Dienophile and diene help? organic chemistry

[bonfire09]

dienophile and diene help?? organic chemistry

We never really covered how to do diels alder reactions and I am having trouble how
to do these. Here is a photo of the lab page with the questions. I just need help
with 2a-e and 3b-3d. Thanks.

 

[Borek]

http://en.wikipedia.org/wiki/Diels–Alder_reaction

 

[bonfire09]

Wikipedia doesn't help tried that already.

 

[Borek]

Diels-Alder reaction is between two specific structural elements, can you name them? Can you locate them in the compounds listed in the book? It is pretty straightforward.

 

[chemisttree]

Start with 2a, can you identify the diene?

 

[bonfire09]

yeah the diene and dienophile.

2a the diene is the double bonded hexyl groups. The dienophile is the two bonded COOCH3 groups.

2b. the diene is the cyclehexen-1,3-diene. the dienophile is the 1,2-chlorohexene

2c. the diene is cyclopenten-1,3-diene. the dienophile is the second one. barely learning to naming those. I know its an ester group.

2d. the diene is the cyclopenten-1,3-diene. the dienophile is the prop-1-en-2-ol

2e. the diene is the alkene(2nd compound) and the dienophile is the cyclopentene with the chlorides surrounding it.

 

[bonfire09]

here are my answers

2a.

 

[Borek]

Close to correct, but you need to think about stereochemistry. Are -COOCH₃ on the same side of the ring (they don't lie on the paper surface)?

 

[bonfire09]

oh its both stereocenters so one will have a wedge while the other will have dashed lines

 

[bonfire09]

so something like this?

 

[bonfire09]

here is my answer for 2b,2c,2d

 

[bonfire09]

and 2e.

 

[Borek]

2a looks OK to me. Other products will be polycyclic. Dienophile and diene create a new ring (dienophile "closes" the diene).

 

[bonfire09]

so the rest are wrong then? ok ill try to figure them out then