a) Compound 5 was used as a lead compound in the development of inhibitors of an enzyme. Analogues 6-8 were synthesised and their IC50 values were determined with in vitro assays using the isolated enzyme. (ii) For each of the analogues 6-8, give a possible explanation of their change in potency compared to the lead compound 5. [6 marks] (iii) For each of the analogues 6-8, name the optimisation strategy used for their design. [3 marks]