['CCC', 'OCCNCc1nnc(C2CC2)o1', 'CCO', 'CCCNCc1nnc(C2CC2)o1', 'CCCNCCO', 'Cc1nnc(C2CC2)o1', 'CCCN(C)CCO', 'c1nnc(C2CC2)o1', 'C1CC1', 'CCCN(CCO)Cc1nnco1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1nnc(C2CC2)o1.