Consider these steps from the recent literature and answer the questions that follow.
i. Briefly explain what is happening at each step (i)–(iv). 2 marks
ii. By considering the acetate (CH3CO), tert-butyldimethylsilyl (TBDMS) and benzyl (Bn or PhCH2) groups used in this example, explain what is meant by an orthogonal protecting group strategy. 2 marks
iii. Propose a mechanism for the transesterification reaction occurring in step (ii). 2 marks
iv. Outline a mechanism to show how dimethylsulfoxide (DMSO) and oxalyl chloride can combine to generate an activated sulfur-centred electrophile, while liberating CO2, CO and chloride ion (the first stage of step (v)). 3 marks
