1. Tutorial on 2D-NMR: Using COSY & HSQC to Assist in Assigning 1H & 13C NMR Spectra

2. 1H NMR Chemical shift (δ) depends on molecular structure and solvent
1H nuclei sensitive to hybridization of atom to which H is attached and electronic effects
EDG’s shield nuclei  shift upfield  lower δ
EWG’s deshield nuclei  shift downfield  higher δ
Downfield
Deshielded
Upfield
Shielded
10 ppm
0 ppm

3. 1H NMR
Spin-spin coupling effects: interaction between nuclei through bonds
Causes splitting in observed peak (s, d, dd, t, m…)
Coupling constants: magnitude of splitting (Hz)
Hz (not ppm) since effect is independent of applied mag. fld.
Caused by mag. fld. of another nuclei

4. 2-D NMR
Determine structure (especially for molecules too complicated for 1-D NMR)
Involves series of 1-D NMR experiments
Doesn’t need to use the complicated coupling constants

5. Correlation Spectroscopy (COSY)
Homonuclear: plots 1H NMR on both x and y-axis
Diagonal divides the spectrum into 2 equal halves
Cross-signals: symmetrical to diagonal; contain the relevant info
FAB-FOUR
1H NMR (~5 min)
COSY (~30 min)
13C NMR (depends…)
HSQC (~30 min)

11. H2 H4 H3 H3 3 H4 4 H2 2

12. H6 H8 H2 H4 H7 H3 H3 3 H7 7 H4 4 H8 8 H2 2 H6 6

13. H1 H6 H8 H2 H4 H7 H3 H3 3 H7 7 H4 4 H8 8 H2 2 H6 6 H1 1

14. H5 H1 H6 H8 H2 H4 H7 H3 H3 3 H7 7 H4 4 H8 8 H2 2 H6 6 H1 1 H5 5

15. H11 H9 H5 H1
H10 H6 H8 H2 H4 H7 H3 H3 3 H7 7 H4 4
H10 10 H8 8 H2 2 H6 H9 6 9
H11 11 H1 1 H5 5

16. H11 H9 H5 H1
H10 H6 H8 H2 H4 H7 H3 H3 3 H7 7 H4 4
H10 10 H8 8 H2 2 H6 H9 6 9
H11 11 H1 1 H5 5

17. LONG-RANGE COUPLING H11 H9 H10 H5 H1 H8 H6 H2 H4 H7 H3 H3 3 H7 7 H4 4

18. Heteronuclear Single Quantum Coherence (HSQC)
Plots 1H NMR on x-axis and 13C NMR on y-axis
Utilizes 1 bond coupling between H and C
Eliminating all the H containing C’s eliminates many C’s assignments
Leaves only on-H containing C’s to assign

19. HSQC Spectrum

20. H11 H9 H5 H1
H10 H6 H2 H8 H4 H7 H3 5 1 10 3 7 11 6 2 8 4 9

21. H11 H9 H5 H1
H10 H6 H2 H8 H4 H7 H3 5 1 10 3 7 11 6 2 8 4 9

22. # of total peaks: 5 1 3 1 4 2
# of non-H C peaks: 2 1 1 1
??????????
C12, C13, C14, C15, C17
??????????
C14, C15, C17 C6 C7 C1 C8 C2 C9 C3
C11 C5 C4
C10
C13
C12

23. Thank You Any Questions?