# Stereochemistry + isomer check

[Please imagine green bonds as dotted bonds going into the plane]

From compound M, we are told that the 3 membered ring is opened u using sodium azide yielding a mix of isomers N and O.

I drew the following:

and

[Again, please imagine the green bonds as dotted bonds and the blue bonds as wedge bonds]

Given are the following two molecules:

Are my solutions the same as the ones given? If they aren't, where did I go wrong?

Many thanks!

• Your solutions are not the same. You have not considered atttack by azide on the epoxide next to the ether. Jan 4 at 11:48

First of all, for both products, you have not given the O atom in the carbonyl position. In organic chemistry, we assume that there is a C atom if no atom is mentioned specifically. Now for this reaction, the carbonyl group will be there as it is.

Now we can consider the reaction. The epoxide is away from the plane, i.e. below the plane. For the steric reason, it is more feasible for azide to attack from the upper side of the plane. Now again, azide can attack both C centre of the 3-membered epoxide ring. In that case, we'll be having two different products. But in both cases, we will have the azide group on the above of the plane and O atom in the below of the page.

Now if I assume that you have mistakenly skipped the O atom in your both products, then your first molecule matches with the first answer given below. But  the second answer given by you is not correct and doesn't match with the second answer. You can have the green and blue coloured bond in the same place and then you have to alternate the position of OH group and azide group. Then that will match the answer given below and the answer will be correct.

• Thanks @aritaroy24 - you are right - I missed out the carbonyl oxygen by mistake
– rdx
Jan 4 at 12:18
• @aritaroy24 - I also now understand that the azide will attack from the upper side and so the N3 part will always be above the plane. Is there any where I can find out more about this type of attack for olympiad purposes? (I am a high school student in the UK - A level, if that helps)
– rdx
Jan 4 at 12:19
• Google is your friend! Search "nucleophilic opening of epoxides" and you will get hits like this: khanacademy.org/science/organic-chemistry/… Jan 4 at 12:27
• @Waylander is correct. It's just a basic type of reaction. You can find it on google by just typing the words mentioned above. Jan 4 at 12:36