[missUK11]

Hello,

I am finding it difficult to assign the chemical shifts for the protons in this molecule from looking at the literature results below. Firstly, I assigned the protons as shown in the diagram and i assumed that  c and d are diasterotopic, is that correct or are they identical? In the literature results the only protons i understand is 1.42 (s, 9H) which is proton a and 0.92 (d, J=8 Hz, 6H) which is proton f but i'm not sure about protons b,c,d and e.

Can someone please help me to understand the lit results.
Thanks in advance

[Dan]

There are 20H in the NMR, but you have only labelled 19H in your structure - you've missed one of the Hs that is showing up in the NMR. Any idea which it might be?

Look at the splitting patterns you can see. If you have a d, that H is only coupling to one other H - there is only one obvious option as to which one that might be.

[missUK11]

Would the other proton be the N-H proton ? and would that proton be able to couple with proton b to produce a doublet?

thanks

There are 20H in the NMR, but you have only labelled 19H in your structure - you've missed one of the Hs that is showing up in the NMR. Any idea which it might be?

Look at the splitting patterns you can see. If you have a d, that H is only coupling to one other H - there is only one obvious option as to which one that might be.

[Dan]

That would be my guess. How about that quartet?

[missUK11]

Would the quartet be due to proton b coupling with the N-H proton and protons c and d and so the multiplet would be c,d and e ??

That would be my guess. How about that quartet?

[Dan]

That would be my guess as well.

[missUK11]

ok thanks so much

That would be my guess as well.

[Babcock_Hall]

4.9 ppm is more upfield than where I have observed a peak which I tentatively assigned to the carbamate N-H hydrogen atoms of a BOC group (6.9 ppm).  What is the solvent?  Ours was d₆-DMSO.  I checked Hans Reich's NMR tables, and I found a carbamate N-H at 5.16 ppm; perhaps the degree of H-bonding has a strong influence.  I am not sure why all three hydrogen atoms in question would produce the same 4 Hz coupling constant.