['N#CCO', 'O=Cc1ccc2c3c(cccc13)CC2', 'CC#N', 'O=C(O)c1ccc2c3c(cccc13)CC2', 'N#CCOC=O', 'c1cc2c3c(cccc3c1)CC2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cc2c3c(cccc3c1)CC2.