['CN', 'O=CNC(=O)CN1CCCc2cc(F)c(F)cc21', 'CNC=O', 'NC(=O)CN1CCCc2cc(F)c(F)cc21', 'CNC(N)=O', 'O=CCN1CCCc2cc(F)c(F)cc21', 'CNC(=O)NC(C)=O', 'Fc1cc2c(cc1F)NCCC2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2c(c1)CCCN2.