Compounds of formula I, and pharmaceutically acceptable salts thereof are described, as well as the pharmaceutical compositions containing said compounds and their pharmaceutically acceptable salts, and the use of said compounds and pharmaceutical compositions for the treatment, control or amelioration of proliferative diseases, including cancer, Down syndrome or early onset Alzheimer's disease.L'invention concerne des composés de formule I, et des sels pharmaceutiquement acceptables de ceux-ci, ainsi que les compositions pharmaceutiques contenant lesdits composés et leurs sels pharmaceutiquement acceptables, et l'utilisation desdits composés et compositions pharmaceutiques pour le traitement, la gestion ou l'amélioration de maladies prolifératives, notamment le cancer, le syndrome de Down ou la maladie d'Alzheimer à apparition précoce.