['CC(C)NC(C)C', 'O=CCn1ccc2ccccc21', 'CCC', 'CC(C)NC(=O)Cn1ccc2ccccc21', 'c1ccc2[nH]ccc2c1', 'CC(=O)N(C(C)C)C(C)C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2[nH]ccc2c1.