C8953
NMR structural analysis - seminar
2D NMR spectra, COSY
Jan Novotny
176003@mail.muni.cz
March 20, 2024
1
H-13
C coupled system
58.0 57.8 57.6 57.4 57.2 57.0 56.8 56.6 56.4 56.2 56.0 55.8 55.6 55.4 55.2
ppm
58.0 57.8 57.6 57.4 57.2 57.0 56.8 56.6 56.4 56.2 56.0 55.8 55.6 55.4 55.2
ppm
0
Hz
20406080100120140
O
N
HA
HB
Ph
Problem R-12M. You are asked to interpret the coupled 13
C NMR spectrum of an oxazoline.
(a) Which carbon are we looking at?
(b) Analyze the spectrum, report all coupling constants in the standard format (n
JX-Y = 00.0 Hz).
(c) The spectrum below is of the same compound with one H replaced by D. Where is the deuterium? Place it on
the structure, and explain briefly.
(d) What is the proton NMR frequency of the spectrometer they were using?
HC
HC
2
3
5
6
O
N
Ph
2
3
5
6
15
1
H NMR spectrum of naringenine in d6-acetone
1
H NMR spectrum of naringenine in d6-acetone
1
2
3
5a,b
4
6
8
9
7
9
1
7
2
3
6
8
4
5a,b
2D NMR
Second dimension f1
▶ preparation period
=⇒ coherence
▶ evolution period
t1
FT
−→ f1
▶ increments
▶ evolution of
coherence
▶ mixing period
▶ transfer of
encoded
magnetization
▶ measurable
signal
▶ detection of signal
t2
FT
−→ f2
acq
t1
prep
evolution
mixing
detection
t2
5t1
4t1
3t1
2t1
t1
2D NMR
2D spektrum
▶ FT in t1 - modulated 1D spectra
▶ FT in t2 - 2D spectrum
COSY
▶ easiest 2D
experiment
▶ correlates H nuclei
based on 2/3J
coupling
▶ through 2, 3, (4)
bonds
▶ antiphase
off-diagonal
crosspeak between
coupled atoms
▶ DQF-COSY modification
of basic
sequence, diagonal
crosspeaks in
absorption phase
acq
t1 t2
))
90 9090
P E M D
f1
f2
f1
f2
Hints for beginners
▶ Determination of individual spin systems - sharing
off-diagonal crosspeaks
▶ Isolated protons - only diagonal crosspeak
▶ Already known rules: symmetry, diastereotopicity, most
shielded/deshielded atoms etc.
COSY : β-cyclodextrine
5.0
5.0
4.5
4.5
4.0
4.0
3.5
3.5
δ2 - 1
H (ppm)
5.0 5.0
4.5 4.5
4.0 4.0
3.5 3.5
δ1-1
H(ppm)
COSY : β-cyclodextrine
5.0
5.0
4.5
4.5
4.0
4.0
3.5
3.5
δ2 - 1
H (ppm)
5.0 5.0
4.5 4.5
4.0 4.0
3.5 3.5
δ1-1
H(ppm)
H1'-H1'
H1'-H2' H2'-H2'H3'-H2'
H3'-H4'
H3'-H3'
H4'-H4'
H5'-H4'
H6'-H5'
Phase sensitive COSY
▶ direct vs. indirect dimension
▶ active coupling - antiphase crosspeak, passive coupling -
in-phase
Phase sensitive COSY
▶ direct vs. indirect dimension
▶ active coupling - antiphase crosspeak, passive coupling -
in-phase
Phase sensitive COSY
▶ direct vs. indirect dimension
▶ active coupling - antiphase crosspeak, passive coupling -
in-phase
Phase sensitive COSY
▶ direct vs. indirect dimension
▶ active coupling - antiphase crosspeak, passive coupling -
in-phase
Phase sensitive COSY
▶ direct vs. indirect dimension
▶ active coupling - antiphase crosspeak, passive coupling -
in-phase
Phase sensitive COSY
▶ direct vs. indirect dimension
▶ active coupling - antiphase crosspeak, passive coupling -
in-phase
Phase sensitive COSY
▶ direct vs. indirect dimension
▶ active coupling - antiphase crosspeak, passive coupling -
in-phase
Phase sensitive COSY
▶ direct vs. indirect dimension
▶ active coupling - antiphase crosspeak, passive coupling -
in-phase
1D 1
H of Atropine in DMSO
COSY : Atropine
8
8
6
6
4
4
2
2
8 8
6 6
4 4
2 2
δ1-1H(ppm)
COSY : Atropine
5
5
4
4
3
3
2
2
1
1
1
5 5
4 4
3 3
2 2
δ1-1
H(ppm)
COSY : Atropine
5
5
4
4
3
3
2
2
1
1
1
5 5
4 4
3 3
2 2
δ1-1
H(ppm)
8OH-H8''
8OH-H8' H8''-H8'
H7'-H8'
H8''-H7'
H10-H11''/H16''
H10-H11'/H16'
H12-H11''
H12-H11'
H15-H16'
H15-H16''
H15-H14''
H12-H13
H13-H14''
H13-H14'
H14''-H14'
H17-H17
Chinin - 1D 1
H
COSY - Chinin
10
10
8
8
6
6
4
4
2
2
δ2 - 1H (ppm)
8 8
6 6
4 4
2 2
δ1-1H(ppm)
5
10
6
9
7
8
3
2
4
N
1
O
CH3
22
11
12
OH
17
16
N
13
15
14
18
19
20
21
COSY - Chinin10 8 6 4 2
8 8
6 6
4 4
2 2
δ1-1H(ppm)
5
10
6
9
7
8
3
2
4
N
1
O
CH3
22
11
12
OH
17
16
N
13
15
14
18
19
20
21
COSY - Chinin
10
10
8
8
6
6
4
4
2
2
δ2 - 1H (ppm)
8 8
6 6
4 4
2 2
δ1-1H(ppm)
5
10
6
9
7
8
3
2
4
N
1
O
CH3
22
11
12
OH
17
16
N
13
15
14
18
19
20
21
21
15,17
14,18
COSY - Chinin
10
10
8
8
6
6
4
4
2
2
δ2 - 1H (ppm)
8 8
6 6
4 4
2 2
δ1-1H(ppm)
5
10
6
9
7
8
3
2
4
N
1
O
CH3
22
11
12
OH
17
16
N
13
15
14
18
19
20
21
21
15,17
14,18
H20-H21'/H21''
H20-H19
H19-H18'/18''
H14'/''-H15'/''
COSY - Chinin
10
10
8
8
6
6
4
4
2
2
δ2 - 1H (ppm)
8 8
6 6
4 4
2 2
δ1-1H(ppm)
5
10
6
9
7
8
3
2
4
N
1
O
CH3
22
11
12
OH
17
16
N
13
15
14
18
19
20
21
15,17
H12-H17'/''
H11-H12
H3-H11
H2-H3
COSY - Chinin
10
10
8
8
6
6
4
4
2
2
δ2 - 1H (ppm)
8 8
6 6
4 4
2 2
δ1-1H(ppm)
5
10
6
9
7
8
3
2
4
N
1
O
CH3
22
11
12
OH
17
16
N
13
15
14
18
19
20
21
H8-H6
H9-H8
NOESY-600ms
H6-H11
H8-H22 H6-H22
H3-H17
H2
H3
H9
H8
H6
H11
H11
H12
H17''
H17'
H21
H20
H19
H18'
H18''
H14''
H15''
H15'
H22
H16-H17'
H19-H16
Next topic
1H-1H through space correlations (NOESY, ROESY)