pset8 - Massachusetts Institute of Technology 5.13 Fall...

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Unformatted text preview: Massachusetts Institute of Technology 5.13, Fall 2006 Problem Set #8 Due: December 4, 2006, 12:00 PM 1. Propose a one-step synthesis for the following compounds using the Robinson annulation. Me OCH3 a) O O b) CO 2Et 2. Write the products for the following reactions. O a) CH 3 H2C NaOCH3 CH3OH, D O O 1. LDA b) 2. HC CH 3 O 3. Identify the intermediates A and B in the transformation below and show how they are formed (mechanism). CH3 O H CH3 O EtO H excess NaOEt O KOtBu A Et B -OH H2O H3 C H O 1 Massachusetts Institute of Technology 5.13, Fall 2006 4. Write reagents (a, b, c, d) where they have been omitted from the following synthetic sequence. Each letter may correspond to one or more reaction steops. This sequence is the beginning of a synthesis of germanicol, a naturally occurring triterpene. Me Me H Me Me H HO Me Me H Me Me Germanicol a O Me H3C Me H3 C O O O O CH 3 H+, ethylene glycol O O b Me Me O Me H O O c O O H Me M e Me H Me Me Me Me H O 1. Li, NH3 2. CH3I O O H Me M e 2 Me O Me d O Me O O Massachusetts Institute of Technology 5.13, Fall 2006 5. Provide a mechanism for each of the following transformations. O O NaOMe (1 eq.) O a) Ph M eOH O Ph H N b) Me Me N N cat. H+ N O Me Me 6. Provide a synthesis for each of the following products. O O a) Me O H Ph O c) b) Me N H Me MeO H EtOH OH starting materials 3 Me PrOH OH Ph O O d) Ph Me ...
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This note was uploaded on 11/27/2011 for the course CHEMICAL E 20.410j taught by Professor Rogerd.kamm during the Spring '03 term at MIT.

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