['CC1(C)C[C@@H]1C=O', 'NC1CC12CCCC2', 'C1CCC2(C1)CC2', 'CC1(C)C[C@@H]1C(N)=O', 'CC1(C)CC1', 'O=CNC1CC12CCCC2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(NC1CC12CCCC2)C1CC1.