Which of the given will facilitate a normal Diels–Alder reaction?

a. an electron donating group on the reaction solvent molecule
b. an electron withdrawing group on the diene and the dienophile
c. an electron withdrawing group on the diene
d. an electron withdrawing group on the dienophile

D

Explanation:

-  The rate of the Diels-Alder is orders of magnitude faster if there is an electron-withdrawing group on the dienophile. For example, replacing a hydrogen on ethene with the electron-withdrawing group CN results in about a 10^5 increase in the reaction rate.

- Other common electron withdrawing functional groups that will accelerate the Diels Alder reaction of dienophiles include aldehydes, ketones, and esters.

- In short, any functional group conjugated with the pi bond which can act as a pi acceptor will accelerate a Diels-Alder reaction with a typical diene.

- See attachment for graphical explanation.

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