[nehorlavazapalka]

I've got two purine derivatives. One has isopropyl substituent placed at 3, while the other has isopropyl at 9.

How do I get to differentiate between them using NMR? The atoms should be eqivalent and the only thing I can think of is to use simulation software to compare the shifts, but the results are rather ambiguous.

I have 1H, 13C, COSY, HMBC and HMQC available (both compounds), though I do not understand the differences that should be there (other than different shift values).

Thank you very much for answers.

[Archer]

Can you discriminate between the two purine C-H protons by ¹H NMR?

What C-H correlations does HMBC provide?