['NCCNCCO', 'Cc1ccc2c(c1)n(C)c(=O)n2C', 'CCNCCO', 'Cn1c(=O)n(C)c2cc(CN)ccc21', 'NCCO', 'CCNCc1ccc2c(c1)n(C)c(=O)n2C', 'CCO', 'Cn1c(=O)n(C)c2cc(CNCCN)ccc21', 'CNCCNCCO', 'Cn1c(=O)n(C)c2ccccc21']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1[nH]c2ccccc2[nH]1.