['CO', 'CN(C)c1c(C(=O)O)cnc2ccccc12', 'CNC', 'COc1cccc2cc(C(=O)O)cnc12', 'O=CO', 'COc1cccc2c(N(C)C)ccnc12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2ncccc2c1.