Weekly Review 5 (Key)

Weekly Review 5 (Key) - Chem S 20ab Part III: Synthesis 2)...

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Review 5 Weekly Review Answers Chem S 20ab 1. In molecule 1, the N lone pair, a good donor orbital, is aligned as shown with the * CCl orbital, a good acceptor. This overlap shortens and strengthens the C-N bond, while it lengthens and weakens the C-Cl bond. In molecule 2, there is no overlap between the N lone pair and the * CCl orbital, so there is no strengthening of the C-N bond. Therefore, the C-N bond is stronger in molecule 1 than it is in molecule 2. Stronger bonds have higher IR stretching frequencies. N Cl OH N Cl HO C-Cl C-Cl 2. a.
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Review 5 Weekly Review Answers Chem S 20ab This route will NOT work, because the Claisen condensation is reversible, and will only be driven to completion if the beta-dicarbonyl product can be deprotonated between the carbonyls. In this case, there is no proton between the carbonyls, so the reaction will favor the starting material. b.
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Review 5 Weekly Review Answers
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Unformatted text preview: Chem S 20ab Part III: Synthesis 2) Provide a complete synthetic route from the given starting material to the indicated product. Unless otherwise indicated, you may use any organic or inorganic reagents. a. b. O O OEt O OEt O NaOEt Br Br NaOEt O OEt O 1) NaOH 2) H 3 O + , heat c. 1 ) N a O E t 2 H + w k u p , Review 5 Weekly Review Answers Chem S 20ab d. e. f. O O H O NaOMe O 1 ) O 3 2 M e S O CuLi 1) 2) H + wkup H O O NaOMe Review 5 Weekly Review Answers Chem S 20ab g. O EtO 2 C Et NaOEt O O EtO 2 C Et NaOEt O Et OEt O O (Michael addition) (aldol condensation) O Et EtO O OEt (making beta dicarbonyl to use as Michael addition nucleophile) O Et 2 CuLi (cuprate conj. addition) 1) O 3 2) Me 2 S H O O NaOMe (aldol condensation) Review 5 Weekly Review Answers Chem S 20ab h. O O N B r 2 , H + O Br N a C i....
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This note was uploaded on 01/22/2012 for the course CHEM CHEM E-2B taught by Professor Loganmccarty during the Summer '09 term at Harvard.

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Weekly Review 5 (Key) - Chem S 20ab Part III: Synthesis 2)...

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