The performance of the model on ring systems classed as 'rare' in the ZINC database, is surprising (Figure ). These rings systems can be assumed to be difficult to access synthetically, yet the model is able to predict a one-step retrosynthetic disconnection in most cases. Examples are shown in Figure , with their corresponding patent precedent, which refers to the patent containing the reaction from which the predicted template was extracted. Whilst the retrosynthetic disconnection may not be used as described in the forward sense, we show that 'Ring Breaker' can act as an idea generator from which a trained synthetic chemist can build upon. model, trained on the USPTO or Reaxys data. The templates must be specific enough to yield a substructure match to the compound they are applied to and produce feasible reactants, whilst being general enough to be applicable across a broad range of suitable compounds without being promiscuous. Balancing these two requirements means that in cases such as the furan synthesis, the template predicted for more complex ring systems cannot be applied to the simple ring system shown. c) Predicted retrosynthetic disconnections using the USPTO 'Ring Breaker' are shown for a selection of compounds in the rare subset. For each prediction, the patent id corresponding to the template used has been given as a precedent.