Second-generation tricyclic pyrimido-pyrrolo-oxazine mTOR inhibitor with predicted blood–brain barrier permeability† † Electronic supplementary information (ESI) available: Experimental procedures and characterisation for all new compounds. Experimental details and raw data for biological assays, 1H, 13C NMR, HRMS spectra and HPLC chromatograms for all novel compounds. See DOI: 10.1039/d0md00408a