4.2 a) b) Explain the purpose of adding then removing the acetal in the synthesis below. Fill in the appropriate reagents. [2] [5] 3 1 2 OEt OEt OEt -OEt EIO HO Eto 4.3 Provide a mechanism for the following transformations. Show all intermediates and use curved arrows to show electron flow. [9] H+ . H2N