Week_3.3_PurpleBook_Answers

Week_3.3_PurpleBook_Answers - 71 Making Alcohols into...

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OH Cl OH Cl OH OH Making Alcohols into Leaving Groups 1. The OH from an alcohol is not a good leaving group. Why? One way of making it a good leaving group is to protonate it. This often creates problems with carbocations, rearrangements, etc. It can be used in limited cases: 2. Provide curved-arrow mechanisms for the following transformations: The best ways of turning alcohols into leaving groups (at least for S N 2 reactions) are to use either SOCl 2 or to form a "tosylate": 3. Provide the intermediates and products in the following synthetic sequences. Watch stereochemistry ! SOCl 2 , pyridine OH 2 TsCl, pyridine OH 2 OH is a very strong base and strong bases make poor leaving groups. + + Cl OTs CN CN + HCl HCl NaCN NaCN H + :Cl H + SN1 SN2 Cl: Week 3 71
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OH Cl OTs Br S Cl O O CH 3 R O 2 S Cl O S H O O R O S O O R S Cl O Cl OH OH O S H O Cl O S O Cl Making Alcohols into Leaving Groups: Mechanisms 1. Provide a complete curved-arrow mechanism for each of the following transformations. Be sure to pay attention to stereochemistry! P
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This note was uploaded on 05/01/2008 for the course CHEM 51 taught by Professor Gribble during the Spring '08 term at Dartmouth.

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Week_3.3_PurpleBook_Answers - 71 Making Alcohols into...

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