['CC(C)(C)NCC=O', 'NC1CCc2ccccc21', 'CC(C)C', 'NCC(=O)NC1CCc2ccccc21', 'CC(C)(C)N', 'CC(=O)NC1CCc2ccccc21']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2c(c1)CCC2.