When a new synthesis project is started, there is not yet enough historical data regarding the impurities for that specific drug substance, thus the organic chemistry knowledge of experts plays a central role in enabling structural elucidation from MS/MS. This also poses significant challenges in finetuning our model, as the number of available impurity examples would be too low to allow reliable and generalizable training. To alleviate this "cold start" issue, we attempted to simulate the entire synthesis process of an asset in silico, including impurity formation events. As most impurities arise from known chemical processes, including for example incorrect selectivity and overreactions, we reasoned that it should be possible to reproduce this process given all the starting materials and impurities thereof.