['COCC=O', 'NC1CC1c1ccccc1', 'CO', 'CC(=O)NC1CC1c1ccccc1', 'COCC(N)=O', 'c1ccc(C2CC2)cc1', 'c1ccccc1', 'COCC(=O)NC1CC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(C2CC2)cc1.