['CC(C)(C)N', 'O=CN1CC2(CCC2)C1C1CCCO1', 'CC(C)(C)NC=O', 'C1COC(C2NCC23CCC3)C1', 'CC(C)C', 'NC(=O)N1CC2(CCC2)C1C1CCCO1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1COC(C2NCC23CCC3)C1.