['CN', 'O=CCSc1nnc(N2CCNCC2)s1', 'CNC(C)=O', 'Sc1nnc(N2CCNCC2)s1', 'C1CNCCN1', 'CNC(=O)CSc1nncs1', 'CNC(=O)CS', 'c1nnc(N2CCNCC2)s1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1nnc(N2CCNCC2)s1.