The determination of enantiomer composition of 1‐((3‐chlorophenyl)‐(phenyl)methyl) amine and 1‐((3‐chlorophenyl)(phenyl)‐methyl) urea (galodif) by nmr spectroscopy, chiral hplc, and polarimetry

Article abstract of DOI:10.1002/chir.23005

For the first time, a method for enantiomer resolution of the anticonvulsant Galodif (1‐((3‐chlorophenyl)(phenyl)methyl) urea) by chiral HPLC was developed, whereas the enantiomeric composition of 1‐((3‐chlorophenyl)(phenyl) methyl) amine—precursor in Galodif synthesis—cannot be resolved by this method. However, starting 1‐((3‐chlorophenyl)(phenyl)methyl) amine quantitatively forms diastereomeric N‐((3‐chlorophenyl)(phenyl)methyl)‐1‐ camphorsulfonamides in reaction with chiral (1R)‐(+)‐ or (1S)‐(?)‐camphor‐10‐ sulfonyl chlorides. The diastereomeric ratio of obtained camphorsulfonamides can be easily determined by NMR¹H and¹³C spectroscopy. The DFT calculations of specific rotation of Galodif enantiomers showed good agreement with experimental data. The absolute configuration of enantiomers was proposed for the first time.

Full text of DOI:10.1002/chir.23005

Received: 28 March 2018
DOI: 10.1002/chir.23005
Revised: 28 June 2018
Accepted: 9 July 2018
R E G U L A R A R T I C L E
The determination of enantiomer composition of
1
1
‐((3‐chlorophenyl)‐(phenyl)methyl) amine and
‐((3‐chlorophenyl)(phenyl)‐methyl) urea (Galodif)
by NMR spectroscopy, chiral HPLC, and polarimetry
1
1
1
Vera Yu. Kuksenok
| Victoria V. Shtrykova | Victor D. Filimonov |
2
3
1
Alexandr G. Druganov | Alexandr A. Bondarev | Ksenia S. Stankevich
1
The Kizhner Research Center, National
Abstract
Research Tomsk Polytechnic University,
Tomsk, Russia
For the first time, a method for enantiomer resolution of the anticonvulsant
2
N.N. Vorozhtsov Novosibirsk Institute of
Galodif (1‐((3‐chlorophenyl)(phenyl)methyl) urea) by chiral HPLC was devel-
oped, whereas the enantiomeric composition of 1‐((3‐chlorophenyl)(phenyl)
methyl) amine—precursor in Galodif synthesis—cannot be resolved by this
method. However, starting 1‐((3‐chlorophenyl)(phenyl)methyl) amine
quantitatively forms diastereomeric N‐((3‐chlorophenyl)(phenyl)methyl)‐1‐
camphorsulfonamides in reaction with chiral (1R)‐(+)‐ or (1S)‐(−)‐camphor‐10‐
sulfonyl chlorides. The diastereomeric ratio of obtained camphorsulfonamides
Organic Chemistry, Siberian Branch of the
Russian Academy of Sciences,
Novosibirsk, Russia
3
Altai State University, Barnaul, Russia
Correspondence
Vera Yu. Kuksenok, The Kizhner
Research Center, National Research
Tomsk Polytechnic University, 30 Lenin
Avenue, Tomsk 634050, Russia.
Email: kukver89@tpu.ru
1
13
can be easily determined by NMR H and C spectroscopy. The DFT
calculations of specific rotation of Galodif enantiomers showed good
agreement with experimental data. The absolute configuration of enantiomers
was proposed for the first time.
Funding information
Tomsk Polytechnic University Competi-
tiveness Enhancement Program, Grant/
Award Number: CEP – N. Kizhner
Center—213/2018
KEYWORDS
anticonvulsants, chiral analysis, chiral HPLC, Galodif, NMR spectroscopy, polarimetry, specific
rotation calculations
11
1
| INTRODUCTION
investigated.
These studies opened a prospect for
manufacturing a new generation of anticonvulsant drugs.
However, there are no methods for determination of
enantiomeric composition of Galodif 1 described to date.
The aim of this study was to develop the methods
for chiral analysis of the compound 1 and its precursor,
1‐((3‐chlorophenyl)(phenyl)methyl) amine 2. Galodif 1
can be easily prepared by reacting benzhydrylamine
2 with cyanate (Scheme 1). The reaction proceeds
without racemization. Because of the pronounced basic
properties, benzhydrylamine 2 can be separated into
Galodif 1 (1‐((3‐chlorophenyl)(phenyl)methyl) urea) is
an anticonvulsant with low toxicity and hepatoprotective
1
effect that is used to treat epileptic seizures and alcohol
2-5
addicton. Despite the fact that it is chiral, Galodif was
1-5
synthesized and investigated as racemate, although it is
known that usually, only one of a drug's enantiomers is
6-10
responsible for the desired pharmacological effect.
Recently, the enantiomerically enriched forms of
compound 1 have been obtained, and the relationship
between anticonvulsant activity and R‐ to S‐ratio has been
11,12
enantiomers by chiral acid agents.
Chirality. 2018;1–9.
wileyonlinelibrary.com/journal/chir
© 2018 Wiley Periodicals, Inc.
1

2
KUKSENOK ET AL.
Completion of reactions and purity of obtained
products were monitored by TLC (plates Silufol
UV‐254), eluent—toluene:ethanol (9:1).
SCHEME 1 Preparation of Galodif 1 from 1‐((3‐chlorophenyl)
(
phenyl)methyl) amine 2
2
2
.3 | Experimental procedures
.3.1 | Synthesis of 1‐((3‐chlorophenyl)
2
2
| MATERIALS AND METHODS
.1 | Chemicals, reagents
(phenyl)(methyl) urea 1 (Galodif)
3‐Cl‐benzhydrylamine 2 (5.30 g [14 mmol]) was dissolved
in ethanol (30 mL), and 0.43‐mL HCl (14 mmol) was added.
Reaction mixture was stirred for 10 minutes at 20°С. The
completion of the amine hydrochloride formation was
monitored by TLC. Then aqueous sodium cyanate (1.10 g
The commercially available reagents and solvents
having reagent grade for synthesis and analytical grade
for HPLC and NMR analysis were purchased from
Sigma‐Aldrich and used without further purification.
[16.8 mmol] in 24‐mL H O) was added. The resulting
2
3
‐Cl‐benzhydrylamine 2 and (1R)‐(+)‐ and (1S)‐(−)‐cam-
mixture was stirred for 1 hour at 20°С. The end of the
phor‐10‐sulfonyl chlorides 3a,b were synthesized as
previously described.
reaction was controlled by TLC. After the completion of
13,14
the reaction, 30‐mL H O was added and the precipitate
2
of Galodif 1 was collected by filtering and dried on air.
2
.2 | Instrumentation
1
‐((3‐Chlorophenyl)(phenyl)methyl) urea 1
1
13
Yield 90%, purity 99% (by HPLC). White crystals, mp
1
NMR Н and С spectra were recorded on spectrometer
Bruker AVANCE III HD (400 MHz) using TMS as inter-
nal standard and DMSO‐d and CDCl3 as solvents.
NMR Н and C spectra were recorded at 400 and
1
37°С to 138°С, H NMR (400 MHz, DMSO‐d , δ): 5.62
6
(
s, 2H, NH ), 5.89 (d, J = 8.7 Hz, 1H, CH), 7.06 (d,
2
6
1
3
1
13
J = 8.7 Hz, 1H, NH), 7.21 to 7.38 (m, 9H, Ar). С NMR
75 MHz, DMSO‐d , δ): 56.4, 127.0, 128.5, 129.7, 132.5,
(
1
1
00 MHz, respectively. Samples of 20 mg dissolved in 1 mL
6
42.3, 146.0, 157.2.
of deuterated solvent were measured using 5‐mm probe.
NMR Н parameters: zg30 pulse sequence, 4.1‐seconds
acquisition time; 1‐second relaxation delay. NMR
parameters: zgpg30 pulse sequence; 1.4‐seconds acquisi-
tion time; 2‐seconds relaxation delay.
1
13
C
2
.3.2 | Synthesis of sulfonamides 4a,b
3‐Cl‐benzhydrylamine (0.22 g, 1 mmol), methylene
Chiral HPLC analysis was conducted using high perfor-
mance liquid chromatographer Agilent 1200 Compact LC
equipped with UV detector. Chiral chromatographic col-
umn Agilent Ultron ES‐OVM‐C (150 × 4.6 mm, ID, 5 μ)
equipped with guard column (contained the same sorbent
as analytical column) was used as a stationary phase. The
following eluting conditions were applied: mobile phase
MeCN‐phosphate buffer (0.02M, pH 4.4) in ratio of 1:9
chloride (2 mL), and Et N (0.21 mL, 1.5 mmol) were
3
charged at two‐necked flask equipped with dropping
funnel and condenser with a calcium chloride tube at
the top. The reaction mixture was cooled to 0°С, and
the chiral camphor sulfochloride 3a (or 3b) (0.37 g
[1.5 mmol] dissolved in 5‐mL methylene chloride) was
added dropwise during 10 minutes. The mixture was
stirred for 30 minutes at 0°С and then heated for
30 minutes at 40°С. The completion of the reaction was
monitored by TLC. The solvent was evaporated, 40‐mL
(isocratic elution); flow rate (1 mL/min), temperature of
the column (30°C); sample volume (10 μL), sample concen-
tration (40%; Galodif solution in MeCN‐phosphate buffer
H O was added to the residue, and the white crystals
2
1
:9); and UV‐detection at 200 nm. The main chromato-
were filtered, washed on filter with H O, and dried on air.
2
graphic parameters, such as resolution (R = 2[t − t ]/
S
2
1
[
w + w ], where t , t are the retention times and w , w
2
N‐((3‐Chlorophenyl)(phenyl)methyl)‐(1S)‐(+)‐
1
2
1
2
1
are the peak widths at the baseline) and selectivity factor
α = k /k , where k is the retention factor and k = [t − t ]/
camphorsulfonamide 4a
Yield 88%. White crystals, mp 100°С to 103°С, H NMR
1
(
2
1
0
t0), were calculated according to given formulae.
(400 MHz, CDCl ): δ, ppm = 0.47 (s, 1.5H, (S)(S)‐CH ),
3
3
Optical rotations were determined on automatic
polarimeter ATAGO POL 1/2. The analysis was
conducted in following conditions: 598 nm; solvent,
ethanol; concentration of samples, 5%; temperature,
0.60 (s, 1.5H, (R)(S)‐CH ), 0.83 (s, 1.5H, (S)(S)‐CH ), 0.86 (s,
3
3
1.5H, (R)(S)‐CH ), 1.26 to 1.39 (m, 1H, CH ), 1.75 to 2.06
3
2
(m, 5H, CH , СН), 2.31 to 2.36 (m, 1Н, СН), 2.75 to 2.79
2
(m, 2H, CH ‐SO ), 5.74 to 5.81 (m, 1H, CHAr ), 6.76 to 6.78
2
2
2
2
0°C; and length of optical route, 100 mm.
(d, J = 9.3, 0.5H, (R)(S)‐NH), 6.85 to 6.87 (d, J = 9.3, 0.5H,

KUKSENOK ET AL.
3
1
3
(
S)(S)‐NH), 7.24 to 7.33 (m, 9H, Ar). С NMR (75 MHz,
We have made attempts for the separation of race-
mates 1 and 2 by HPLC method on two types of chiral
columns: Agilent Ultron ES‐Pepsin (A) and Agilent
CDCl ): δ, ppm = 19.20, 19.25, 19.65, 19.72, 27.85, 28.01,
2.69, 42.72, 42.98, 43.02, 59.74, 59.79, 61.25, 61.43, 127.59,
27.75, 134.42, 134.85, 140.26, 140.45, 143.11, 143.40.
3
4
1
25-29
Ultron ES‐OVM‐C (B),
each featuring different
composition of chiral sorbent. Column А contained
pepsin protein mounted onto silica gel particles, whereas
column B contained ovomucoid protein.
N‐((3‐Chlorophenyl)(phenyl)methyl)‐(1R)‐(−)‐
camphorsulfonamide 4b
Yield 84%. White crystals, mp 100°С to 102°С, H NMR
1
The enantiomeric resolution of 1 and 2 racemates on
column А was not accomplished. Various separation
parameters were tried out such as the buffer pH
(within acceptable range of 4 to 6), composition of mobile
phase (content of the solvent in the buffer is within
acceptable range of 0 to 10%, solvents tested: MeCN,
MeOH, EtOH), elution modes (isocratic, gradient),
time of analysis (from 10 to 60 min). In each case, broad
but inseparable peaks for the 1 and 2 racemates were
observed in HPLC chromatograms.
(
400 MHz, CDCl , δ): 0.46 (s, 1.5H, (R)(R)‐CH ), 0.58
3
3
(
s, 1.5H, (S)(R)‐CH ), 0.81 (s, 1.5H, (R)(R)‐CH ), 0.84
3
3
(
s, 1.5H, (S)(R)‐CH ), 1.21 to 1.26 (m, 1H, CH ), 1.80 to
3
2
1
.88 (m, 1H, CH ), 1.98 to 2.08 (m, 5H, CH , СН), 2.79
2
2
to 2.85 (d, 2H, CH ‐SO ), 4.07 to 4.14 (m, 1H), 5.73 to
2
2
5
.79 (m, 1H, CHAr ), 6.79 to 6.81 (d, J = 9.3, 0.5H, (S)
2
(
R)‐NH), 6.88 to 6.90 (d, J = 9.3, 0.5H, (R)(R)‐NH), 7.22
to 7.37 (m, 9H, Ar).
The separation parameters that ensured a good
resolution of racemate 1 on column B were found.
Figure 1 shows that the difference in the retention time
of Galodif enantiomers was 2 minutes. The study of
enantiomerically enriched Galodif samples demonstrated
that (−)‐1 had shorter retention time (11.7 min), while
2
.4 | Quantum calculations
For the conformational search of (S)‐Galodif, Jaguar
software (version 7.6, Schrödinger, LLC, New York,
New York, 2009) was used. The structure of conformers
was optimized twice. The first optimization was
performed using density functional theory (DFT) at
B3LYP/6‐311G level of theory. Then the conformers with
the lowest energy (population > 0.5%) were found and
optimized at B3LYP/aug‐cc‐PVDZ level of theory. The
solvation effect of ethanol was considered by using the
conductor‐like screening (COSMO) polarizable contin-
uum model. For structure optimizations and specific
(
+)‐1 had longer retention time (13.7 min) under the used
conditions. At the chosen separation parameters, the
resolution (R ) was 3.02 (>1.5), and the selectivity factor
S
(α) was 1.20.
15
rotations calculations, the ORCA program was applied.
The population of conformers was calculated using
Boltzmann distribution.
3
3
| RESULTS AND DISCUSSION
.1 | Chiral HPLC analysis of
benzhydrylurea 1 and benzhydrylamine 2
Enantiomeric separation can be performed using various
16-22
2
0
approaches.
Among them, the HPLC analysis on
FIGURE 2 The specific rotation [α]
D
(c = 5%, in ethanol) over
chiral stationary phase is the most commonly used
one.
enantiomeric composition of (+)‐1‐((3‐chlorophenyl)(phenyl)
methyl) urea 1
1
6-18,23,24
FIGURE 1 HPLC of racemic Galodif 1 using chiral column ES‐OVM‐C (B)

4
KUKSENOK ET AL.
At the same time, the enantiomeric resolution of
more polar benzhydrylamine 2 was not achieved on both
columns A and B.
Thus, it was found that it is possible to determine
enantiomeric composition of 1‐((3‐chlorophenyl)(phe-
nyl)methyl) urea 1, but not benzhydrylamine 2, using
HPLC method with chiral column Agilent Ultron ES‐
OVM‐C. The discovered method is the first example of
chiral HPLC resolution of benzhydrylureas. Further
studies on these aspects will be reported later.
3
.2 | Analysis of the enantiomeric
SCHEME 2 Conformational options of Galodif structure
composition of Galodif 1 by polarimetry
and the specific rotation quantum
calculation
We conducted polarimetric study of Galodif 1 enantio-
1
1
meric mixtures obtained as previously described and
containing different ratio of enantiomers determined by
HPLC on Agilent Ultron ES‐OVM‐C column. It was
found that there is a linear relation between specific
20
rotation ([α]D ) and amount of the dominant enantiomer
in a composition (x), in which enantiomer content does
not exceed 87% (Figure 2). This relation complies with
correlation Equation 1:
FIGURE
energy conformers of (S)‐Galodif 1 (aug‐cc‐PVDZ level; solvent,
ethanol; solvating model, COSMO)
3
Structures and population (in %) of lowest
2
D
0
2
½αꢀ ¼ 0:70x−35:57; R ¼ 0:97
(1)
–
2
0
FIGURE 4 The specific rotation [α] (in ethanol) of (S)‐Galodif, calculated at B3LYP/aug‐cc‐PVDZ level of theory at different wavelength
using conductor‐like polarizable continuum model

KUKSENOK ET AL.
5
Extrapolation of specific rotation to 100% content of
the dominant enantiomer 1 allows to define value [α]D
of this enantiomer as +34.50 (Equation 1).
between simulated and experimental data, we supposed
the configuration of (+)‐ and (−)‐Galodif as (S)‐ and
(R)‐enantiomers, respectively.
20
Thus, polarimetry can be a simple and quick method
for determination of enantiomeric composition of
benzhydrylurea 1 using Equation 1. Furthermore, the
obtained results allowed to predict the approximate
value of specific rotation of (S)‐(+)‐ and (R)‐(−)‐enantio-
mers, which have not been produced as individual
enantiomers yet.
As shown on Scheme 2, there are four flexible bonds
in Galodif structure, defining the conformational options
for this molecule.
3
.3 | Chiral analysis of 1‐((3‐chlorophenyl)
(
(
phenyl)methyl) amine 2 by NMR using
1R)‐(+)‐ or (1S)‐(−)‐camphorsulfonyl
chlorides
7Since we could not resolve the 1‐((3‐chlorophenyl)(phe-
nyl)methyl) amine 2 enantiomers using chiral HPLC, we
tried the other approach. For the first time, we have
obtained two diastereomeric sulfonamides 4a,b from
benzhydrylamine 2 and (1R)‐(+)‐ or (1S)‐(−)‐camphor‐
10‐sulfonyl chlorides 3a,b according to the Scheme 3.
For this purpose, we used enantiomerically enriched
forms of amine 2 obtained as described in Patent Applica-
tion with (+)‐e.e. and (−)‐e.e. of 24% (e.e. was deter-
mined by chiral HPLC of benzhydrylureas 1 derived
from the given samples of amine 2 as specified in
Section 1). It is known that in some cases, NMR
spectra of covalent diastereomers may vary significantly,
which allows to analyze quantitative composition of
We conducted the conformational search for (S)‐
30
enantiomer of Galodif using Jaguar software. As a
result, 52 conformers of (S)‐1 were found. The further
optimization at the B3LYP/6‐311G level of theory
demonstrated that conformers converged to 12 struc-
tures, and four of them had too low population (less than
11
0
.5%). Thus, only eight stable conformers of (S)‐Galodif
were used in further calculations. The geometry optimi-
zation and specific rotation of these eight conformers
were computed at B3LYP/aug‐cc‐PVDZ level of theory
in ethanol (conductor‐like screening [COSMO] polariz-
able continuum model) (Figure 3). The relative abun-
dances of the conformers were determined using
Boltzmann distribution. The total specific rotation of
2
0
(
S)‐Galodif was calculated. The [α]D value (in ethanol)
found by using the polarizable continuum model was
48.09, whereas the conductor‐like polarizable contin-
uum model predicted specific rotation of (S)‐enantiomer
+
20
31-39
[
α]D (in ethanol) to be +39.98, which is close
to the
value found according to Equation 1 (+34.5 for EtOH). It
20
is known that the [α]D calculated for molecules with
small rotation ([α] < 100) can significantly deviate from
D
experimental values and even have the incorrect
31,32
sign.
However, the use of appropriate solvation
model can significantly increase the accuracy of
33,34
calculations.
In our case, conductor‐like polarizable
continuum model reduced the difference between the
calculated and experimental data. Moreover, we
calculated specific rotations of (S)‐Galodif at different
wavelength (Figure 4), and the values had the positive
sign in all cases. Because of the satisfied agreement
1
FIGURE 5 NMR H spectrum of diastereomeric sulfonamide 4a
(d.e. 24%) in CDCl : Resolution of signals of NH‐group (left) and
two CH ‐groups (right)
3
3
SCHEME 3 Acylation of
benzhydrylamine 2 by camphor
sulfochlorides 3a,b

6
KUKSENOK ET AL.
4
0-43
diastereomeric mixtures.
Thus, we were expecting to
sulfonamides 4a,b in СDСl3. In DMSO‐d6 NH,
signals of both diastereomers did not resolve and
appeared as one doublet at 8.48 ppm. Apparently, it is
caused by the proton exchange course. At the
same time, the resolution of diastereotopic signals of
СН ‐SO (doublets 2.99 and 3.05 ppm) and one of СН
group (singlets 0.56 and 0.58 ppm) was observed in Н
NMR spectrum of sulfonamide 4a in DMSO. However,
it was not enough for accurate integral intensities
determination.
measure the relative content of 4a and 4b in diastereo-
meric composition using NMR. We observed the signal
doubling of NH and CH groups of both diastereomers
3
1
in Н NMR spectrum of 4a,b diastereomeric mixture
Figure 5). The integral relation of these signals was
equal to the ratio of enantiomers in the original
benzhydrylamine 2 (Table 1).
It was found that the discovered diastereomeric
differences are typical only for Н NMR spectra of
(
2
2
3
1
1
1
TABLE 1 Characteristics of Н NMR spectra of diastereomeric sulfonamides 4a,b
1
Chemical Shifts of Н NMR, ppm
Ratio of
Amine
Signals of
NH Group
Signals of
CH Group
Isomers
(+)‐2: (−)‐2
Diastereomers
Isomer 3
3
a
4
a
3a (R)‐(+)
(R)(S)‐(+)(+)
(S)(S)‐(−)(+)
6.85–6.87 d
(R)(S)‐(+)(+)
0.60 s
(S)(S)‐(−)(+)
0.47 s
64:36
b
6
.76–6.78 d
(R)(R)‐(+)(−)
.88‐6.90 d
37:63
b
4
b
3b (S)‐(−)
(S)(R)‐(−)(−)
6.79‐6.81 d
(R)(R)‐(+)(−)
0.46 s
(S)(R)‐(−)(−)
0.58 s
36:64
6
a
Synthesized from (S)‐(+)‐enantiomerically enriched amine 2.
b
Synthesized from (R)‐(−)‐enantiomerically enriched amine 2.
1
3
FIGURE 6
С NMR spectrum of diastereomeric sulfonamide 4a in CDCl
3

KUKSENOK ET AL.
7
It was also demonstrated that similar carbon atoms of
camphor‐10‐sulfonyl chlorides 3a,b is their high solubil-
ity, which is important for accurate determination of
signal intensities in NMR spectra.
13
diastereomeric mixture 4a,b in С NMR spectra had
slightly different chemical shifts (Figure 6, Table 2,
Scheme 4).
It is significant that the integral intensities ratios of
similar carbon atoms of diastereomers in compound 4a
are the same as those determined by Н NMR (Table 1),
4
| CONCLUSION
1
The determination of enantiomeric purity is the
important part of the chiral drug development. Therefore,
the first method for quantitative determination of
enantiomeric excess of anticonvulsant Galodif by
chiral HPLC was discovered. The proposed correlation
equation between enantiomeric composition and specific
and consistent with HPLC data.
1
13
Therefore, Н and
С NMR spectroscopy is a
convenient method for quantitative determination of
enantiomeric composition of 1‐((3‐chlorophenyl)(phe-
nyl)methyl) amine 2 by recording NMR spectra of
diastereomeric camphor sulfonamides 4a,b. It was shown
that concentration in a range from 10 to 30 mg/mL did
rotation of Galodif allowed to quantify [α] of pure enan-
D
tiomers of this compound and also could be applied for
rapid e.e. determination of benzhydrylurea 1 by polarim-
etry. As a result of conformer analysis and specific rota-
tion quantum calculation, absolute configuration of (+)‐
and (−)‐Galodif was proposed as (S)‐ and (R)‐enantio-
mers, respectively. Furthermore, the simple protocol for
chiral analysis of Galodif precursor benzhydrylamine 2
1
13
not influence the chemical shifts in NMR Н and
and enantiomers ratio. (1R)‐(+)‐ and (1S)‐(−)‐camphor‐
0‐sulfonic acids are commercially available and cheap
reagents, which can be easily converted to the corre-
C
1
1
4
sponding sulfochlorides 3a,b in mild conditions.
Chiral camphor‐10‐sulfonyl chlorides 3a,b demonstrated
excellent resolving properties, high reactivity, and
stability at storage in comparison with acid halides
derivatizing agents. The additional advantage of chiral
1
13
by NMR Н and C was developed. The diastereomeric
camphor sulfonamides 4a,b demonstrated good resolu-
tion in NMR spectra, and the satisfactory results in diaste-
reomeric ratio evaluation of 4a,b were obtained.
1
3
TABLE 2 Chemical shifts of С NMR of diastereomeric sulfon-
amide 4a in CDCl
3
ACKNOWLEDGMENTS
Ratio of signals
a
Carbon Atom Number
δ, ppm
(+)(−): (+)(+), %
The research was supported from Tomsk Polytechnic
University Competitiveness Enhancement Program grant
no. CEP – N. Kizhner Center—213/2018.
1
1
1
2
8
4
143.11 143.40 35:65
140.45 140.26 34:66
134.85 134.42 36:64
127.75 127.59 36:64
ORCID
CH, Ar
1
5
1
6
8
1
1
1
61.25
59.74
43.02
42.72
27.85
19.65
19.25
61.43 37:63
59.79 39:61
42.98 36:64
42.69 35:65
28.01 36:64
19.72 37:63
19.20 37:63
Vera Yu. Kuksenok http://orcid.org/0000-0003-1463-6387
0
REFERENCES
1
. Filimonov VD, Bakibaev AA, Pustovoitov AV, et al.
Quantitative relationship between anticonvulsant activity in
N‐benzhydrylamides and N‐benzhydrylureas, their structures,
or 9
or 2
or 2
1
3
and C NMR spectra. Pharm Chem J. 1988;22(5):358‐363.
2
. Shushpanova TV, Bokhan NA, Lebedeva VF, et al. Treatment
of alcoholic patients using anticonvulsant urea derivative influ-
ences the metabolism of neuro‐active steroid hormones—the
system of stress markers. Addiction Research and Therapy.
a
See Scheme 4.
2016;7:271‐276.
3
. Shushpanova TV, Solonskii AV. Synaptogenesis and the forma-
tion of benzodiazepine receptors in the human brain in
conditions of prenatal alcoholization. Neurosci Behav Physiol.
2013;43(4):423‐430.
4
. Novozeeva TP, Akhmedzhanov RR, Saratikov AS, Bakibaev AA,
Filimonov VD, Pustovoitov AV. Amide‐ and urea‐based syn-
thetic anticonvulsants, antihypoxics, and inducers of the
SCHEME
4
Crbon atom numbers of diastereomeric
sulfonamides 4a,b

8
KUKSENOK ET AL.
hepatic monooxygenase system. 8. Effect of benzhydrylureas
and m‐clorobenzhydrylureas on the rat liver mono oxygenase
system. Pharm Chem J. 1993;27(6):398‐401.
24. Gübitz G, Schmid MS. Chiral separation by chromatographic
and electromigration techniques. A review. Biopharm Drug
Dispos. 2001;22(7‐8):291‐336.
5
. Bakibaev AA, Akhmedzhanov RR, Novozheeva TP, et al.
Amide‐ and urea‐based synthetic anticonvulsants, antihypoxics,
and inducers of the hepatic monooxygenase system. 7. Effect of
benzhydrylureas on the cytohrome P‐450‐dependent liver
monooxygenase system. Pharm Chem J. 1993;27(6):395‐397.
25. Ferretti R, Zanitti L, Cirilli R. Development of an HPLC method
for the simultaneous determination of chiral impurities and
assay of (S)‐Clopidogrel using a cellulose‐based chiral stationary
phase in methanol/water mode. J Sep Sci. 2017. https://doi.org/
10.1002/jssc.201701191;41(6):1208‐1215.
6
. Brooks WH, Guida WC, Daniel KG. The significance of chirality
in drug design and development. Curr Top Med Chem.
26. Ali I, Hussain I, Sanagi MM, Aboul‐Enein HY. Chiral separation
of some classes of pesticides by HPLC method. In: Analytical
Separation Science. New York: Wiley; 2015:321‐370.
2
011;11(7):760‐770.
. Agrawal YK, Bhatt HG, Raval HG, Oza PM, Gogoi PJ. Chirality
new era of therapeutics. Mini Rev Med Chem.
007;7(5):451‐460.
7
27. Sharp VS, Risley DS, Oman TJ, Starkey LE. Evaluation of an
HPLC chiral separation flow scheme for small molecules. J Liq
Chromatogr Related Technol. 2008;31(5):629‐666.
—
a
2
8
. Testa B. Types of stereoselectivity in drug metabolism: a heuris-
tic approach. Drug Metab Rev. 2015;47(2):239‐251.
2
8. Millot MC. Separation of drug enantiomers by liquid chroma-
tography and capillary electrophoresis, using immobilized
proteins as chiral selectors. J Chromatogr B. 2003;797(1‐2):
9
. Smith SW. Chiral toxicology: it's the same thing … only differ-
ent. Toxicol Sci. 2009;110(1):4‐30.
131‐159.
1
0. Eichelbaum M, Gross AS. Stereochemical aspects of drug action
and disposition. Adv Drug Res. 1996;28:1‐64.
29. Haginaka J. Protein‐based chiral stationary phases for
high‐performance liquid chromatography enantioseparations.
J Chromatogr a. 2001;906(1‐2):253‐273.
1
1. Hudoley VN, Doroshenko AS, Filimonov VD, Shtrykova VV,
Kuksionok VY. Patent Application US 2016/0244404 A1. Russia:
Sintegal; 2016.
30. Bochevarov AD, Harder E, Hughes TF, et al. Jaguar: a
high‐performance quantum chemistry software program with
strengths in life and materials sciences. Int J Quantum Chem.
1
2. Kashima K, Sakamoto Y, Ohta Y, Kawanishi K, Takemura K,
Takemura Y. Patent US 6172228 B1. Japan: Azwell Inc.; 2001.
2013;113(18):2110‐2142.
3
1. Stephens PJ, McCann DM, Cheesman JR, Frisch MJ. Determi-
nation of absolute configurations of chiral molecules using ab
initio time‐dependent density functional theory calculations of
optical rotation: how reliable are absolute configurations
obtained for molecules with small rotations? Chirality.
1
3. Ho B, Cridera AM, Stables JP. Synthesis and structure—activity
relationships of potential anticonvulsants based on 2‐
piperidinecarboxylic acid and related pharmacophores. Eur J
Med Chem. 2001;36(3):265‐286.
1
4. Xiao D, Hu J, Zhang M, Li M, Wanga G, Yao H. Synthesis and
characterization of camphorsulfonyl acetate of cellulose.
Carbohydr Res. 2004;339(11):1925‐1931.
2005;17(S1):S52‐S64.
3
3
2. Liao T‐G, Ren J, Fan H‐F, Xie M‐J, Zhu H‐J. Study of syntheses
and specific rotations of (S)‐3‐phenylhexan‐3‐ol and its deriva-
tives. Tetrahedron: Asymmetry. 2008;19(7):808‐815.
1
1
1
1
1
5. Neese F. The ORCA program system. WIREs Comput Mol Sci.
2
012;2(1):73‐78.
6. Ward TJ, Ward KD. Chiral separations: fundamental review
010. Anal Chem. 2010;82(12):4712‐4722.
3. Aharon T, Lemler P, Vaccaro PH, Caricato M. Comparison of
measured and predicted specific optical rotation in gas and
solution phases: a test for the polarizable continuum model of
solvation. Chirality. 2018;30(4):383‐395.
2
7. Izake EL. Chiral discrimination and enantioselective analysis of
drugs: an overview. J Pharm Sci. 2007;96(7):1659‐1676.
3
4. Mennucci B, Cappelli C, Cammi R, Tomasi J. Modeling solvent
effects on chiroptical properties. Chirality. 2011;23(9):717‐729.
8. Busch KW, Busch MA (Eds). Chiral analysis. Elsevier Science;
2
006.editors
3
5. Mort BC, Autschbach J. Temperature dependence of the
optical rotation in six bicyclic organic molecules calculated by
vibrational averaging. Chemphyschem. 2007;8(4):605‐616.
9. Yua X, Yao Z‐P. Chiral recognition and determination of enan-
tiomeric excess by mass spectrometry: a review. Anal Chim
Acta. 2017;968:1‐20.
3
3
3
6. McCann DM, Stephens PJ. Determination of absolute configura-
tion using density functional theory calculations of optical
rotation and electronic circular dichroism: chiral alkenes.
J Org Chem. 2006;71(16):6074‐6098.
2
0. Feng L, Bian X, Chen Z, et al. Determination of D‐lactide
content in lactide stereoisomeric mixture using gas chromatog-
raphy‐polarimetry. Talanta. 2017;164:268‐274.
2
1. Patterson D, Doyle JM. Sensitive chiral analysis via microwave
three‐wave mixing. Phys Rev Lett 2013;111:1–5, 2.
7. Giorgio E, Roje M, Tanaka K, et al. Determination of the
absolute configuration of flexible molecules by ab initio ORD
calculations: a case study with cytoxazones and isocytoxazones.
J Org Chem. 2005;70(17):6557‐6563.
2
2. Yun Y, Gellman AJ. Adsorption‐induced auto‐amplification
of enantiomeric excess on an achiral surface. Nat Chem.
2
015;7(6):520‐525.
8. Stephens PJ, McCann DM, Devlin FJ, Cheeseman JR, Frisch MJ.
Determination of the absolute configuration of [32](1,4)
barrelenophanedicarbonitrile using concerted time‐dependent
density functional theory calculations of optical rotation
2
3. Cavazzini A, Pasti L, Massi A, Marchetti N, Dondi F. Recent
applications in chiral high performance liquid chromatography:
a review. Anal Chim Acta. 2011;706(2):205‐222.

KUKSENOK ET AL.
9
and electronic circular dichroism. J Am Chem Soc. 2004;
43. Zhao Y, Swager TM. Simultaneous chirality sensing of multiple
1
26(24):7514‐7521.
amines by 19F NMR. J Am Chem Soc. 2015;137(9):3221‐3224.
3
4
4
4
9. Wenzel TJ, Willcox JD. Chiral reagents for the determination of
enantiomeric excess and absolute configuration using NMR
spectroscopy. Chirality. 2003;15(3):256‐270.
How to cite this article: Kuksenok VY,
Shtrykova VV, Filimonov VD, Druganov AG,
Bondarev AA, Stankevich KS. The determination of
enantiomer composition of 1‐((3‐chlorophenyl)‐
0. Wenzel TJ, Chisholm CD. Using NMR spectroscopic methods to
determine enantiomeric purity and assign absolute stereochem-
istry. Prog Nucl Magn Reson Spectrosc. 2011;59(1):1‐63.
(
(
phenyl)methyl) amine and 1‐((3‐chlorophenyl)
phenyl)‐methyl) urea (Galodif) by NMR
1. Silva MS. Recent advances in multinuclear NMR spectroscopy
for chiral recognition of organic compounds. Molecules.
spectroscopy, chiral HPLC, and polarimetry.
Chirality. 2018;1–9. https://doi.org/10.1002/
chir.23005
2
017;22(2):247‐268.
2. Nardini V, Palaretti V, Silva GVJ. Enantiomeric quantification of
amines by 1H and 13C NMR: first report of S‐citronellal as chiral
derivatization agent (CDA). Microchem J. 2017;133:208‐215.