2007_Exam_2 - membered ring product. Explain (concisely!)...

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2nd Hour Exam Organic Chemistry c3046y Monday, Mar. 5, 2007 Prof. Leighton The exam is 5 pages long ( not including this one). Please make sure you have all of the pages. . . Question 1 (25 pts): Question 2 (20 pts): Question 3 (20 pts): Question 4 (15 pts): Name: ID#__________________________ Write your name on every page. . Question 5 (20 pts): Total (100 pts):____________ Signature:__________________________ Write complete but succinct answers. Good Luck!
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Name: Page 1 1. Provide a detailed mechanism to account for the following transformations. a. (15 pts) b. (10 pts) H + N Ar Me O N Me Ar + O Me Ph OH O O Δ Ph O H + CO 2
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Page 2 Name: 2. (20 pts) Show how a double Mannich reaction could be used to synthesize the illustrated target. You should clearly indicate the required starting materials, and show how the reactions proceed. You do not need to show a detailed mechanism, but you should show the key intermediates. N Me O H + Target Starting Materials
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Name: Page 3 b. (5 pts) Normally, one would expect the 6-membered ring starting material to be more stable than the 9-
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Unformatted text preview: membered ring product. Explain (concisely!) why this reaction proceeds the way it does to give the presumably less stable 9-membered ring product. 3. a. (15 pts) Provide a mechanism for the following reaction. Me O O O OEt O OEt O Me O 1. NaOEt, EtOH 2. H 3 O + (Quench) Name: Page 4 4. (15 pts) In 1965 E. J. Corey and coworkers published the total synthesis of helminthosporal. Compound A was an intermediate in the synthesis and can be converted into the natural product in just 3 steps. Describe the 3 steps needed to carry out this transformation. You do not need to draw detailed mechanisms, but clearly indicate what each step is doing, and what the product of each step is. CHO Me i-Pr Me O H Helminthosporal Me-Pr O O Me A 3 Steps Name: Page 5 5. (20 pts) For the reaction shown below, predict the product and provide a mechanism for its formation. O OH H 2 O...
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This note was uploaded on 04/16/2008 for the course CHEM C3046 taught by Professor Leighton during the Spring '08 term at Columbia.

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2007_Exam_2 - membered ring product. Explain (concisely!)...

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