['O=CCCl', 'COc1cccc(NCC(N)=O)c1', 'CO', 'NC(=O)CN(C(=O)CCl)c1ccccc1', 'CC(N)=O', 'COc1cccc(NC(=O)CCl)c1', 'COc1ccccc1', 'NC(=O)CNC(=O)CCl']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.