogen receptor ligands. Attachment of various substituents has helped to define the orientation of this heterocycle in the ligand-binding pocket as one in which a pendant phenol rather than the hydroxylpyrimidine serves as a mimic of the A-ring of estradiol.