['CC(C)C=O', 'NCCNC(=O)c1ccnc(Cl)c1', 'O=Cc1ccnc(Cl)c1', 'CC(C)C(=O)NCCN', 'CC(C)C(N)=O', 'CCNC(=O)c1ccnc(Cl)c1', 'CCNC(=O)C(C)C', 'NC(=O)c1ccnc(Cl)c1', 'Clc1ccccn1', 'CC(C)C(=O)NCCNC=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccncc1.