1. Suggest reagents that would accomplish each of the steps (a) and (d). (2 marks) 
2. Demonstrate your understanding of retrosynthetic analysis by redrawing step (b) in the retrosynthetic direction to show the disconnection of compound 2 and the synthons that correspond to the two reagents. (2 marks) 
3. Propose a mechanism for the Swern Oxidation, step (c). (5 marks)
4. n

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OH b. EtMgBr, THF а. HO. BnO. BnO, H. H. 1 c. DMSO, (COCI)2, Et3N OTES d. BnO, BnO. 3 Et = ethyl (-CH2CH3); Bn = benzyl (-CH2PH); TES = triethylsilyl (-Si(CH2CH3)3) %D TBS = tert-butyldimethylsilyl (-Si((CH3)2C(CH3)3)); DMSO = dimethylsulfoxide %3! 2. OH b. EtMgBr, THF а. HO. BnO. BnO, H. H. 1 c. DMSO, (COCI)2, Et3N OTES d. BnO, BnO. 3 Et = ethyl (-CH2CH3); Bn = benzyl (-CH2PH); TES = triethylsilyl (-Si(CH2CH3)3) %D TBS = tert-butyldimethylsilyl (-Si((CH3)2C(CH3)3)); DMSO = dimethylsulfoxide %3! 2.