1H and 13C NMR spectral assignment of N,N′-disubstituted thiourea and urea derivatives active against nitric oxide synthase

Article abstract of DOI:10.1002/mrc.4455

The ¹H and ¹³C NMR resonances of seventeen N-alkyl and aryl-N′-[3-hydroxy-3-(2-nitro-5-substitutedphenyl)propyl]-thioureas and ureas (1–17), and seventeen N-alkyl or aryl-N′-[3-(2-amino-5-substitutedphenyl)-3-hydroxypropyl]-thioureas and ureas (18–34), designed as NOS inhibitors, were assigned completely using the concerted application of one- and two-dimensional experiments (DEPT, HSQC and HMBC). NOESY studies confirm the preferred conformation of these compounds. Copyright

Full text of DOI:10.1002/mrc.4455

Research article
Received: 11 January 2016
Revised: 20 April 2016
Accepted: 25 April 2016
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/mrc.4455
1
13
H and C NMR spectral assignment of N,N′-
disubstituted thiourea and urea derivatives
active against nitric oxide synthase
Mariem Chayah, M. Encarnación Camacho,* M. Dora Carrión*
and Miguel A. Gallo
1
13
ABSTRACT The H and C NMR resonances of seventeen N-alkyl and aryl-N′-[3-hydroxy-3-(2-nitro-5-substitutedphenyl)propyl]-
thioureas and ureas (1–17), and seventeen N-alkyl or aryl-N′-[3-(2-amino-5-substitutedphenyl)-3-hydroxypropyl]-thioureas and
ureas (18–34), designed as NOS inhibitors, were assigned completely using the concerted application of one- and two-
dimensional experiments (DEPT, HSQC and HMBC). NOESY studies confirm the preferred conformation of these compounds.
Copyright © 2016 John Wiley & Sons, Ltd.
1
13
1
13
1
15
Keywords: H and C 1D NMR; H/ C 2D NMR (HSQC; HMBC); H/ N 2D NMR (HSQC; HMBC); NOESY; N,N′-disubstituted thioureas and
ureas; hydroxypropylthioureas; hydroxypropylureas
The present study reports the unambiguous assignment of each
Introduction
1
13
signal in the H and C NMR spectra in compounds 18–34, using
one-dimensional and two-dimensional resonance techniques. The
spectra of nitro derivatives 1–17, the precursors in their synthetic
pathway, are also included.
Nitric oxide (NO) is an inorganic free radical and an important
biomessenger that regulates several physiological functions in the
[
1]
nervous, immune and cardiovascular systems. NO is synthesized
from the enzyme catalysis of L-arginine to L-citrulline in several cell
types by a family of NO synthase (NOS) isoenzymes with consump-
tion of molecular oxygen. In mammalians, three isoforms of NOS
have been identified: neuronal (nNOS), endothelial (eNOS) and
inducible NOS (iNOS). nNOS and eNOS are constitutive and regu-
lated by intracellular Ca/Calmoduline. They continually produce low
levels of NO used for nerve function and blood regulation, respec-
tively. While, iNOS produces large toxic bursts of NO to fight path-
Experimental
[2]
NMR spectra
Nuclear magnetic resonance (NMR) spectra were recorded on a
1
13
3
00-MHz H and 75-MHz C NMR Agilent Varian Innova Unity,
1
13
a 400-MHz H and 100 MHz C NMR Agilent Varian Direct Drive,
a 500-MHz H and 125-MHz C NMR Agilent Varian Innova
[
3,4]
ogens, and is not Ca dependent.
1
13
To exert appropriate functions, NO synthesis by the three
isozymes is under tight regulation. Thus, overproduction of NO by
nNOS has been associated with neurodegenerative disorders such
as Alzheimer, Parkinson or Huntington diseases,
ible isoform seems to be responsible for the massive NO production
in pathologies such as arthritis, colitis, tissue damage, cancer or sev-
1
13
Unity and a 600-MHz H and 150-MHz C NMR Agilent Varian
Direct Drive spectrometers at 298K. The following parameters
were used in DEPT experiments: pulse width (135°), 9.0ms;
recycle time, 1 s; ½ J (CH)= 4 ms; 65 536 data points acquired
and transformed from 1024 scans; spectral width, 15 KHz; and
line broadening, 1.3 Hz. Chemical shifts (δ) are quoted in parts
per million (ppm) and are referenced to the residual solvent
[5–7]
and the induc-
[8–10]
eral inflammatory states.
been associated with hypertension and atherosclerosis.
The NO underproduction by eNOS has
[11,12]
Accord-
1
13
peak: CDCl3, δ = 7.26 ppm ( H), δ = 77.4 ppm ( C); CD OD,
3
ingly, inhibition of nNOS or iNOS, but not of eNOS, could provide an
effective therapeutic approach. Because of this, the development of
NOS selective inhibitors is an important field of research.
In a recent paper, the synthesis and biological evaluation of a
novel family of N,N′-disubstituted thiourea and urea derivatives
1
13
δ = 3.31 ppm ( H), δ = 49.00ppm ( C). Spin multiplicities are
given as s (singlet), bs (broad singlet), d (doublet), dd (doublet
doublet), t (triplet), q (quadruplet) and m (multiplet). Coupling
constant (J) is given in Hz.
1
8–34, which were designed and evaluated as NOS inhibitor
[
13]
agents, have been described.
Although the structures of these derivatives have been deter-
mined by means of standard spectroscopic ( H, C NMR) and
spectrometric (MS) techniques, a detailed NMR study has been
performed in some of them, in order to unequivocally corroborate
their structures.
*
Correspondence to: M. Encarnación Camacho and M. Dora Carrión,
Departamento de Química Farmacéutica y Orgánica, Facultad de Farmacia,
Universidad de Granada, c/ Campus de Cartuja, s/n. 18071 Granada, Spain. E-
mail: ecamacho@ugr.es; dcarrion@ugr.es
1
13
Departamento de Química Farmacéutica y Orgánica, Facultad de Farmacia,
Universidad de Granada, 18071, Granada, Spain
Magn. Reson. Chem. (2016)
Copyright © 2016 John Wiley & Sons, Ltd.

M. CHAYAH ET AL.
The HMBC spectra were measured with a pulse sequence
gc2hmbc (standard sequence, Agilent Vnmrj_3.2A software)
optimized for 8 Hz (inter-pulse delay for the evolution of long-range
couplings: 62.5 ms). The HSQC spectra were measured with a pulse
sequence gc2hsqcse (Standard sequence, Agilent Vnmrj_3.2A
software).
H/ N 2D NMR (HSQC, HMBC) spectra were recorded on a 600-
MHz Agilent Varian Direct Drive spectrometer using a High-Field
Triple Resonance Probe (HCN). Ammonia was used as an external
carbons, (iii) HMBC sequences to assign the signals of quaternary
carbons via two-bond and three-bond interactions, (iv) HMBC and
1
15
HSQC H/ N experiments to establish the shifts of amino group
and thiourea and urea moieties and (v) NOESY experiments to
determinate the preferred conformation in solution.
1
Tables 2 and 3 show the H NMR signals of each proton for
1
15
compounds 1–34, whereas Tables 4 and 5 show the corresponding
1
3
C NMR chemical shifts for the same molecules. The NMR spectra
of the intermediate compounds were carried out in CDCl solution,
except for compound 2, which was registered in CD OD. The NMR
spectra of the final compounds were carried out in CD OD solution,
except for compounds 19, 20, 22 and 24, which were accom-
plished in CDCl . For this reason, some significant variations are
observed in the chemical shifts depending of the solvent.
3
standard set at 0.0 ppm and (CD
sample.
3
)
2
SO was used as a solvent in each
3
3
Nuclear Overhauser spectra were recorded on a Agilent Varian
Direct Drive spectrometer, operating at 600MHz, with a spectral
widths of 4.96 KHz in both F2 and F1 domains; 744 × 200 data
points were acquired with 16 scans per increment and relaxation
delays of 1.0s. The mixing time in NOESY experiments was 0.5 s.
Data processing was performed on a 1K × 1K data matrix.
3
1
13
H NMR signals (H-1′ and H-2′) and C NMR signals (C-2, C-1′,
C-2′, C-4″ and C-6″) are similar in both, intermediate and final
compounds: N-alkyl or aryl-N′-[3-hydroxy-3-(2-nitro-5-
substitutedphenyl)propyl]-thioureas and ureas 1–17, and N-alkyl or
aryl-N′-[3-(2-amino-5-substitutedphenyl)-3-hydroxypropyl]-thioureas
and ureas 18–34; however, H-3′, H-3″-H-6″, C-3′, C-1″-C-3″ and C-5″ are
influenced by the activating and deactivating effects of the amine or
nitro groups, respectively. C-2 of the main chain is influenced by the
sulfur or oxygen atoms present in the thiourea or urea rest, but not by
the nitro or amino group. Finally, H-1 and H-3 signals, linked to
nitrogen atoms, do not follow the same pattern and sometimes are
not visible.
Results and Discussion
Scheme 1 represents the previously reported synthetic pathway
followed in the preparation of final compounds 18–34,
Table 1 shows the structural data of all the synthesized intermediate
and final compounds.
[13]
and
Structural elucidation of these compounds has been made by
1
13
13
routine H and C NMR techniques. Nevertheless, a definitive
assignment of all signals needs the use of several NMR techniques
as follows: (i) DEPT experiments to determine the number of
protons attached to each carbon atom, (ii) HSQC spectra to deter-
HSQC and HMBC C experiments were performed on all
compounds of each series. Here we comment some of them.
Table 6 shows the HSQC correlations for compounds 3, 5, 8, 9,
12, 15, 19, 22, 24, 26, 30 and 32, whereas Fig. 1 shows the more
important connectivities found in the HMBC spectra of compounds
1
3
mine the C resonances of the tertiary, secondary and primary
5, 9, 12, 18, 29 and 32.
HSQC experiments performed on compounds 3, 5, 8, 9, 12 and
5 allowed the assignment of the secondary carbon atoms
1
chemical shifts C-1′ and C-2′, and the assignment of the tertiary
carbon atoms chemical shifts C-3′, C-3″, C-4″, C-5″ and C-6″ in the
nitro derivatives 1–17. These atoms show signals in ranges of
3
1
6.86–44.33 (C-1′), 38.48–39.95 (C-2′), 65.63–66.69 (C-3′),
23.87–128.09 (C-3″), 113.38–134.13 (C-4″), 127.65–164.61 (C-5″)
and 111.91–128.53 (C-6″).
Similar HSQC experiments performed on compounds 19, 22, 24,
13
2
6, 30 and 32 indicate that the C NMR signals for the analogue
secondary and tertiary carbon atoms in the final amino-phenyl
derivatives 18–34 are in the following ranges: 36.89–42.21 (C-1′),
Scheme 1. Synthesis of N,N′-disubstituted thiourea and urea derivatives
1
8–34. a) CH
c) XCNR , CH
0 °C, 60 bar.
3
CN, BuLi, THF, À78 °C, then RT; b) BH
3
-THF, 0 °C, then 4 h RT;
34.69–39.40 (C-2′), 69.08–74.02 (C-3′), 117.06–121.11 (C-3″),
2
2 2
Cl , 20 min (MW); d) 10% Pd/C, MeOH (flow hydrogenation),
6
113.13–131.30 (C-4″), 117.67–155.80 (C-5″) and 112.25–130.27 (C-6″).
The quaternary carbons signals were confirmed by HMBC spectra
on the intermediate (3, 5, 9 and 12) and final (18, 29 and 32)
compounds (Fig. 1). In compound 3, correlations between H-6″ (δ
Table 1. Structural data of the intermediate (1–17) and final (18–34)
compounds
13
7.90) and H-5″ (δ 7.41), and the C at 147.10 ppm, and between
13
H-3″ (δ 7.94) and H-4″ (δ 7.65), and the C signal at 140.18 ppm
allows the unequivocal assignment of C-1″ and C-2″, respectively.
The correlation between H-1′b (δ 3.50) and the peak at
181.91 ppm allows the assignment of this shift to C-2. In addition,
HMBC spectrum of compound 5 indicates a correlation between
Compound
R
1
R
2
X
Compound
R
1
R
2
X
1, 18
2, 19
3, 20
4, 21
5, 22
6, 23
7, 24
8, 25
H
H
H
Me
Et
S
S
S
S
S
S
S
S
9, 26
10, 27
11, 28
12, 29
13, 30
14, 31
15, 32
16, 33
H
Et
O
O
O
O
O
O
O
O
O
H
H
Pr
Ph
Et
Pr
13
OMe
OMe
Cl
Me
Pr
OMe
OMe
OMe
Cl
OCH (δ 3.91) and the C at δ 164.61 ppm, that can be assigned
3
Pr
Ph
Et
to C-5″. In a similar way, in compound 9, the correlation of H-5″
13
Me
Et
(δ 7.37) and H-3′ (δ 5.30) with C at 147.06 indicates that this
13
Cl
shift corresponds to C-1″. Also, when a C at 140.46 ppm correlates
with H-3″ (δ 7.90), H-4″ (δ 7.63) and H-3′ (δ 5.30), it can be identified
as C-2″. Regarding C-2, it corresponds to a signal appearing at
Cl
Pr
Cl
Pr
Ph
17, 34
Cl
159.61 ppm because of the correlation with H-1′b (δ 3.50) and
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Copyright © 2016 John Wiley & Sons, Ltd.
Magn. Reson. Chem. (2016)

NMR assignments of new N,N′-disubstituted thiourea and urea derivatives
Magn. Reson. Chem. (2016)
Copyright © 2016 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/mrc

M. CHAYAH ET AL.
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Copyright © 2016 John Wiley & Sons, Ltd.
Magn. Reson. Chem. (2016)

NMR assignments of new N,N′-disubstituted thiourea and urea derivatives
13
Table 4. C NMR chemical shifts of compounds 1–17
Compound
C-2
C-1′
C-2′
C-3′
C-1″
C-2″
C-3″
C-4″
C-5″
C-6″
OCH
3
1
182.69
185.83
181.91
181.77
182.16
182.41
181.45
181.57
159.61
159.87
157.62
159.78
159.77
157.52
159.65
159.75
157.65
42.09
44.33
42.16
42.04
42.41
41.79
41.75
41.76
36.96
37.11
37.20
37.17
37.29
37.04
36.86
36.86
36.89
38.92
38.48
38.83
38.62
39.08
38.84
38.80
38.89
39.70
39.95
39.07
39.73
39.28
39.07
39.76
39.81
39.32
66.09
66.13
66.26
66.22
66.60
66.67
66.69
66.65
65.91
66.05
66.39
66.35
66.39
66.53
65.66
65.63
65.90
146.98
147.37
147.10
144.04
144.37
142.57
142.53
142.58
147.06
147.28
147.07
144.63
144.46
144.30
142.88
142.85
142.67
140.26
140.47
140.18
139.51
139.96
144.83
144.90
144.88
140.46
140.61
140.20
139.86
139.70
139.62
145.07
145.07
144.98
124.61
123.87
124.60
127.70
128.09
126.15
126.09
126.10
124.18
124.32
124.30
127.57
127.39
127.52
125.89
125.89
126.00
134.13
133.30
134.07
113.55
113.93
128.07
128.02
128.02
133.70
133.82
133.75
113.59
113.38
113.42
127.80
127.79
127.91
128.09
127.72
128.12
164.22
164.61
140.79
140.71
140.72
127.65
127.78
127.82
164.23
164.05
164.10
140.53
140.54
140.61
128.26
128.00
128.24
111.97
112.37
128.44
128.44
128.46
128.18
128.35
128.42
112.02
111.95
111.91
128.53
128.52
128.44
—
—
a
2
3
4
5
6
7
8
9
—
55.98
56.36
—
—
—
—
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
—
—
56.06
55.89
55.89
—
—
—
a
3
Solvent used CD OD.
1
3
δ (ppm) relative to CDCl
CH CH CH : 45.88, 22.46, 11.81; 6, CH
2.67, 23.43, 11.42; 11, Ph: 137.84, 129.36, 121.81, 121.04; 12, CH
24.12, 121.52; 15, CH CH : 35.65, 15.25; 16, CH CH CH : 42.60, 23.25, 11.27; 17, Ph: 137.76, 129.43, 124.64, 122.09.
3
. C signals for the R
2
substituent: 1, CH
CH : 38.68, 13.99; 8, CH
CH : 35.77, 15.43; 13, CH
3
: 29.93; 2, CH
2
CH
3
: 36.70, 11.87; 3, CH
CH : 45.67, 22.10, 11.41; 9, CH
CH CH : 42.61, 23.15, 11.23; 14, Ph: 138.15, 129.28,
2
CH
2
CH
3
: 45.65, 22.20, 11.55; 4, CH
3
: 30.31; 5,
2
2
3
3
: 30.29; 7, CH
2
3
2
CH
2
3
2 3 2 2 3
CH : 35.56, 15.27; 10, CH CH CH :
4
1
2
3
2
2
3
2
3
2
2
3
13
Table 5. C NMR chemical shifts of compounds 18–34
Compound
C-2
C-1′
C-2′
C-3′
C-1″
C-2″
C-3″
C-4″
C-5″
C-6″
OCH
3
a
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
8
9
0
181.71
181.25
181.61
182.41
181.63
181.67
182.70
181.17
159.98
161.53
160.84
161.40
160.09
157.13
159.97
159.99
157.14
42.10
42.09
42.13
38.38
42.21
41.16
40.64
41.24
37.00
38.43
40.65
38.39
36.97
36.92
36.91
36.92
36.89
37.64
34.69
34.82
36.51
35.18
34.81
34.73
34.85
35.90
37.35
39.40
37.67
36.26
36.01
35.94
35.93
35.65
72.55
71.12
71.35
72.27
70.78
69.08
69.25
69.15
70.07
71.52
74.02
70.94
69.55
69.77
69.22
69.32
69.44
130.83
127.08
127.18
131.26
129.60
129.94
128.98
129.93
128.19
129.61
131.92
131.79
130.33
130.37
130.15
130.23
130.01
147.42
144.70
144.91
134.34
137.56
143.62
142.94
143.63
144.89
146.32
148.58
139.07
137.70
137.64
143.45
143.54
143.71
119.16
116.96
117.06
121.11
118.71
117.36
118.03
117.35
116.47
117.90
120.22
119.39
117.95
118.02
117.48
117.58
117.38
130.29
127.12
127.22
115.91
113.95
126.02
126.75
126.02
127.56
128.99
131.30
114.52
113.13
113.14
126.11
126.11
126.10
120.45
118.54
118.62
155.80
153.16
121.99
123.14
121.98
117.67
119.09
121.42
154.32
152.88
152.92
122.11
122.15
121.94
129.13
128.67
128.83
114.99
113.07
127.15
128.17
127.14
126.54
127.97
130.27
113.66
112.27
112.25
127.10
127.15
127.13
—
—
—
a
1
2
57.35
55.92
—
a
3
4
—
a
5
—
a
6
—
a
7
—
a
8
—
a
9
56.09
54.70
54.67
—
a
0
a
1
a
2
a
3
—
a
4
—
a
3
Solvent used CD OD.
1
3
δ (ppm) relative to CDCl
2, CH CH CH : 45.94, 22.33, 11.56; 23, CH
CH CH CH : 42.88, 24.47, 11.62; 28, Ph: 143.26, 132.04, 125.67, 122.55; 29, CH
39.55, 128.35, 121.99, 118.87; 32, CH
3
. C signals for the R
2
substituent: 18, CH
3
: 32.02; 19, CH
: 46.39, 14.10; 25, CH
CH : 35.85, 15.76; 30, CH
2
CH
3
: 38.87, 14.18; 20, CH
CH CH : 45.56, 21.98, 10.20; 26, CH
CH CH : 41.47, 23.04, 10.19; 31, Ph:
2
CH
2
CH
3
: 46.03, 22.31, 11.55; 21, CH
3
: 31.05;
2
2
2
3
3
: 29.30; 24, CH CH
2
3
2
2
3
2 3
CH : 34.41, 14.34; 27,
2
2
3
2
3
2
2
3
1
2
CH
3
: 34.43, 14.33; 33,CH
2
CH
2
3
CH : 42.83, 22.58, 10.46; 34, Ph: 139.52, 128.36, 122.02, 118.90.
CH CH (δ 3.19). Moreover, in the spectrum of compound 12, H-3″
whereas H-6″ signal (δ 7.06) and H-4″ signal (δ 6.95) are correlated
with the C signal at δ 147.42ppm; thereby, this signal corresponds
2
3
13
13
(δ 8.03), H-6″ (δ 7.41) and OMe (δ 3.90) have a correlation with
C
at 164.23; thus, it can be assigned to C-5″.
to C-2″. Besides, in compound 29, correlations of H-3″ signal (δ 6.71),
13
HMBC experiment performed on compound 18 indicates that
the signals at δ 6.66 (H-3″), 6.61 (H-5″) and 4.72 (H-3′) are correlated
H-3′ signal (δ 4.76) and H-2′a (δ 1.94) with C signal at 131.79ppm
indicate that this signal can be designated as C-1″. Similarly, the
1
3
13
with the C signal at 130.83ppm, which can be assigned to C-1″,
correlations of H-6″ (δ 6.79) and H-3′ (δ 4.76) signals with C signal
Magn. Reson. Chem. (2016)
Copyright © 2016 John Wiley & Sons, Ltd.
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M. CHAYAH ET AL.
Table 6. HSQC correlations found for compounds 3, 5, 8, 9, 12, 15, 19, 22, 24, 26, 30 and 32
1 13
H/ C
Compound
3
5
8
9
12
15
19
22
3.58
24
26
30
32
H-1′
C-1′
H-2′
C-2′
H-3′
C-3′
H-3″
3.50, 2.05
42.16
4.38, 3.49
42.41
3.55
3.78, 3.50
36.96
3.83, 3.20
37.17
3.82, 3.20
36.86
3.92, 3.41
42.09
4.45, 4.30
40.64
3.24
3.30
3.29
41.76
2.04, 1.71
38.89
5.41
42.21
2.13, 1.94
35.18
4.77
37.00 36.97 36.91
1.95 1.99 1.91
35.90 36.26 35.94
4.75 4.81 4.71
70.07 69.55 69.22
6.71 6.76 6.67
2.05, 1.80
38.83
2.03, 7.73
39.08
1.97, 1.65
39.70
1.98, 1.58
39.73
1.96, 1.58
39.76
2.18, 1.95
34.69
2.10, 1.92
34.73
5.35
5.48
5.30
5.45
5.33
4.78
4.76
66.26
66.60
66.65
7.95
65.91
66.35
65.66
71.12
70.78
6.62
69.25
7.94
8.07
7.90
8.03
7.90
6.64
6.56
C-3″ 124.60
124.32
124.18
7.63
124.60
128.09
6.84
126.10
7.38
127.57
6.82
125.89
7.34
116.96
7.06
118.71
6.66
118.03
7.00
116.71 117.95 117.48
7.01 6.71 6.97
H-4″
7.65
C-4″ 134.07
H-5″ 7.41
C-5″ 128.12
H-6″ 7.90
C-6″ 128.24
113.93
128.02
133.70
7.37
113.59
127.80
127.12
6.71
113.95
126.75
127.56 113.13 126.11
6.67
127.65
7.90
118.54
7.06
117.67
7.40
7.95
7.41
7.93
6.69
7.05
7.09
6.83
7.10
112.37
128.46
128.18
112.02
128.53
128.67
113.07
128.17
126.54 112.27 127.10
1
13
Figure 1. Important connectivities found in the HMBC H/ C spectra of compounds a) 1–17 and b) 18–34.
at 139.07 ppm demonstrate that this signal corresponds to C-2″.
Moreover, the correlations between H-6″ (δ 7.10) and H-3″ (δ 6.67),
and a signal at 122.11 ppm indicates that this signal corresponds
to C-5″. Finally, the peak at 159.97 ppm which correlated with H-1′
b (δ 3.29) and CH CH (δ 3.20) is identified as C-2.
HSQC and HMBC N experiments were carried out on selected
compounds (25, 26 and 30) in order to determine the N and
protons’ chemical shifts of the amino, thiourea and urea groups
(Table 7, Fig. 2). These experiments were performed on a 600-
13
The correlation between OMe (δ 3.73) and C signal at 56.09 ppm
allows the assignment of this peak to C-5″. Finally, H-1′a (δ 3.30),
H-1′b (δ 3.23) and CH CH (δ 3.15) are correlated with the peak at
2
3
2
3
1
5
161.40 ppm, thus is identified as C-2. Last, HMBC experiment on
the urea 32 demonstrates that H-3″ (δ 6.67), H-3′ (δ 4.71) and H-2′
13
a (δ 1.91) are correlated with the C at 130.15 which corresponds
to C-1″, whereas H-6″ (δ 7.10), H-4″ (δ 6.97) and H-3′ (δ 4.71) are cor-
related with the peak at 143.45 ppm that can be assigned to C-2″.
MHz spectrometer using (CD
3
)
2
SO as solvent, thereby some signals’
1
15
Table 7. HSQC H/ N experiments spectroscopic data of compounds 25, 26 and 30
25
26
30
H-1
H-3
-NH
2
H-1
H-3
-NH
2
H-1
H-3
-NH
2
N-1
N-3
7.34
12.05
—
—
—
5.80
81.59
—
—
—
5.90
81.84
—
—
—
1
7.34
12.84
—
—
5.78
85.46
—
—
5.77
82.06
—
—
1
―NH
2
—
5.07
8.65
—
4.90
57.73
—
4.48
51.96
5
1
15
Figure 2. Important connectivities found in the HMBC H/ N spectra of compounds 25, 26 and 30.
wileyonlinelibrary.com/journal/mrc
Copyright © 2016 John Wiley & Sons, Ltd.
Magn. Reson. Chem. (2016)

NMR assignments of new N,N′-disubstituted thiourea and urea derivatives
1
13
shift has slightly changed (respect to the previous H and
C
experiments).
Regarding the thiourea 25, the HSQC indicates a multiplet at
7.34 ppm (corresponding to H-1 and H-3) correlated with the signal
of the N-1 (112.05ppm) and N-3 (112.84 ppm). Moreover, the corre-
lation between the nitrogen of the amino group (58.65 ppm) and
the broad singlet at 5.07 ppm enables the assignments of the
Figure 3. Selected NOESY correlations for compound 25.
2
protons of the amino group (―NH ). These designations were con-
firmed by HMBC experiment. The peak at 112.05 ppm is correlated
with H-2′ (m, 1.83 ppm), which allows the unequivocal assignment
3
3
9.9 ppm, and in the second compounds the range is between
8.5 and 39.9ppm; the C-3′ atom in the hydroxylpropyl derivatives
15
of N-1. In addition, there is a correlation between the N at
12.84 and the multiplet at 1.45 ppm corresponding to
CH ―CH ―CH , indicating that this shift belongs to N-3. Finally
a correlation between the signal at 58.65 ppm and the multiplet at
.57 corresponding to H-3″, allows to determine the shift of the
amino group (―NH ).
1
shows signals in range of 65.6–66.7 ppm, and in the oxopropyl
molecules fluctuates between 200.6 and 202.8 ppm, because of
the change of a hydroxyl group by a carbonyl one; finally, the
C-1″ in this new compounds appears in the range of
―
2
2
3
6
2
1
1
42.5–147.4 ppm (in the nitro-derivatives) and between 127.1 and
31.9ppm (in the amine-derivatives), and in the structures with
According to the HSQC spectra of 26, the N-1 (δ 81.59) is corre-
lated with a multiplet at 5.80ppm, and N-3 (δ 85.46) with a multiplet
at 5.78 ppm. These correlations enable the assignment of H-1
an oxopropyl residue the range is 137.0–140.2 ppm (in the nitro-
derivatives) and 117.5–119.0 ppm (in the amine-derivatives).
(5.80ppm) and H-3 (5.78ppm). Moreover, the correlation between
2
d-NOESY experiments performed on compound 25 (R
1
= Cl,
the nitrogen of the amino group (57.73 ppm) and the broad singlet
at 4.90 ppm, demonstrates that this signal corresponds to the
R
2
= Pr, X = S) show the existence of the NOE effects between the
aromatic H-6″ and the H-2′ of the linear chain, and vice versa. Also,
another NOE effect is observed between H-6″ and H-3′. These NOE
effects are compatible with the formation of an intra-molecular
hydrogen bond between the hydroxyl group of the C-3′ and the
amino group in 2″-position of the aromatic ring (Fig. 3).
protons of the amino group (―NH ). The HMBC experiment
2
confirms these assignments. Thus, the signal at 85.46 ppm corre-
lated with ―CH ―CH (m, 2.97 ppm) and with ―CH ―CH (t,
2
3
2
3
0.95 ppm) corresponds to N-3. Besides the correlation between
the peak at 81.59 ppm and the signal at 1.70ppm (H-2′) indicates
that this peak can be designed as N-1. Finally a correlation between
the signal at 57.73 ppm and the multiplet at 6.57ppm correspond-
ing to H-3″ determines the shift of the amino group (―NH2).
In a similar way, the chemical shift of nitrogens and their protons
in compound 30 were determined using the HSQC and HMBC
experiments (Table 7, Fig. 2). The correlations in this urea derivative
Acknowledgements
This work was partially supported by the Instituto de Salud Carlos III
through the grant FI11/00432.
are in concordance with the data observed in 26. Furthermore, in References
this case another correlation between the signal at 81.41ppm
and H-2′ (m, 1.68 ppm) confirms the assignment of N-1.
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[
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ureas previously synthesized by our research group,
by
[
[
[
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13
differences between the C chemical shifts of the previous
[15]
derivatives and the new hydroxypropylthioureas and ureas are
13
the C signals of the propyl chain (C-1′, C-2′ and mainly C-3′) and
the C-1″ of the aromatic ring. The C-1′ atom in the final hydroxypro-
pyl derivatives shows signals in range of 36.9–44.3ppm, whereas
for the oxopropyl compounds the range is 35.5–41.1 ppm; the
C-2′ atom in the first compounds appears between 38.5 and
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Magn. Reson. Chem. (2016)
Copyright © 2016 John Wiley & Sons, Ltd.
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