The last reaction step involves an ester amidation reaction between the product of the second reaction step (5b) and 4-fluorobenzylamine (6b). The most nucleophilic site is the primary amine of 6b with a MCA of 489 kJ/mol, and this site is also the proposed reaction center of 6b. The most electrophilic site is the highlighted carbon atom next to the fluorine atom of 6b with a MAA of 310 kJ/mol. The MAA is marked with a star ("*") as the fluorine atom acts as a leaving group during the geometry optimization when attaching the methyl anion to the highlighted carbon atom. The second most electrophilic site is the carbonyl carbon in 5b, which is the other proposed reaction center. This site is marked with a star ("*") as the proton from the phenol group moves to the carbonyl oxygen during the geometry optimization when attaching the methyl anion to the carbonyl carbon. In summary, the use of MCAs and MAAs to flag retrosynthetic steps for further inspection seems promising but will require further work.