['CO', 'CCN(CCOC)Cc1nnc(C2CC2)o1', 'CCOC', 'COCCNCc1nnc(C2CC2)o1', 'Cc1nnc(C2CC2)o1', 'COCCNCCOC', 'c1nnc(C2CC2)o1', 'COCCN(C)CCOC', 'C1CC1', 'COCCN(CCOC)Cc1nnco1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1nnc(C2CC2)o1.