['NC(=O)C1CCNCC1', 'CCc1nc(C#N)co1', 'NC=O', 'CCc1nc(C#N)c(N2CCCCC2)o1', 'CC', 'N#Cc1ncoc1N1CCC(C(N)=O)CC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ncc(N2CCCCC2)o1.