Q2, Part ii)

Part iii)

Give reagents K, L, M, N and P needed for the following transformations. OH L -CO_CH3 COCH3 N III CO2CH2CH3 CH3 CH3 COH Br OMe Bno Bno Bno Bno "OH OBn OBn [30 marks] (iii) Answer either part (a) or part (b) (a) The reduction of an alkyne can be carried out using Na and liquid NH3. Write a mechanism for this reaction that accounts for the stereochemical outcome. [20 marks] (b) The reaction of Q with LiAlH4 followed by work-up with H20 gives R. If the work up was done with D20 (D = deuterium) rather than H20, then I was obtained. If LiAlD4 was used followed by work-up with H20 then S was obtained. Suggest a mechanism that is consistent with the data given. What type(s) of selectivity are observed in this reaction? Briefly explain your answer. H . 1. LIAIHA 2. Work-up with H2O Quia OH RH 1. LIAIDA 2. Work-up with H2O 1. LIAIHA 2. Work-up with D20 H OH OH D HS T [20 marks]