['CO', 'Cc1nc(N2CCOCC2)nc(C)c1CC=O', 'C1COCCN1', 'COC(=O)Cc1c(C)ncnc1C', 'COC(C)=O', 'Cc1cc(C)nc(N2CCOCC2)n1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cnc(N2CCOCC2)nc1.