DielsAlder-Report - Diels-Alder cycloadditionbetweena...

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Diels-Alder Itrtroduction: The Diels-Alder reaction is a stereospecific cycloaddition between a diene and a diemphile. This rcaction is also pedcyclic, meaning tbat it's concerted and only involves a single cyclic intermediate in which bonds aIe simultaneously being formed and broken. ln order fo. such a cyclic intermediate to form, the diene must be both conjugated and in the cis conformation. Dienedienophile pairs are €sp€cially effective reagents and therefore shift the reaction in favor ofthe product, when their electron distibutions differ as occurs when electon-withdrawing substitueots ar€ incorpomted in the dienophile' Although the Diels-Alder r€action is stercospecific, endo and exo diastereomers can form wten one or both ofthe reagents is a cyclic molecute. A bridge is formed in the adduct and in -.- --. . : .r. __!: tlte endo product this bridge is on the same side ofthe molecule as the hydrrogen atoms at either ' side ofwhat was previously the catbon-carbon double bond ofthe dienophile' The exo product is then the reverse. in which these hydrogens are on the opposite side ofthe molecule as the bridge., .l --.l ,^'.-rI'! \{. .t 1. ,-Y./, i In this lab, strictly the Q-c-pheltandrene isorlrcr is used so that strictly the endo adduct .\ will be synthesized.)The endo product is usually fg{ored in Diels-Alder rcactions because lhe
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This note was uploaded on 09/09/2008 for the course CHEM 245 taught by Professor Burdette during the Spring '08 term at UConn.

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DielsAlder-Report - Diels-Alder cycloadditionbetweena...

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