['CCO', 'O=Cc1nc(-c2cnccn2)no1', 'CC', 'O=C(O)c1nc(-c2cnccn2)no1', 'CCOC=O', 'c1cnc(-c2ncon2)cn1', 'c1cnccn1', 'CCOC(=O)c1ncno1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cnc(-c2ncon2)cn1.