The subject invention concerns materials and methods for inhibiting the Akt/PKB pathway. In one embodiment, a compound of the invention inhibits kinase activity and/or phosphorylation levels of Akt proteins. The subject invention also concerns methods for inhibiting or killing a cancer cell or other cell in which expression of an Akt protein is elevated or constitutively active, comprising contacting the cell with an effective amount of a compound of formula I. The subject invention also concerns methods for treating cancer or a tumor in a person or animal comprising administering an effective amount of a compound of formula I to the person or animal.