['NC=O', 'NC(=O)CCN1CCCc2cc(F)ccc21', 'NC(N)=O', 'O=CCCN1CCCc2cc(F)ccc21', 'CCC(=O)NC(N)=O', 'Fc1ccc2c(c1)CCCN2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2c(c1)CCCN2.