The disclosure relates to Compounds of Formulae (IA) and (IB): and pharmaceutically acceptable salts thereof wherein Z1, Z2, Z3, Xa, Xb, Xc, Xd, Y, X2, and X4 are as defined herein, compositions comprising an effective amount of a Compound of Formula (IA) and/or (IB), and methods to treat or prevent a condition, such cancer which overexpresses Her-kinases, comprising administering to an patient in need thereof a therapeutically effective amount of a Compound of Formula (IA) or (IB). The disclosure further relates to compounds of Formulae (IA) and IB) in which X2 is a leaving for introducing a radiolabeled atom, such as 124I or 131I and to methods of using such compounds in the preparation of radiolabeled compounds, particularly for use in imaging.