['CO', 'O=CCCCCCNC(=O)c1ccc2c(c1)C(=O)c1ccccc1-2', 'COC(=O)CCCCCN', 'O=Cc1ccc2c(c1)C(=O)c1ccccc1-2', 'CCCCCC(=O)OC', 'NC(=O)c1ccc2c(c1)C(=O)c1ccccc1-2', 'COC(=O)CCCCCNC=O', 'O=C1c2ccccc2-c2ccccc21']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1c2ccccc2-c2ccccc21.