Rank 1. Distance of less than 5 corresponds to the synthetically feasible routes that have identical or very similar disconnection strategy to the experimentally described routes. Suggested routes may have less optimal selection of the reactants or protection group strategy, but do not have obvious issues with chemo-or regioselectivity of the key steps. A typical example of the rank 1 route is shown in Figure (molecule 12, distance 1.2). Here, this route and the originally observable route share a very similar disconnection strategy and the key intermediate obtained by two different but equally efficient C-C bond-forming reactions.