['CCO', 'O=Cc1cc2cc3ccccc3nc2[nH]1', 'CC', 'O=C(O)c1cc2cc3ccccc3nc2[nH]1', 'CCOC=O', 'c1ccc2nc3[nH]ccc3cc2c1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2nc3[nH]ccc3cc2c1.