['CN(C)C(C)(C)C', 'Cc1cc(N)n2nc(C(F)(F)F)nc2n1', 'CNC', 'Cc1cc(NCC(C)C)n2nc(C(F)(F)F)nc2n1', 'CN(C)C(C)(C)CN', 'Cc1ccn2nc(C(F)(F)F)nc2n1', 'FC(F)F', 'Cc1cc(NCC(C)(C)N(C)C)n2ncnc2n1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cnc2ncnn2c1.