Antibacterial activity of 5-dialkylaminomethylhydantoins and related compounds

Article abstract of DOI:10.1248/cpb.58.1123

To find new antibacterial leads in the class of hydantoin derivatives, we carried out synthetic investigation and biological evaluation of the title hydantoin derivatives and related compounds. Among the hydantoin derivatives described in this article, compound 3o, in which a 2,6-dichlorophenyl ring was introduced at the N-3 position of the hydantoin nucleus, showed the highest levels of antibacterial activity against both Escherichia coli NBRC14237 (NIHJ) and Staphylococcus aureus ATCC6538P (gram-negative and gram-positive bacteria, respectively) strains.

Full text of DOI:10.1248/cpb.58.1123

August 2010
Note
Chem. Pharm. Bull. 58(8) 1123—1126 (2010)
1123
Antibacterial Activity of 5-Dialkylaminomethylhydantoins and Related
Compounds
Fumiko FUJISAKI, Kaori SHOJI, Mari SHIMODOUZONO, Nobuhiro KASHIGE, Fumio MIAKE, and
Kunihiro SUMOTO*
Faculty of Pharmaceutical Science, Fukuoka University; Nanakuma, Jonan-ku, Fukuoka 814–0180, Japan.
Received May 20, 2010; accepted May 31, 2010; published online June 2, 2010
To find new antibacterial leads in the class of hydantoin derivatives, we carried out synthetic investigation
and biological evaluation of the title hydantoin derivatives and related compounds. Among the hydantoin deriva-
tives described in this article, compound 3o, in which a 2,6-dichlorophenyl ring was introduced at the N-3 posi-
tion of the hydantoin nucleus, showed the highest levels of antibacterial activity against both Escherichia coli
NBRC14237 (NIHJ) and Staphylococcus aureus ATCC6538P (gram-negative and gram-positive bacteria, respec-
tively) strains.
Key words hydantoin; 2-thiohydantoin; methylenehydantoin; b-aminoalanine; cyclization; antibacterial activity
In connection with our synthetic studies in the search for study has both donor and acceptor groups for hydrogen
new bioactive lead compounds, some molecular modifica- bonding in supramolecular interactions.6—8) From this point
tions of b-aminoalanines to the class of oxazolidinones (line- of view, further molecular modifications of this class of com-
zolid mimetic molecules) have been reported.1,2) Some of the pounds (B) seemed to be interesting in the search for new
synthesized compounds were evaluated for antibacterial antibacterial leads. We therefore carried additional synthetic
activity with gram-negative (Escherichia coli) and gram-pos- investigation and biological evaluation of these 5-dialkyl-
itive (Staphylococcus aureus) strains, and we found that most aminomethylhydantoin derivatives (B).
of the 4-dialkylaminomethyloxazolidinone-related deriva-
In this article, additional synthetic applications of b-
tives (A)1) showed no significant antibacterial activities aminoalanines9—11) to some new hydantoins and biological
against either gram-positive or gram-negative strains. There- evaluation of the hydantoin-related derivatives for antibacter-
fore, we carried out further molecular modification of line- ial activity with gram-negative (E. coli) and gram-positive (S.
zolid to the hydantoin analogue (B). Molecular modification aureus) strains are described.
to the represented structure (B) can be considered to be a
bioisosteric replacement3) of the oxazolidinone ring in line- (3) and Related Compounds In our synthetic studies on
zolid by a hydantoin nucleus (Fig. 1).
b-aminoalanines (1),9) we have already reported target mole-
Synthesis of 5-Dialkylaminomethyl-3-aryl-hydantoins
Through our pre-screening, we found that some hydantoin cules of 5-dialkylaminomethyl-3-aryl-hydantoins (3) which
derivatives in this class showed significant antibacterial activ- are easily prepared by cyclization of urea derivatives (2)
ities against both gram-negative (E. coli) and gram-positive readily obtained by addition of b-aminoalanines to aryliso-
(S. aureus) strains. In the early stage of invasion of bacteria cyanates (or arylisothiocyanates).10,11) The hydantoin deriva-
such as E. coli, the surface glycans of bacteria recognize host tives (3) described in this paper were prepared in a manner
cell lectin.4) For such molecular recognition of glycans, the similar to that reported previously. Synthesis of the com-
major recognition patterns between the host and target guest pounds (2, 3a, 3b, 3d—3j, 3n, 3p—3t, 4, 5) has already
molecules are through intermolecular hydrogen bonding in- been reported.10,11) Preparation of new derivatives (3c, 3k—
teractions. This interaction process is a logical path and is 3m, 3o) and their physical and spectroscopic data are
thought to direct a controlled biological response.5) We have described in the Experimental. The overall reaction stages
been interested in target compounds that interfere with such (1→2→3) for the target 5-dialkylaminomethyl-3-aryl-hydan-
a recognition process in order to find new leads. In terms of toins (3) are shown in Chart 1. The structures of compounds
donor-acceptor for hydrogen bondings, compound B has both (3) and the results of antibacterial assays are summarized in
donor and acceptor functionalities in the molecules, in con- Tables 1 and 2.
trast to molecule A having no donor for hydrogen bonding.
Assays for Antibacterial Activity and Discussion We
Bioactive linezolid (R1ϭH, and R2ϭCOCH3) as a lead in this used gram-negative bacteria (E. coli) and gram-positive bac-
Fig. 1. Structures of A, B and Linezolid
∗ To whom correspondence should be addressed. e-mail: kunihiro@adm.fukuoka-u.ac.jp
© 2010 Pharmaceutical Society of Japan

1124
Vol. 58, No. 8
Reaction conditions: a) 3 N-NaOH aq, rt—50 °C, 1—3 h. b) Concentarated HCl for several days, rt.
Chart 1
Table 2. Antibacterial Activities of Compounds 2, 4 and 5
Table 1. Antibacterial Activities of Compounds 3a—3t
Antibacterial activitya)
MIC (mmol/ml)
Compd.
E. coli
S. aureus
2a
2b
4a
4b
5
0.098
0.051
0.170
Ͼ0.627
0.340
0.394
0.205
0.340
Ͼ0.627
0.340
Antibacterial activitya)
Compd.
X
Y
R3
MIC (mmol/ml)
E. coli
S. aureus
3a
3b
3c
3d
3e
3f
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
S
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
N
H
H
0.411
0.195
0.177
0.207
0.217
0.229
0.119
0.048
0.105
0.207
0.197
0.204
0.171
0.088
0.044
0.085
Ͼ0.373
Ͼ0.393
Ͼ0.414
Ͼ0.367
0.411
0.391
0.355
0.414
0.433
0.458
0.237
0.097
0.210
0.414
0.393
0.408
0.171
0.088
0.088
0.085
Ͼ0.373
Ͼ0.393
Ͼ0.414
Ͼ0.367
a) We used Staphylococcus aureus ATCC6538P and E. coli NBRC14237 (NIHJ) as
target organisms.
H
teria (S. aureus) as target organisms for the assay of antibac-
terial activities of the synthesized hydantoin derivatives (3).
The bioassay for antibacterial activity was carried out by
authentic methods according to the Japanese Society of
Chemotherapy.12,13) Synthetic target compounds (3) were dis-
solved in dimethyl sulfoxide (DMSO) for bioassay. The min-
imum inhibitory concentrations (MICs) of the compounds
are summarized in Tables 1 and 2. Most of these compounds
showed remarkable antibacterial activity against both E. coli
and S. aureus.
Among the 3-aryl hydantoin derivatives described in this
article, compound (3o) in which a 2,6-dichlorophenyl ring
was introduced at the N-3 position of the hydantoin nucleus
showed the highest levels of antibacterial activity (0.044—
0.088 mmol/ml). Compound (3h) that has a 4-dichlorophenyl
ring on the hydantoin ring showed levels of antibacterial
activity (0.048—0.097 mmol/ml) similar to those of the 2,6-
dichloro derivative (3o) and higher than those of other 3-aryl
hydantoin derivatives having a 4-substituted phenyl group
such as F (3l), Br (3m), CH3 (3j), and OCH3 (3k). It is well
known that these 3-aryl hydantoin derivatives form a mixture
of enantimeric or diastereomeric rotational isomers resulting
from restricted internal rotation of the aryl and a heterocyclic
hydantoin system.14) Our results may indicate the complexity
of the contribution of an electronic state of the phenyl ring
and a C–N bond rotational conformer about the C–N pivot
bond connecting the two ring systems for antibacterial activi-
ties. The biological results for both 2,4-dichlorophenyl deriv-
atives (3n) and (3p) apparently indicate not only the impor-
tance of an electronic effect of a substituent on the 3-aryl
group in the hydantoin ring but also conformational
isomerism regarding a C–N bond rotation in 3-aryl
hydantoins.15)
H
H
H
3g
3h
3i
H
4-Cl
4-Cl
4-CH3
4-OCH3
4-F
4-Br
2,4-Cl
2,6-Cl
2,4-Cl
H
3j
3k
3l
3m
3n
3o
3p
3q
3r
3s
S
H
S
H
3tb)
S
H
a) We used Staphylococcus aureus ATCC6538P and E. coli NBRC14237 (NIHJ)
as target organisms. b) Compound 3t dihydrochloride was used for antibacterial ac-
tivity assay.
2-Thiohydantoin analogues (3q—3t) showed no signifi-

August 2010
1125
X
X
R1
R2
R3
4a
4b
S
2a S ––(CH2)2–S–(CH2)2– H
2b ––(CH2)4– 4-C1
O
O
Chart 2
was adjusted exactly to pH 5.4 by addition of 1 M HCl, and an electrolytic
desalting system (Micro Acilyzer®) was used to remove NaCl from the
resulting solution. The obtained product was recrystallized from EtOH. The
yield was 55.8%. The mixture of above compound 2c (0.5 g, 0.00163 mol) in
c-HCl (10 ml) was kept for 1 d at room temperature. Evaporation of the
cant antibacterial activities against either E. coli or S. aureus
strains (Ͼ0.367 mmol/ml).
5-Methylenhydantoin (4a) and 2-thio-5-methylenehydan-
toin (4b) showed lower levels of antibacterial activity than
that of 2,6-dichlorophenyl hydantoin (3o). Ring-opened urea solvent gave the desired compound 3c in 91.5%. The physical spectroscopic
data of compounds 2c and 3c are shown below.
intermediate (2b), which gives a cyclized hydantoin (3h),
also showed the same level of antibacterial activity against E.
3-(4-Methylpiperazin-1-yl)-2-(3-phenylureido)propanoic Acid (2c) mp
143 °C (dec.). IR (KBr) cmϪ1: 3339, 1599. FAB-MS (positive) m/z: 307
coli (gram-negative) (0.051 mmol/ml), but its antibacterial
1
(MϩH)ϩ. H-NMR (D2O) d: 2.82 (3H, s, Ppz-NCH3), 2.84—2.95 (2H, m,
activity against S. aureus (gram-positive) (0.205 mmol/ml)
CH2-Ppz), 3.23 (8H, br, Ppz-H), 4.30—4.33 (1H, m, CHCOOH), 7.15—
7.19 (1H, m, Ar H-4), 7.33—7.41 (4H, m, Ar H-2, H-3, H-5, H-6), 13C-
was lower than that of the cyclized hydantoin (3h). Ring-
NMR (D2O) d: 26.0 (Ppz-NCH3), 36.2, 36.2 (Ppz-C), 36.3 (CHCOOH),
104.2 (Ar C-2, C-6), 107.1 (Ar C-4), 112.4 (Ar C-3, C-5), 121.4 (Ar C-1),
140.6 (NHCONH), 161.1 (COOH). Anal. Calcd for C15H22N4O3·2H2O: C,
52.62; H, 7.65; N, 16.36. Found: C, 52.62; H, 7.46; N, 16.28.
opened urea derivative (2a), which gives a cyclized hydan-
toin (3q), also showed antibacterial activity against E. coli
(gram-negative) (0.098 mmol/ml), but its antibacterial activ-
ity against S. aureus (gram-positive) was also weak (0.394
mmol/ml). The cyclized hydantoin (3q) obtained from com-
pound 2a showed no significant antibacterial activity against
either E. coli or S. aureus strains (Ͼ0.373 mmol/ml). Com-
pound 5 obtained from dimerization of 5-methylenehydan-
toin 4a did not show remarkable antibacterial activity against
either the E. coli or S. aureus strain (Chart 2).
5-{(4-Methylpiperazin-1-yl)methyl}-3-phenylimidazolidine-2,4-dione
Dihydrochloride (3c) mp 192 °C (dec.). IR (KBr) cmϪ1: 1785, 1715.
FAB-MS (positive) m/z: 289 (MϩH)ϩ. 1H-NMR (DMSO-d6) d: 2.78 (3H, s,
Ppz-NCH3), 3.22—3.70 (11H, m, Ppz-H, CH2-Ppz, Hϩ), 4.62 (1H, br, Hyd
H-5), 7.35—7.41 (3H, m, Ar H-3, H-4, H-5), 7.47—7.50 (2H, m, Ar H-2,
H-6), 8.57 [1H, s, Hyd N(1)-H], 11.41 (1H, br, NHϩ). 13C-NMR (DMSO-d6)
d: 41.7 (Ppz-NCH3), 48.9, 49.1, 49.4, 50.8 (Ppz-C), 54.5 (Hyd C-5), 56.9
(Ppz-CH2), 126.6 (Ar C-3, C-5), 127.8 (Ar C-4), 128.6 (Ar C-2, C-6), 132.0
(Ar C-1), 155.5 (Hyd C-2), 171.2 (Hyd C-4). HR-FAB-MS m/z: 289.1666
(Calcd for C15H21N4O2: 289.1665).
On the basis of these results, further molecular modifica-
tions, including isolation of the C–N bond rotational con-
former about the C–N pivot bond, concerning the two ring
3-(4-Bromophenyl)-5-(pyrrolidin-1-ylmethyl)imidazolidine-2,4-dione
Hydrochloride (3m) 4-Bromophenyl isocyanate (1.8 g, 0.0091 mol) was
systems in order to find more active antibacterial compounds added dropwise to a solution of b-pyrrolidinoalanine dihydrochloride9)
(1.5 g, 0.0065 mol) in 3 M-NaOH (10 ml) with vigorous stirring at 50 °C and
stirring was continued for 30 min. The reaction mixture was separated by
filtration in a crystalline material and mother liquid layer. The obtained crys-
talline material was dissolved in c-HCl and insoluble material was filtered
are under investigation. Optical resolution of the compounds
with high levels of activity is also underway.
Experimental
off. The filtrate was warmed at 70 °C for 30 min and then kept at rt to give
Melting points are uncorrected. IR spectra were measured by a Shimadzu crystalline precipitates. The isolated precipitates were washed with water to
FT/IR-8100 spectrometer. The 1H- and 13C-NMR spectra were obtained by a give 4-bromophenylhydantoin (1.03 g, 42.4%). The mother liquid obtained
JEOL JNM A-500 at 35 °C. The chemical shifts were expressed in d ppm
directly from the reaction mixture was concentrated in vacuo, and c-HCl was
downfield from an internal tetramethylsilane (TMS) signal. The signal as- added to the resulting residue. This mixture was warmed at 70 °C for 30 min
signments were confirmed by 1H–1H two-dimensional (2D) correlation spec- and then cooled to give a crystalline precipitate. The collected precipitate
troscopy (COSY), 1H–13C heteronuclear multiple quantum coherence was washed with water also to give 4-bromophenylhydantoin (0.89 g,
(HMQC), and 1H–13C heteronuclear multiple-bond connectivity (HMBC) 36.6%). Total yield was 79.0%. An analytical sample was obtained by re-
spectra. High FAB-MS spectra were obtained by a JEOL JMS-HX110 mass
spectrometer. The abbreviations Ppz, Pyr and Hyd were used for the piper- 1713. FAB-MS (positive) m/z: 338 (MϩH)ϩ. 1H-NMR (DMSO-d6) d:
azine ring, pyrrolidine ring and hydantoin ring, respectively.
1.84—2.07 (4H, m, Pyr H-3, H-4), 2.49—2.50 (2H, m, Pyr HA-2, HA-5),
crystallization from 1 M-HCl, mp 193—196 °C (dec.). IR (KBr) cmϪ1: 1774,
Assays for Antibacterial Activity We used S. aureus ATCC6538P and 3.51—3.63 (4H, m, Pyr HB-2, HB-5, CH2-Pyr), 4.77—4.94 (1H, m, Hyd H-
E. coli NBRC14237 (NIHJ) (gram-positive and gram-negative bacteria, re- 5), 7.35—7.40 (2H, m, Ar H-3, H-5), 7.68—7.72 (2H, m, Ar H-2, H-6), 8.73
spectively) as target organisms. Synthesized compounds (2—5) were dis- [1H, s, Hyd N(1)-H], 10.74 (1H, br s, NHϩ). 13C-NMR (DMSO-d6) d: 22.4,
solved in dimethyl sulfoxide (DMSO) to a concentration of 1.280 mg/ml. 22.6 (Pyr C-3, C-4), 53.7 (Hyd C-5), 54.1, 54.9 (Pyr C-2, C-5), 54.2 (Pyr-
The minimum inhibitory concentration (MIC) of a standard strain was meas-
CH2), 120.7 (Ar C-4), 128.5 (Ar C-3, C-5), 131.1 (Ar C-1), 131.7 (Ar C-2,
ured by the authentic microdilution method to monitor the bacterial growth C-6), 155.0 (Hyd C-2), 169.9 (Hyd C-4). Anal. Calcd for C14H16N3O2Br·
turbidity in Muller–Hinton broth according to the Japanese Society of
Chemotherapy.12,13) The determined values of MIC for target compounds by
this authentic MIC method are summarized in Tables 1 and 2.
HCl: C, 44.88; H, 4.57; N, 11.22. Found: C, 44.60; H, 4.55; N, 11.18.
Other hydantoin derivatives (3k, 3l, 3o) were also obtained in a manner
similar to that described above.
Preparation of 5-{(4-Methylpiperazin-1-yl)methyl}-3-phenylimidazo-
3-(4-Methoxyphenyl)-5-(pyrrolidin-1-ylmethyl)imidazolidine-2,4-
lidine-2,4-dione Hydrochloride (3c) The intermediate urea 2c was pre- dione Hydrochloride (3k) Total yield was 69.7%. mp 181—182 °C
pared from the reaction of 2-amino-2-(4-methylpiperazin-1-yl)propanoic (MeOH). IR (KBr) cmϪ1: 1786, 1718. FAB-MS (positive) m/z: 290 (Mϩ
acid trihydrochloride9) (5 g, 0.0169 mol) and phenyl isocyanate (4 g, 0.0336
H)ϩ. H-NMR (DMSO-d6) d: 1.92—2.04 (4H, m, Pyr H-3, H-4), 3.08 (2H,
1
mol) according to the procedure described previously.10,11) Crude product 2c m, Pyr HA-2, HA-5), 3.62—3.75 (4H, m, Pyr HB-2, HB-5, CH2-Pyr), 3.79

1126
Vol. 58, No. 8
2) Fujisaki F., Oishi M., Sumoto K., Chem. Pharm. Bull., 55, 829—831
(2007).
3) Camille G. W., “The Practice of Medicinal Chemistry,” 3rd ed., Acad-
emic Press, San Diego, 2008.
4) Imberty A., Varrot A., Curr. Opin. Struct. Biol., 18, 567—576 (2008).
5) Ajit V., Richard D. C., Jeffrey D. E. Hudson H. F., Pamela S., Carolyn
R. B., Gerald W. H., Marilynn E. E., “Essentials of Glycobiology,” 2nd
ed., Cold Spring Harbor Laboratory Press, New York, 2009.
6) It has been reported that linezolid uses hydrogen bonding and hy-
drophobic packing interactions to bind to an RNA pocket of the ribo-
somal peptidyltransferase center (PTC).7) Participation of C-5 ac-
etamide NH of the oxazolidinone ring in hydrogen bonding to the
binding site has also been reported.8)
7) Leach K. L., Swaney S. M., Colca J. R., McDonald W. G., Blinn J. R.,
Thomasco L. M., Gadwood R. C., Shinabarger D., Xiong L., Mankin
A. S., Mol. Cell, 26, 393—402 (2007).
8) Ippolito J. A., Kanyo Z. F., Wang D., Franceschi F. J., Moore P. B.,
Steitz T. A., Duffy E. M., J. Med. Chem., 51, 3353—3356 (2008).
9) Abe N., Fujisaki F., Sumoto K., Chem. Pharm. Bull., 46, 142—144
(1998).
10) Fujisaki F., Shoji K., Sumoto K., Heterocycles, 78, 213—220 (2009).
11) Fujisaki F., Shoji K., Sumoto K., Chem. Pharm. Bull., 57, 1415—1420
(2009).
12) The Japanese Society of Chemotherapy (1989), Chemotherapy, 38,
102—105 (1990).
(3H, s, OCH3), 4.80—4.82 (1H, m, Hyd H-5), 7.03 (2H, d, Jϭ8.8 Hz, Ar H-
3, H-5), 7.27 (2H, d, Jϭ8.8 Hz, Ar H-2, H-6), 8.68 [1H, s, Hyd N(1)-H],
11.25 (1H, br s, NHϩ). 13C-NMR (DMSO-d6) d: 22.4, 22.7 (Pyr C-3, C-4),
53.2, 54.0 (Pyr C-2, C-5), 53.7 (Hyd C-5), 55.2 (Pyr-CH2), 114.0 (Ar C-3,
C-5), 124.4 (Ar C-1), 128.0 (Ar C-2, C-6), 155.4 (Hyd C-2), 158.7 (Ar C-4),
170.1 (Hyd C-4). Anal. Calcd for C15H19N3O3·HCl: C, 55.30; H, 6.19; N,
12.90. Found: C, 55.12; H, 6.15; N, 12.89.
3-(4-Fluorophenyl)-5-(pyrrolidin-1-ylmethyl)imidazolidine-2,4-dione
Hydrochloride (3l) Total yield was 77.8%. mp 165—166 °C (MeOH). IR
1
(KBr) cmϪ1: 1776, 1714. FAB-MS (positive) m/z: 278 (MϩH)ϩ. H-NMR
(DMSO-d6) d: 1.93—2.04 (4H, m, Pyr H-3, H-4), 3.09 (2H, br, Pyr HA-2,
HA-5), 3.63—3.70 (4H, m, Pyr HB-2, HB-5, CH2-Pyr), 4.82 (1H, t, Jϭ5.5
Hz, Hyd H-5), 7.33—7.35 (2H, m, Ar H-3, H-5), 7.42—7.45 (2H, m, Ar H-
2, H-6), 8.75 [1H, s, Hyd N(1)-H], 11.20 (1H, br s, NHϩ). 13C-NMR
(DMSO-d6) d: 22.5, 22.7 (Pyr C-3, C-4), 53.7 (Hyd C-5), 53.3, 54.1 (Pyr C-
2, C-5), 55.1 (Pyr-CH2), 115.5 (d, Jϭ23 Hz, Ar C-3, C-5), 128.0 (Ar C-1),
128.8 (d, Jϭ9.0 Hz, Ar C-2, C-6), 155.1 (Hyd C-2), 161.1 (d, Jϭ245 Hz, Ar
C-4), 169.9 (Hyd C-4). Anal. Calcd for C14H16N3O2F·HCl: C, 53.59; H,
5.46; N, 13.39. Found: C, 53.51; H, 5.50; N, 13.40.
3-(2,6-Dichlorophenyl)-5-(pyrrolidin-1-ylmethyl)imidazolidine-2,4-
dione Hydrochloride (3o) Total yield was 73.7%. mp Ͼ225 °C (dec.). IR
1
(KBr) cmϪ1: 1802, 1735. FAB-MS (positive) m/z: 328 (MϩH)ϩ. H-NMR
(DMSO-d6) d: 1.92—2.06 (4H, m, Pyr H-3, H-4), 3.12 (2H, br s, Pyr HA-2,
HA-5), 3.61—3.73 (4H, m, Pyr HB-2, HB-5, CH2-Pyr), 5.18 (1H, d, Jϭ9.0
Hz, Hyd H-5), 7.60 (1H, t, Jϭ8.2 Hz, Ar H-4), 7.70—7.72 (2H, m, Ar H-3,
H-5), 9.14 [1H, s, Hyd N(1)-H], 11.20 (1H, br s, NHϩ). 13C-NMR (DMSO-
d6) d: 22.4, 22.6 (Pyr C-3, C-4), 53.0, 54.1 (Pyr C-2, C-5), 54.3 (Hyd C-5),
55.3 (Pyr-CH2), 127.0 (Ar C-1), 128.3, 128.9 (Ar C-3, C-5), 132.4 (Ar C-4),
134.1, 134.3 (Ar C-2, C-6), 152.9 (Hyd C-2), 168.8 (Hyd C-4). Anal. Calcd
for C14H15N3O2Cl2·HCl: C, 46.11; H, 4.42; N, 11.52. Found: C, 45.86; H,
4.32; N, 11.39.
13) The Japanese Society of Chemotherapy (1992), Chemotherapy, 41,
184—189 (1993).
14) Colebrook L. D., Can. J. Chem., 69, 1957—1963 (1991).
15) In the 13C-NMR spectroscopic analysis of the compounds (3n, 3o, 3p),
compound 3o showed a singlet resonance pattern ascribable to all 2,6-
dichlorophenyl ring and hydantoin nucleus carbons; however, 2,4-
dichlorophenyl compounds (3n, 3p) showed a doublet resonance pat-
tern for all carbons as a mixture of two rotational conformers as noted
in a previous paper (see ref. 11 for spectroscopic data of 3n, 3p).
References and Notes
1) Fujisaki F., Abe N., Sumoto K., Chem. Pharm. Bull., 52, 1238—1241
(2004).