['COCCN', 'O=CCCNCc1ccc2ccccc2c1', 'CO', 'CCNC(=O)CCNCc1ccc2ccccc2c1', 'CCOC', 'NC(=O)CCNCc1ccc2ccccc2c1', 'CCC(=O)NCCOC', 'NCc1ccc2ccccc2c1', 'COCCNC(=O)CCN', 'Cc1ccc2ccccc2c1', 'c1ccc2ccccc2c1', 'CNCCC(=O)NCCOC']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2ccccc2c1.