Chem 353-27

Chem 353-27 - 5 The customary laboratory source of...

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Post Lab Questions – Diels-Alder (You may write the answers only in your notebook for the post lab questions if you choose.) 1. Predict the structure of the product in the following Diels-Alder reaction. 2. Predict the structure of the diene and the dienophile that would lead to the following product. 3. Draw two structures for the product of question #1 that clearly demonstrate that the diastereotopic hydrogens are not equivalent using deuterium to substitute for the appropriate hydrogens. Label all the stereogenic centers in both structures as either R or S. Do R and S labels at the stereogenic centers always help confirm diastereotopicity? 4. Consider the product of question #1 and the product of your experiment. Both structures have two new stereogenic centers, yet neither forms a racemic mixture, nor are the products optically active. Explain why this is the case.
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Unformatted text preview: 5. The customary laboratory source of 1,3-cyclopentaldiene is a compound called “dicyclopentadiene” (C 10 H 12 ). Dicyclopentadiene is the Diels-Alder cycloaddition of two molecules of 1,3-cyclopentadiene. One molecule acts as a diene, the other as a dienophile. Heating dicyclopentadiene causes it to undergo a retro Diels-Alder reaction to give 1,3-cyclopentadieane analogous to how 3-sulfolene give s-cis-1,3-butadiene upon heating as with your experiment. Using the proton spectrum for dicyclopentadiene below (left) deduce the correct structure from the choices below (A-D). 6. Give the mechanism for the reaction below. 7. Explain why there is only one possible answer for question #5 using the frontier molecular orbitals (HOMO and LUMO) of cyclopentadiene shown below (right). Anti bonding and bonding orbitals of the π system of cyclopentadiene....
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This note was uploaded on 04/06/2011 for the course CHEM 353 taught by Professor Bronson during the Winter '11 term at BYU.

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