A series of 32 derivatives and isosteres of the mTOR inhibitor 2 were synthesized and compared for their cytotoxicity in radioresistant SQ20B cancer cell line. Several of these compounds, in particular 30b, were significantly more cytotoxic than 2. Importantly, 30b was shown to block both mTORC1 and Akt signaling, suggesting insensitivity to the resistance associated to Akt overactivation observed with rapamycin derivatives currently used in clinic.