['COCC=O', 'CCCCC1CCC(N)CC1', 'CO', 'CCCCC1CCC(NC(C)=O)CC1', 'COCC(N)=O', 'CCCCC1CCCCC1', 'CCCC', 'COCC(=O)NC1CCCCC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1CCCCC1.