Finally, we can ask if a transformation significantly increases the size of the accessible chemical space. In we have shown that addition of a single key transformation can dramatically increase the number of synthesis route options. Clearly, such a transformation could be a highly valuable target to pursue. Here the insertion of a nitrogen atom between benzene ring and carbonyl group (though in some cases a further transformation is required to obtain a carbonyl group) is a transformation that is repeatedly found (c.f. ranks 8, 26, 44, and 48) and would result in 74 additional routes of interest , rendering it a potential target for closer investigation.