Diels–Alder Reaction

Diels–Alder Reaction - DielsAlder Reaction...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Chaper 15 1 Diels–Alder Reaction Named after Otto Diels and Kurt Alder. They received the Nobel prize in1950. Produces a cyclohexene ring. The reaction is between a diene with an electron-deficient alkene (dienophile) . The Diels-Alder is also called a [4+2] cycloaddition because a ring is formed by the interaction of four pi electrons of the alkene with two pi electrons of the alkene or alkyne.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The Diels–Alder Reaction: A 1,4-Addition Reaction The Diels–Alder reaction is a pericyclic reaction; a [4+2] cycloaddition reaction All bond making and breaking happens at once: 3 π -bonds break 2 σ -bonds and 1 π -bond form
Background image of page 2
s-cis diene conformational requirement The diene must be in the s -cis conformation to react The diene must be locked or be able to single-bond rotate it’s way into the “s-cis” conformation in order to react Cyclic dienes which are in the s-cis conformation are highly reactive
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chaper 15 4 S -Cis Conformation of the Diene The s -cis conformation can rotate around the C—C single bond to get the more stable s -trans conformation. The s -trans conformation is 12 kJ/mol more stable than the s -cis. H H H H H H s -trans s -cis H H H H H H
Background image of page 4
The diene must be in the s -cis conformation to react, Why? s- Trans: Confirmation would lead to formation of a highly unstable trans bond in a 6-membered ring.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Diels-Alder Rate for Dienes When the diene is sterically hindered, the reaction slows down even though the conformation can be s-cis .
Background image of page 6
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 33

Diels–Alder Reaction - DielsAlder Reaction...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online