['COCCOCC=O', 'C[C@H](N)c1cc2ccccc2o1', 'CO', 'CCOCC(=O)N[C@@H](C)c1cc2ccccc2o1', 'CCOC', 'C[C@H](NC(=O)CO)c1cc2ccccc2o1', 'COCCO', 'CC(=O)N[C@@H](C)c1cc2ccccc2o1', 'COCCOCC(N)=O', 'CCc1cc2ccccc2o1', 'c1ccc2occc2c1', 'CCNC(=O)COCCOC']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2occc2c1.