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Question 2 Question 3 (a) Draw the resonance contributors for the following carbocations. [6 marks] OM Mevalonic acid is a precursor in the biosynthetic pathway, referred to as mevalonate pathway that produces steroids and terpenes. Biosynthesis of mevalonic acid is glven below. biological Нас Claisen CH3 COAS C-o condensation Cars Step 1 conser B с + Con cause the (b) Provide detailed mechanisms for the following transformations. [9 marks] 0 Me Step 2 COAS Me -ОН OH Me H2SO4. No Me enantioselective hydrolysis Step 3 OH OH O HO SCOA 3(S) 3 hydroxy-3-methylglutaryl CAA HMO-COA CH compound A (0) Me Me MAMA MGOA Step 4 reductase NH 요 I. Nang ii. H2O (ti) CI NADPH HMG-CoA reductase Step 5 + CO2 compound B OH OH HO OH mevalonic acid (c) Write a detailed mechanism for the given below transformation. Draw the structure of product D. ATP -CO Step 6 1.6 -HO Ph N "YOH Me 1.H2SO4. Compound D ii. H20 Isopentenylpyrophosphate [5 marks] 19 marks (20 marks) (1) Provide detailed mechanisms for steps 1-3. (ii) Define the terms primary and secondary metabolites by giving an example of each. (iii) Draw the structures of compounds A and B. (iv) What is the role of NADPH in step 4. iv) Provide the structure of isopentenyl pyrophosphate, (vi) How many isoprene units are involved in the biosynthesis of camphor (C10H O). [3 marks] [4 marks] [1 mark] [2 marks [1 mark] (20 marks)