['NC(=O)CO', 'O=Cc1cc2ccccc2c2cccnc12', 'CC(N)=O', 'O=C(O)c1cc2ccccc2c2cccnc12', 'NC(=O)COC=O', 'c1ccc2c(c1)ccc1ncccc12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2c(c1)ccc1ncccc12.