['C#CCN', 'Cc1nn(C)c2nc(C(C)C)cc(C=O)c12', 'C#CC', 'Cc1nn(C)c2nc(C(C)C)cc(C(N)=O)c12', 'C#CCNC=O', 'Cc1nn(C)c2nc(C(C)C)ccc12', 'CCC', 'C#CCNC(=O)c1ccnc2c1c(C)nn2C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cnc2[nH]ncc2c1.