['CN', 'CS(=O)(=O)N1CC(NC=O)C1', 'CNC=O', 'CS(=O)(=O)N1CC(N)C1', 'C[SH](=O)=O', 'CNC(=O)NC1CNC1', 'CNC(N)=O', 'CS(=O)(=O)N1CCC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1CNC1.