['CN', 'CC1(C)CN(C(=O)CNC=O)CC2(CCCC2)O1', 'CNC=O', 'CC1(C)CN(C(=O)CN)CC2(CCCC2)O1', 'CNC(=O)NCC=O', 'CC1(C)CNCC2(CCCC2)O1', 'CNC(N)=O', 'CC(=O)N1CC(C)(C)OC2(CCCC2)C1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1CCC2(C1)CNCCO2.