0244Pb20an-10.cwk (WP)

0244Pb20an-10.cwk - reaction makes the product 5 We know the reaction is concerted and therefore that the stereochemistry of the product is as

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Answers to Problem 20, Chemistry 0244 - 2010 H 3 C H 3 C 4 CN NC heat + CH 3 CN CN CH 3 5 H 3 C H 3 C Con-R heat heat + First of all, compound 4 decomposes in a reverse Diels-Alder reaction to give benzene and 3,4-dimethylcyclobutene. The cyclobutene opens in conrotatory fashion to give cis,trans-2,4-hexadiene. Why that stereochemistry? It is a four-electron system, and so the thermal interconversion of cyclobutene and butadiene is Con-R. Now a Diels-Alder
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Unformatted text preview: reaction makes the product, 5 . We know the reaction is concerted, and therefore that the stereochemistry of the product is as shown, because there is a bonding match between HOMO and LUMO. Con-R HOMO CH 3 CH 3 H 3 C CH 3 cis heat CN NC LUMO CH 3 CN CN CH 3 heat 5...
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This note was uploaded on 03/02/2010 for the course CHEM orgo taught by Professor Jones during the Spring '10 term at NYU.

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