[kidd101]

Hi,
I'm having problem writing organic product(s) of a rxn. all the sn1, sn2, e1, e2 is confusing me.
I have this homework assignment and could use some help. I have written the products and i would like u to tell me if it is current or incorrect. If it is wrong, could u briefly explain why it is wrong.



thank u,
e

[azmanam]

all ok except 4.  check stereochem (although if you want to tick your prof off, write no rxn - at least after quench... j/k)

edit.  ignore.  it is a sack of raving nonsense

[Dan]

Looks ok to me, although I think Q4 may be more complicated than you think. I think your relative stereochemistry of the OH groups in the product is absolutely correct though.

Are you given the stereochemistry of the other two stereogenic centres in the starting material - ie. is it a cis or a trans decalin? I ask because this one isn't a simple S_N2, and could give a mixture of products. Whether it is a cis or trans decalin is going to affect your product distribution.

[azmanam]

Looks ok to me, although I think Q4 may be more complicated than you think

Dans absolutely right.  follow his advice, not mine. I was looking at it wrong at first. Ignore my entire comment completely.  Forget it ever happened.

[orgopete]

For Q3, I have 2x CH3I.

For Q4, I have the epoxide. I suppose you could get it to open if you were trying. If not, it is going to give you the epoxide. (I think that is an org syn prep.) The epoxide formation will be fast and opening slow.

[kidd101]

@ Dan
No she hasn't given us any stereochemistry for the other two stereogenic centres.
@ azmanam
Yup the first reply never happened, but thx for the help.
@ orgopete
She said the reaction is balanced n therefore i'm starting with only one idodide.

Now i'm even more confused on Q4. is it suppose to open up? if it is could u guide me b/c i don't see how it is suppose to open up.

I have a question
CH2=CH-CH=CH2  +  H2O   ----->(H+ catalyst)  will it form
                                                CH3-CH2-CH=CH2  +  CH3-CH=CH-CH3

If it is wrong then am i suppose to attach hydroxide ion to one of the product group?

thank u for the help so far.

[Dan]

OK, I might be overthinking here but here goes...

I would have thought the epoxide formed would be opened to the diol. Ring opening of epoxides on 6-membered rings is usually in accordance with the Furst-Plattner rule (trans-diaxial ring opening).

In the case of a trans decalin, the structure of the ring system is fixed (no ring flipping) and as such we would predict one major diastereoisomer (the one you drew) and maybe some of the minor diasteroisomer (shown in red).

On the other hand, a cis decalin is more flexible. Equilibrium between the two conformations I have show (which are conformational enantiomers), allows trans-diaxial ring opening to either enantiomer of the diol product with equal probability - racemic mixture

[azmanam]

I think you overthought it.  I'm fairly confident the epoxide will be the product.

http://www.cem.msu.edu/~reusch/VirtTxtJml/addene1.htm#add3b (bottom)

[kidd101]

Thanks dan and azmanam. I had to turn in the homework before i had a chance to look at your replies. However, i did write down the epoxide product along with the answer i had initially. I'll definitely bookmark this and come back to den's reply right after i get it back.


hopefully i'm not annoying some1, who has question, by bringing this post up.