['NC(=O)C(N)C(N)=O', 'CC(C)(C)Cc1noc2ncc(C=O)cc12', 'NC(=O)CC(N)=O', 'CC(C)(C)Cc1noc2ncc(C(N)=O)cc12', 'NC(=O)C(NC=O)C(N)=O', 'CC(C)(C)Cc1noc2ncccc12', 'CC(C)(C)C', 'NC(=O)C(NC(=O)c1cnc2oncc2c1)C(N)=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cnc2oncc2c1.