['CCC=O', 'NCCNC(=O)c1ccc(Cl)cc1', 'CCC(=O)NCCN', 'O=Cc1ccc(Cl)cc1', 'CCC(N)=O', 'CCNC(=O)c1ccc(Cl)cc1', 'CCNC(=O)CC', 'NC(=O)c1ccc(Cl)cc1', 'Clc1ccccc1', 'CCC(=O)NCCNC=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.