POD11Key - as only sources of carbon atoms H O OH O and Br...

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Problem of the Day #11 – Answer Key Deadline : IN CLASS on Th 7/29/2010 LATE WORK WILL NOT BE ACCEPTED OR GRADED!!! This problem is worth a total of 20 raw points. In each part below, propose a sequence of reactions to synthesize the target compound from the indicated starting material(s). You may use any other organic and/or inorganic reagents necessary to complete your synthesis, but all carbon atoms in the target must be derived from the starting material(s) specified in each part. It is only necessary to give overall transformations in answering this question. It is not necessary to provide complete curved arrow mechanisms for the reactions that you use. Use the back of the page if you need more space for your answers. (b) (12 points) Prepare (target, as a racemic mixture) from
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Unformatted text preview: as only sources of carbon atoms H O OH O and Br and CH 3 I (a) (8 points) Prepare (target, as a racemic mixture) from and as only sources of carbon atoms OH O OH Br O CO 2 Br O O H OH H 2 SO 4 (cat.) Br O O Mg MgBr O O 1) CO 2 2) H 3 O + OH O O NaBH 4 in CH 3 OH OH O OH (racemic) The ketone must be protected before preparation of the Grignard reagent. A Gringard reagent would react with an unprotected ketone!!! The acetal protecting group will be hydrolyzed upon the acid workup to yield the deprotected ketone Only the ketone will be reduced if NaBH 4 is used. LiAlH 4 would also reduce the carboxylic acid!!! Mg H O OH O Br CH 3 I MgBr 1) PPh 3 2) BuLi H 2 C PPh 3 2) H 3 O + MgBr 1) OH H 2 CrO 4 O H 2 C PPh 3 1) BH 3 2) H 2 O 2 , NaOH, H 2 O OH H 2 CrO 4...
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This note was uploaded on 10/25/2010 for the course CH 310n taught by Professor Iverson during the Summer '08 term at University of Texas.

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