['CCCC=O', 'Cc1ccc(C(=O)NCCN)cc1F', 'CCCC(=O)NCCN', 'Cc1ccc(C=O)cc1F', 'CCCC(N)=O', 'CCNC(=O)c1ccc(C)c(F)c1', 'CCCC(=O)NCC', 'Cc1ccc(C(N)=O)cc1F', 'Cc1ccccc1F', 'CCCC(=O)NCCNC=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.