Protons A and B were difficult to determine, however, the coupling point to A corresponding to the
proton near the methoxy groups. It forms a doublet of doublet with G.
B is then the proton hear to the OH group, which gives it a broader peak. It forms a multiplet with
C and G. It also keeps roughly the same shift value it has had throughout the reaction.
It is possible that A and B could be switched however, based on the coupling constant of 5.6 between A and C.
This may merely be a coincidence, or it could point to A and B being switched.
C is the proton near to the N3 which has only one coupling neighbor, B.
D and E correspond to the methoxy group protons. The shift values are so close that it is difficult to determine which is which,
and they should have the same value as they are identical.
F corresponds to proton on the hydroxyl because it has no coupling. It presents as a broad signal.
G is the sp3 protons on the alkane portion.
H is the protons off of the tert-butyl group, whose shift values have remained constant throughout the reaction.