The present invention is directed to compounds having the Formulae (Ia-Ie), (II), (IIIa-IIId), (IVa-IVc), (Va-Vb), (VIa-VIe), (VII), (VIIIa-VIIIc), and (IX), pharmaceutically acceptable salts, prodrugs and solvates thereof, compositions of any of thereof and methods for the treatment of a condition associated with a dysfunction in proteostasis comprising an effective amount of these compounds.
