THEORY:
The Diels-Alder cycloaddition reaction was discovered by Otto Diels and Kurt Alder and is very useful in the synthesis of polycyclic compounds. The Diels-Alder reaction can be described as: [4+2] cycloaddition- a diene with 4 π electrons + 2π electrons from the dienophile; a pericyclic concerted reaction- meaning the reaction occurs in a single step (no intermediates) and involves a cyclic redistribution of bonding electrons.
In order for a Diels-Alder reaction to take place the diene must be a conjugated system oriented in the s-cis conformation; s-trans dienes can undergo the reaction only if there configuration permits free-rotation around one of the –C=C double bonds such that they can assume the s-cis conformation. Diencs locked in the s-cis configuration will react faster than those able to assume both s-cis and s-trans configurations; those locked in the s-trans conformation will not react.
The reaction is favored (proceeds faster) by the......
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