The development of the techniques underlying MolTrans has been continued in the IBM RXN for Chemistry (IBM RXN) package, 22 so this is the package we compare to Re-gioSQM20. We use N-bromosuccinimide (NBS) as the reagent since this is the source of Br for most of the reactions in our data set and, as before, we use the tautomeric form found in the data set. With IBM RXN we only have access to the most likely prediction and with this limitation the success rate is 76.3% using the entire data set. This is somewhat lower than the top-1 success rate of 83% reported for MolTrans by Schwaller et al. for a different data set. It is not clear whether the difference is due to differences in the data set or differences between MolTrans and IBM RXN. However, the corresponding success rate for the 426 molecules with only one unique experimentally observed reaction site and where RegioSQM20* only predicts one unique (green) reactive site is 85.0%, which is closer to the value reported by Schwaller et al. and somewhat lower than the 96.0% and 92.0% observed for WLN and RegioSQM20*.