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A sample of an aldehyde has been extracted in almost pure
form (95%) from cucumber.
You are provided with a 1H NMR spectrum (500 MHz; CDCl3)
of the sample. The numbers above the peaks on the proton
spectrum are the relative integrals of the peaks of the major
component.
You are also provided with COSY (showing the couplings
between the peaks of the major component) and HSQC
spectra.
Identify the major component and assign the spectra.
(3)
(2)(2)
(1)
(1)
9
8
7
(2)
(1)
(1)(1)
6
5
4
3
2
1
ppm
(3)
(1)
(1)
(1)
(1)(1)
6
5
(2)(2)(2)
F2
(ppm)
3
4
5
6
7
8
9
9
8
7
F1 (ppm)
4
3
2
HSQC – Cucumber aldehyde
F1
(ppm)
40
60
80
100
120
140
160
180
200
10
9
8
7
6
5
F2 (ppm)
4
3
2
1
You are provided with NMR data for a sample of 5HIndeno[1,2-b]pyridin-5-one at 500 MHz in CDCl3.
Assign the carbon spectrum.
O
3
2
1
N
4
5
12
11
6
10
9
8
7
F2
(ppm)
7.4
7.6
7.8
8.0
COSY
8.2
8.4
8.6
8.8
8.6
8.2
7.8
F1 (ppm)
7.4
F2
(ppm)
7.2
7.4
7.6
7.8
8.0
HSQC
8.2
8.4
8.6
155
145
135
F1 (ppm)
125
115
F2
(ppm)
7.2
7.4
7.6
7.8
8.0
8.2
HMBC
8.4
8.6
8.8
9.0
200
190
180
170
160
150
F1 (ppm)
140
130
120
You are provided with NMR data for a sample of 2-ethyl-1-indanone.
Assign the carbon spectrum
7
O
8
9 1
10
(3)
11
2
4
6
3
(1) (1) (1)
(1)
5
7.75
8
7
7.60
6
7.45
5
ppm
4
(1) (1)
(1) (1) (1)
3
2
ppm
F2
(ppm)
2
3
4
5
COSY
6
7
8
8
7
6
5
4
F1 (ppm)
3
2
1
F2
(ppm)
2
HSQC
3
4
5
6
7
8
130
110
90
70
F1 (ppm)
50
30
10
F2
(ppm)
2
3
4
HMBC
5
6
7
8
180
140
100
F1 (ppm)
80
60
40
20
3,4,-diethyl-5-methyl-2-pyrrolecarboxyllic acid (I) was reacted with ethanol and the product
A was isolated. Mass spectrometry shows the molecular ion to be 18 Daltons less than the
sum of the two reagents. You are provided with 1H NMR, 13C NMR, 1H-1H COSY, HSQC
(one-bond correlation) and the relevant region of the HMBC (two- and/or three-bond
correlation) spectra (400 MHz, CDCl3). Identify the product A and assign the 1H and 13C
NMR spectra.
CH3CH2
CH3
CH3CH2
N
H
(I)
+ CH3CH2OH
CO2H
A
F2
(ppm)
1.5
COSY
2.0
2.5
3.0
3.5
4.0
4.5
4.5
4.0
3.5
3.0
F1 (ppm)
2.5
2.0
1.5
F2
(ppm)
HSQC
2.0
2.5
3.0
3.5
4.0
60
55
50
45
40
35
F1 (ppm)
30
25
20
15
F2
(ppm)
HMBC
2.0
2.5
3.0
3.5
4.0
4.5
160
150
140
F1 (ppm)
130
120
A chemist has prepared a sample which they believe to be
either structure A or structure B.
8
7
6
7
N
5
N
6
1
4
5
8
1
4
3
A
2
3
2
B
By assigning the 1H NOESY spectrum decide which
isomer was made.
The spectra were obtained at 500 MHz in CDCl3 (residual
solvent signal at 7.3 ppm) and the sample also contained
a small amount of CH2Cl2 (signal at 5.3 ppm).
F1
(ppm)
4
5
6
7
8
9
9
8
7
6
F2 (ppm)
5
4
3
F1
(ppm)
7.8
8.0
8.2
8.4
8.6
8.8
9.0
9.2
9.2
8.8
8.4
F2 (ppm)
8.0
7.6
A chemist has prepared a derivative of ramnose. Major and minor fractions
have been isolated by column chromatography and are believed to correspond
to the - and - anomers. Using the NMR data provided, work out which
anomer corresponds to which fraction. As a starting point, in each case the
anomeric hydrogen (H1) has been identified on the spectrum.
NO2
N
5
S
H
1
S
H
5H
3
1
Me
H
O
O
Me
H
H2C
4H
Me
-anomer
2
O
H
O
SiEt3
N
H
H2C
O
S
S
O
O
2
O
H
H3
O
4
NO2
O
SiEt3
Me
-anomer
Major fraction
1
5.4
5.2
5.0
4.8
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
ppm
Minor fraction
1
5.4
5.2
5.0
4.8
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
ppm
Major fraction - COSY
F2
(ppm)
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.2
4.8
4.4
F1 (ppm)
4.0
3.6
3.2
Major fraction - NOESY
F2
(ppm)
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.2
4.8
4.4
F1 (ppm)
4.0
3.6
3.2
Minor fraction - COSY
F2
(ppm)
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.6
5.2
4.8
4.4
F1 (ppm)
4.0
3.6
3.2
Minor fraction - NOESY
F2
(ppm)
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.6
5.2
4.8
4.4
F1 (ppm)
4.0
3.6
3.2
10
1
NH2
NH2
O
S
O
2
S
O
N
9
O
3
8
N
5
4
HN
+
NH2
N
N
HCl
7
+
6
or
O
S
5
O
6
NH
7
4
Cl
N
N
8
9
1
2
3
"A"
NH2
10
"B"
1H
7.6
7.4
NMR, 500 MHz, DMSO-d6
7.2
7.0
6.8
6.6
6.4
6.2
ppm
S
W
11
10
9
8
7
0.95
6
1.00
2.00
5
4
3
2.02
2.06
ppm
0.91
0.56
5.91
13C
NMR, 125 MHz, DMSO-d6
160
140
120
S
100
80
60
40
ppm
F1
(ppm)
3
NOESY
4
5
6
7
8
8
7
6
5
F2 (ppm)
4
3
2
F2
(ppm)
3
HSQC
4
5
6
7
8
140
120
100
90
80
F1 (ppm)
70
60
50
40
30
F2
(ppm)
3
HMBC
4
5
6
7
8
180
160
140
120
100
F1 (ppm)
80
60
40
20