['CN', 'COc1cc2c(cc1OC)CCN(CC=O)CC2', 'CO', 'CNC(=O)CN1CCc2ccc(OC)cc2CC1', 'CNC(C)=O', 'COc1cc2c(cc1OC)CCNCC2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2c(c1)CCNCC2.