Preparation and antiviral activity of some new C3- and CS-symmetrical tri-substituted triazine derivatives having benzylamine substituents

Article abstract of DOI:10.1248/cpb.c18-00274

We report the preparation of new C₃- and C_S-symmetrical molecules constructed on a triazine (TAZ) template. Anti-herpes simplex virus type 1 (anti-HSV-1) and cytotoxic activities against Vero cells of synthesized TAZ derivatives were evaluated. The results suggested that the presence of an electron-donating group(s) on the benzene ring in benzylamine groups on the TAZ template is an important structural factor for expressing a high level of anti-HSV-1 activity and low cytotoxicity for these C₃ types of TAZ derivatives. Among the tested TAZ derivatives, compounds 4f and 7h showed the highest anti HSV-1 activities (EC₅₀=0.98 and 1.23μM, respectively) and low cytotoxic activities to Vero cells (50% cytotoxic concentration (CC₅₀)=292.2 and >200μM, respectively).

Full text of DOI:10.1248/cpb.c18-00274

830
Chem. Pharm. Bull. 66, 830–838 (2018)
Vol. 66, No. 8
Note
Preparation and Antiviral Activity of Some New C3- and
CS-Symmetrical Tri-Substituted Triazine Derivatives Having
Benzylamine Substituents
Nobuko Mibu,a Kazumi Yokomizo,b Marina Sano,a Yuuna Kawaguchi,a Kenta Morimoto,a
Syunsuke Shimomura,a Ryo Sato,a Nozomi Hiraga,b Aya Matsunaga,b Jian-Rong Zhou,b
,a
Tomonori Ohata,a Hatsumi Aki,a and Kunihiro Sumoto*
a Faculty of Pharmaceutical Sciences, Fukuoka University; 8–19–1 Nanakuma, Jonan-ku, Fukuoka 814–0180,
b
Japan: and Faculty of Pharmaceutical Sciences, Sojo University; 4–22–1 Ikeda, Nishi-ku, Kumamoto 860–0082,
Japan.
Received April 10, 2018; accepted June 4, 2018
We report the preparation of new C3- and CS-symmetrical molecules constructed on a triazine (TAZ)
template. Anti-herpes simplex virus type 1 (anti-HSV-1) and cytotoxic activities against Vero cells of syn-
thesized TAZ derivatives were evaluated. The results suggested that the presence of an electron-donating
group(s) on the benzene ring in benzylamine groups on the TAZ template is an important structural fac-
tor for expressing a high level of anti-HSV-1 activity and low cytotoxicity for these C3 types of TAZ de-
rivatives. Among the tested TAZ derivatives, compounds 4f and 7h showed the highest anti HSV-1 activities
(EC50=0.98 and 1.23µM, respectively) and low cytotoxic activities to Vero cells (50% cytotoxic concentration
(CC50)=292.2 and >200µM, respectively).
Key words 1,3,5-triazine; benzylamine-substituent; C3-symmetry; anti-herpes simplex virus type 1; hydro-
gen bond donor; structure–activity relationship
In the search for new types of antiviral active compounds, some TAZ derivatives that have benzylamine substituents on
extensive efforts have been made to find promising new anti- a TAZ template such as compound 4h show a high level of
viral candidates.1) It is well known that many types of recep- anti-HSV-1 activity (EC50=5.4 µM) and low cytotoxicity (50%
tors or functionalized proteins on membranes in a native state cytotoxic concentration (CC50)=291.9 µM). In terms of a struc-
often have a high order of symmetrical interfaces.2) C3- or C2- ture–activity relationship (SAR) study and finding new types
geometric symmetrical molecules have frequently been found of antiviral active leads, molecular modification by the intro-
in various synthetic biologically active compounds.3) Aiming duction of benzylamine functionalities into a TAZ template
to develop new synthetic bioactive compounds, we targeted seems to be interesting.
such geometrical symmetric molecules constructed on a sym-
metrical template.
Here, we describe the synthesis of new types of symmetri-
cal TAZ derivatives that have various benzylamine substitu-
In our previous studies on antiviral compounds in the tri- ents on symmetrical TAZ templates and the results of their
substituted 1,3,5-triazine (TAZ) series, we found that many biological evaluations.
of the new C3- and CS-symmetrical TAZ derivatives synthe-
sized previously showed a wide range of bioactivities against
herpes simplex virus type 1 (HSV-1) or cytotoxicic activities
Results
Synthesis of New Target Derivatives of Symmetrical Tri-
to Vero cells.4) Regarding tri-substituted TAZ derivatives, Substituted TAZ Derivatives Our strategies for the synthe-
we have reported that some symmetrical TAZ derivatives sis of target TAZ derivatives by using 2,4,6-trichlorotriazine
having alkoxy and/or alkylamino substituents show a high (TCTAZ: 1) as a starting material are summarized in Chart 1.
level of anti-HSV-1 activity5) (Fig. 1). Notably, we found that
The pathway for the synthesis of C3- and CS-type symmetri-
cal TAZ derivatives (4 and 7) together with intermediates of
TAZ derivatives is shown in Chart 1. All of the substitution
reactions of the starting TCTAZ (1) or monoalkoxy-dichloro-
TAZ (5)5) with various benzylamines (2a–k) were performed
in a one-pot reaction and the desired new TAZ derivatives (4
and 7) were obtained. All of the target C3-type TAZ deriva-
tives (4) were obtained in moderate to good yields (42–85%)
as shown in Table 1, and CS-type symmetrical TAZ deriva-
tives (7) were also obtained in moderate yields (Table 2). For
the synthesis of these new targeted C3- and CS-symmetrical
tri-substituted TAZ derivatives, we used the same procedure
as that described for the preparation of symmetrical TAZ de-
rivatives (see Experimental).
Fig. 1. Symmetrical Target Molecules Constructed on Tri-Substituted
TAZ Derivatives
All of the structures of the synthesized C3- and CS-sym-
*To whom correspondence should be addressed. e-mail: kunihiro@adm.fukuoka-u.ac.jp
© 2018 The Pharmaceutical Society of Japan

Vol. 66, No. 8 (2018)
Chem. Pharm. Bull.
831
Chart 1. Synthesis of C3- and CS-Symmetrical TAZ Derivatives
Table 1. Synthesis of C3-Symmetrical Benzylamine-Type TAZ Deriva-
tives (4)
a high level of anti-HSV-1 activity (EC50=0.98µM) and a low
level of cytotoxic activity (CC50=292.2µM) as did compound
4h5) (EC50=5.4 µM and CC50=291.9 µM) reported previously.
All of the compounds that have electron-withdrawing sub-
stituents (4c and 4d) including non-substituted compound
4a showed considerably high levels of anti-HSV-1 activity
(EC50=7.4–13.2 µM) and cytotoxic activity (CC50=5.5–94.9µM).
Regarding the two biological activities (anti-HSV-1 activity
and cytotoxic activity), the opposite order in electron-with-
drawing (attracting) effects between the two activities was
observed (4a<4c<4d for anti-HSV-1 activity and 4a>4c>4d
for cytotoxic activity). Lower levels of cytotoxic activity
(CC50=13.0–94.9 µM) were observed for compounds 4c and 4d
than for non-substituted compound 4a.
Reaction time of MW
Entry
ArCH2NH2 (2)
Products (yield %)
(min)a)
1
2
3
4
5
6
7
8
9
2a
2b
2b
2c
2d
2e
2f
60
60
40b)
60
60
30
50
20
20
4a (85)
4b (53)
3b (46)c), 4b (5)c)
4c (75)
4d (42)
4e (66)
4f (80)
2g
2i
4g (57)
4i (63)
a) In the all reactions except for Entry 3, stirring of the reaction mixtures (ratio
of 1:2=1:10) in dioxane were conducted at 0°C for 30min, at room temperature
for 1h, and then irradiation of microwave (100W, 100°C) for a proper shown time.
b) Stirring the reaction mixture (ratio of 1:2b=1:6) in THF was conducted at room
temperature for 10min, and then irradiation of microwave (90W, 70°C) for 20min. c)
Yields after recrystallization.
Considerably high levels of anti-HSV-1 activity
(EC50=0.98–38.7 µM) were observed for C3-type compounds
(4b, 4f, 4h5) and 4i) that have electron-donating substituents
such as methyl or methoxy groups on the benzene rings ex-
cept for compounds 4g and 4e (see Table 3), and these com-
metrical TAZ derivatives (4 and 7) and a few intermediates pounds showed cytotoxic activities over 200µM. The obtained
(3, 6) were confirmed by spectroscopic and analytical data. biological results indicated that the nature of substituents on
The geometries of the obtained symmetrical TAZ derivatives the benzene rings prefers electron-donating substituents for
described above were confirmed from 13C-NMR spectroscopic expressing a high level of anti-HSV-1 activity and low level
data6) (see Experimental for details).
of cytotoxicity for these C3 types of TAZ derivatives. We also
Biological Activity and Discussion In many synthetic consider that benzylamine groups in C3-type molecules may
receptor-type molecules mimicking the supramolecular inter- act as hydrogen-bond donors to receptor binding sites.
action of biomolecules, it is expected that the ability to form
The exceptional anti-HSV-1 activity for compound 4g may
multiple hydrogen bonds plays an important role in guest mol- be due to intramolecular hydrogen bond formation between
ecule recognition. Considering the hydrogen bonded interac- the basic benzylamine moiety and the ortho-methoxy group in
tion in a supramolecular host-guest system, it is also expected the molecule 4g that weakens such intermolecular hydrogen-
that a convergent orientation of incorporated functional groups bonding interaction of the TAZ molecule 4g to receptor bind-
is an effective array to produce multiple hydrogen bonding ing sites (see Fig. 2). This exceptional result for compound 4g
interactions between host and guest molecules.7,8) From this also indicates the importance of intermolecular hydrogen bond
point of view, title C3- and CS-geometrical molecules that formation ability of C3-type TAZ molecules in the supramo-
have donors or acceptors for hydrogen bonds on a symmetri- lecular interaction with its binding site for expressing a high
cal TAZ template are thought to offer new biologically active level of anti-HSV-1 activity.
molecules.
Despite the considerably high level of cyctotoxic activity
From biological evaluations of anti-HSV-1 activities (EC50) (CC50=22.6µM) of compound 4e, the reason for exception-
by plaque reduction assays9) and cytotoxic activities (CC50) ally low level of anti-HSV-1 activity (EC50>100 µM) for this
against Vero cells of synthesized TAZ derivatives (Table 3), compound is still unclear at present. The positional effect of
most of the C3-symmetrical benzylamine-type TAZ deriva- methoxy groups on benzene rings in these TAZ derivatives
tives (4) presented hydrogen bond donor protons of a benzyl- may be required for expression of anti-HSV-1 activity.
amine (–NH–) functionality. Many of the C3-symmetrical
Among the CS-symmetrical benzylamine-type TAZ de-
benzylamine-type TAZ derivatives (4) showed a significantly rivatives (7a, 7b, 7e–k) as shown in Table 3, a CS-symmetrical
high level of anti-HSV-1 activity, and compound 4f showed benzylamine-type TAZ derivative (7h) that has two benzyl-

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Chem. Pharm. Bull.
Vol. 66, No. 8 (2018)
Table 2. Synthesis of CS-Symmetrical Benzylamine-Type TAZ Derivatives (7)
Entry
ArCH2NH2 (2)
Ratio of 1:2 (:DIPEA)a)
Reaction conditionsa)
Product (yield %)
1
2
2a
2a
2b
2e
2f
1:1:1 (DIPEA)
0°C 2h
6a (97)
7a (79)
7b (82)b)
7e (75)b)
7f (75)b)
7g (72)
7h (34)b)
7i (89)
1:5
1:5
1:5
1:6
1:5
1:3
1:5
1:5
1:5
MW 60min
MW 45min
MW 60min
MW 30min
MW 30min
MW 30min
MW 30min
MW 30min
MW 45min
3
4
5
6
2g
2h
2i
7
8
9
2j
7j (84)b)
10
2k
7k (78)
a) In the all reactions except for Entry 1, the reaction mixtures were subjected to microwave irradiation (100W, 100°C) in dioxane. In the reaction of Entry 1, the reaction
mixture with N,N-diisopropylethylamine (DIPEA) was used in THF. b) Yields after recrystallization.
Table 3. Anti-HSV-1 Activity (EC50) and Cytotoxicity (CC50) against Vero Cells of Synthesized New C3- and CS-Symmet-
rical Benzylmine-Type TAZ Derivatives (4, 7) and Intermediates (3, 6)
a) Data were taken from ref. 5). b) Data were taken from ref. 15).

Vol. 66, No. 8 (2018)
Chem. Pharm. Bull.
833
eter. MicromATR Vision [an apparatus of attenuated total
reflectance (ATR)] was used for a neat sample operation.
Low- and high-resolution mass spectra (LR-MS and HR-MS)
were obtained by a JEOL JMS HX-110 double-focusing model
equipped with an FAB ion source interfaced with a JEOL
l
JMA-DA 7000 data system. H- and 13C-NMR spectra were
obtained by ECG600R. Chemical shifts were expressed in δ
ppm downfield from an internal tetramethylsilane (TMS) sig-
1
nal for H-NMR and the carbon signal of the corresponding
solvent [CDCl3 (77.00ppm), dimethyl sulfoxide (DMSO)-d6
Fig. 2. Intramolecular Hydrogen Bond Formation in Compound 4g
(39.50ppm), THF-d8 (67.20ppm)] for 13C-NMR. The signal
amine groups with electron-donating substituents and an isop- assignments were confirmed by two-dimensional (2D)-NMR
1
1
ropoxy group showed a considerably high level of anti-HSV-1 analyses: H–1H 2D correlation spectroscopy (COSY), H–13C
activity (EC50=1.23 µM); however, many structurally related heteronuclear multiple-quantum coherence (HMQC), and
CS-symmetrical derivatives (7a, 7b, 7e, 7f, 7g and 7k) showed 1H–13C heteronuclear multiple-bond connectivity (HMBC).
low levels of anti-HSV-1 activity (EC50=>100 µM) compared Microanalyses were performed with a Yanaco MT-6 CHN
to that of compound 7h. Compounds 7i and 7j showed moder- corder. Routine monitoring of reactions was carried out using
ate levels of anti-HSV-1 activity (EC50=72.1 and 12.6µM, re- precoated Kieselgel 60F254 plates (E. Merck). Microwave ir-
spectively). Interestingly, many compounds in this series (7a, radiation experiments were carried out in a CEM Discover
7b, 7g, 7i, 7j and 7k) showed moderate levels of cytotoxic ac- Focused Microwave System. For the separation of crude prod-
tivity (CC50=14.6–192.4µM, see Table 3). Intermediates 3 and ucts in small experimental scales (below 2 mmol), we applied
6 listed in Table 3 showed almost no anti-HSV-1 or cytotoxic Centrifugal chromatography separation of the reaction products
activity (see Table 3).
on silica gel (Kanto 60N or Able-Biott) with a UV detector.
Regarding calculated logP values10) for the compounds (see Commercially available starting materials were used without
Supplementary Materials), there were few distinct correlations further purification, and dry solvents were used in all reactions.
between logP values and anti-HSV-1 activity (EC50) values
General Procedure for the Preparation of C3-Symmet-
shown in Table 3.
rical Benzylamine-Type TAZ Derivatives (4) (Table 1):
The results showing high levels of anti-HSV-1 activity for Example: Synthesis of N2,N4,N6-Tribenzyl-1,3,5-triazine-
C3- or CS-symmetrical compounds (4f and 7h) strongly sug- 2,4,6-triamine (4a) (Entry 1) To a solution of TCTAZ (1,
gest that at least the presence of two hydrogen bond donor 277mg, 1.50mmol) in dioxane (2.5mL), a solution of benzyl-
benzylamine protons in the target TAZ derivatives is required amine (2a, 1.61g, 15.0mmol) in dioxane (1.5mL) was added
as an important structural factor for the expression of a high dropwise at 0°C, and the mixture was continuously stirred for
level of anti-HSV-1 activity. A similar assumption is also sub- 30min at room temperature and then for another 1h at room
stantiated by our previous observation of the disappearance of temperature. Then the mixture was subjected to microwave
anti-HSV-1 activity by N-acetylated C3-symmetrical amine- irradiation (MW) at 100°C (100W) for 60min with stirring.
type molecules.11)
After addition of water (30mL), the mixture was extracted
In the comparison with the anti-HSV-1 activity of acyclovir, with EtOAc (2×25mL). The combined organic layer was dried
it was found that the mode of action of acyclovir is different over MgSO4. After evaporation of the solvent, the residual
from the modes of action of TAZ derivatives described in this solid was purified by centrifugal chromatography (n-hexane–
paper; however, it is noteworthy that some new symmetrical EtOAc=50:50) to give an analytically pure 4a (507mg,
TAZ derivatives such as 4f and 7h showed similar levels of 1.28mmol, 85%) as a pale yellow solid.
anti-HSV-1 activity with a large safety index value.
4a: mp 103.0–104.5°C (from 2-PrOH). IR cm−1: 3405, 3249
The results of calorimetric experiments12) showed sugar (NH), 1536, 1500 (C=N), 1163 (C–N). H-NMR (CDCl3) δ:
recognition properties of highly active compounds with good 4.53 (6H, brs, CH2), 5.39 (3H, brs, NH), 7.18–7.32 (15H, m,
SI values (CC50/EC50) such as compound 4f (SI=298). From H, C2′, 3′, 4′, 5′, 6′), 13C-NMR (CDCl3) δ: 44.56 (ArCH2),
the point of the view of substituents as hydrogen-bond donors 127.02 (C4′), 127.51 (C2′, 6′), 128.44 (C3′, 5′), 139.45 (C1′),
or acceptors, ITC experiments suggested that the reaction of 166.27 (C2, 4, 6). Positive-ion FAB-MS m/z: 397 (M+H+).
compound 4f with sugars showed a thermodynamic signature HR-FAB-MS m/z: 397.2147 (Calcd for C24H25N6: 397.2147).
different from that of the entropically driven reaction of tri- Anal. Calcd for C24H24N6: C, 72.70; H, 6.10; N, 21.20. Found:
isopropoxy-substituted TAZ derivative. Thus, we consider that C, 72.70; H, 6.19; N, 21.05.
1
such an enthalpic C3-type TAZ derivative having benzylamine
N2,N4,N6-Tris(4-methylbenzyl)-1,3,5-triazine-2,4,6-tri-
functionalities may act as a hydrogen-bond donor to proposed amine (4b) (Entry 2) Compound 4b was prepared from
receptor binding sites. On the basis of the obtained structural the reaction of 1 with 4-methylbenzylamine (2b) under the
information on biological activities in this series, we are fur- conditions shown in Table 1. Purification by centrifugal chro-
ther investigating chemical modifications to new TAZ frame- matography (CH2Cl2–EtOH=97:3) afforded 4b (53%) as a
work molecules in order to find new promising leads.
white solid. An analytical sample of 4b was obtained as white
crystals by concentration of the filtrate.
4b: mp 116–117°C (from 2-PrOH). IR cm−1: 3440 (NH),
Experimental
Melting points were determined using a micro melting point 1575, 1504 (C=N), 1346, 1245 (C–N), 808 (1,4-disubstituted
apparatus (Yanaco MP-S3) without correction. IR spectra benzene). 1H-NMR (CDCl3) δ: 1.83 (1.6H, brs, NH), 2.31
were measured by a JASCO FTIR-4100 IR spectrophotom- (9H, s, CH3), 4.50 (6H, brs, Hα), 5.17 (0.6H, brs, NH), 5.27

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Chem. Pharm. Bull.
Vol. 66, No. 8 (2018)
(0.8H, brs, NH), 7.08 (6H, d, J=7.3Hz, H3′, 5′), 7.16 (6H, d,
4d: mp 128–130°C (from 2-PrOH). IR cm−1: 3462, (NH),
J=7.3Hz, H2′, 6′). 13C-NMR (CDCl3) δ: 21.06 (CH3), 44.40 1530, 1502 (C=N), 1323, 1105, 1066 (C–N and/ or C–O).
(Cα), 127.54 (C2′, 6′), 129.13 (C3′, 5′), 136.40 (C1′), 136.62 1H-NMR (DMSO-d6) δ: 4.39, 4.42*, 4.51, 4.52 (6H, brs, Cα),
(C4′), 166.28 (C2, 4, 6). Positive-ion FAB-MS m/z: 439 7.19*, 7.42 (3H, brs, NH), 7.31, 7.48* (6H, brs, C2′, 6′), 7.49,
(M+H)+. HR-FAB-MS m/z: 439.2603 (Calcd for C27H31N6: 7.66* (6H, d, J=8.2Hz, C3′, 5′). 13C-NMR (DMSO-d6) δ:
439.2610). Anal. Calcd for C27H30N6: C, 73.94; H, 6.89; N, 42.74, 42.97* (Cα), 124.27* (q, J=273.1Hz, CF3) 124.39 (q,
19.16. Found: C, 73.91; H, 6.98; N, 19.07.
J=271.7Hz, CF3), 124.74*, 124.96 (C3′, 5′), 127.02*, 127.11 (q,
6-Chloro-N2,N4-bis(4-methylbenzyl)-1,3,5-triazine-2,4- J=31.8Hz, C4′), 127.55, 127.67* (C2′, C6′), 145.66, 145.77*
diamine (3b) (Entry 3) Compound 3b was obtained from (C1′), 165.80, 166.00* (C2, 4, 6). (The observed signals of the
the reaction of 1 and 2b in THF (ratio of 1:2b=1:6) under predominant tautomer are asterisked.) Positive-ion FAB-MS
the conditions shown in Table 1 in 46% yield after recrystal- m/z: 601 (M+H)+. HR-FAB-MS m/z: 601.1763 (Calcd for
lization from 2-PrOH as a white solid together with 4b (5%) C27H22F9N6: 601.1762). Anal. Calcd for C27H21F9N6·0.7H2O: C,
obtained by concentration of the filtrate.
52.89; H, 3.68; N, 13.71. Found: C, 53.06; H, 3.38; N, 13.69.
3b: mp 235–237°C (from 2-PrOH). IR cm−1: 3248 (NH),
N2,N4,N6-Tris(4-methoxybenzyl)-1,3,5-triazine-2,4,6-tri-
1541, 1511 (C=N), 1343, 1091 (C–N and/or C–O), 796, 582 (C– amine (4e) (Entry 6) Compound 4e was prepared from the
1
Cl). H-NMR (THF-d8) δ: 2.27, 2.28* (6H, s, CH3), 4.44–4.49 reaction of 1 with 4-methoxybenzylamine (2e) under the con-
(4H, m, CH2), 4.71 (0.4H, brs, NH), 7.01–7.09 (4H, m, H3′, 5′), ditions shown in Table 1. Separation of the products by cen-
7.11–7.19 (4H, m, H2′, 6′), 7.29 (0.8H, brs, NH), 7.40 (0.8H, brs, trifugal chromatography (CH2Cl2–EtOH=97:3) gave 4e (66%)
NH). 13C-NMR (THF-d8, 67.20) δ: 20.93 (CH3), 44.58, 44.75, as a white solid. An analytical sample of 4e was obtained as a
44.80* (CH2), 127.85, 128.14*, 128.27 (C2′, C6′) 129.47 (C3′, white solid by recrystallization from EtOH.
5′), 136.84*, 136.90, 136.98, 137.02 (C4′), 137.13, 137.16* (C1′),
4e: mp 135–136°C (from EtOH). IR cm−1: 3439, 3367 (NH),
166.93, 167.08*, 167.24 (C2, 4), 169.58*, 170.10* (C6). (The 1556, 1499 (C=N), 1345, 1246, 1171, 1030 (C–N or C–O),
1
observed 1H- and 13C-signals assignable to the predominant 810 (1,4-disubstituted benzene). H-NMR (DMSO-d6) δ: 3.70
tautomer are asterisked.) Positive-ion FAB-MS m/z: 354 (9H, s, OCH3), 4.33 (6H, brs, Hα), 6.77 (3H, brs, H3′, 5′ of
(M+H)+. HR-FAB-MS m/z: 354.1482 (Calcd for C19H21ClN5: B), 6.81–6.87† (1H, NH), 6.83 (3H, d, J=6.9Hz, H3′, 5′ of A),
354.1485). Anal. Calcd for C19H20ClN5: C, 64.49; H, 5.70; N, 7.01 (1.6H, brs, NH), 7.13 (3H, brs, H2′, 6′ of B), 7.18 (3H, d,
19.79. Found: C, 64.47; H, 5.76; N, 19.72.
J=6.9Hz, H2′, 6′ of A), 7.16–7.23† (0.4H, NH). (The peaks
N2,N4,N6-Tris(4-chlorobenzyl)-1,3,5-triazine-2,4,6-tri- with the mark† attached are assumed to be overlapped with
amine (4c) [112484-31-8] (Entry 4) Compound 4c was the peaks of NH.) 13C-NMR (DMSO-d6) δ: 42.40, 42.67* (Cα)
prepared from the reaction of 1 with 4-chlorobenzylamine (2c) 54.93 (OCH3), 113.37 (C3′, 5′), 128.21 (C2′, 6′ of A), 128.51*
under the conditions shown in Table 1. Separation of the prod- (C2′, 6′ of B), 132.80*, 132.90 (C1′), 157.86 (C4′), 165.74*,
ucts by centrifugal chromatography (CH2Cl2–EtOH=97:3) 165.86 (C2, 4, 6). (Signals for only the predominant tautomer
gave 4c (75%) as a white solid. An analytical sample of 4c B are asterisked.) Positive-ion FAB-MS m/z: 487 (M+H)+.
was obtained as colorless crystals by recrystallization from HR-FAB-MS m/z: 487.2460 (Calcd for C27H31N6O3: 487.2458).
propionitrile (EtCN).
Anal. Calcd for C27H30N6O3: C, 66.65; H, 6.21; N, 17.27.
4c: mp 156–158°C (from EtCN). IR cm−1: 3396, 3246 (NH), Found: C, 66.47; H, 6.15; N, 17.19.
1
1526 (C=N), 1330, 1161 (C–N). H-NMR (DMSO-d6) δ: 4.31
N2,N4,N6-Tris(3,4-dimethoxybenzyl)-1,3,5-triazine-
(3.3H, brs, Hα of tautomer B), 4.40 (2.7H, d, J=5.5Hz, Hα 2,4,6-triamine (4f) (Entry 7) Compound 4f was prepared
of tautomer A), 7.05 (0.6H, brs, NH of A), 7.15 (3.3H, brs, from the reaction of 1 with 3,4-dimethoxybenzylamine (2f)
H2′, 6′ of B), 7.19 (1.2H, brs, NH of A and B), 7.23 (3.3H, under the conditions shown in Table 1. Separation of the prod-
brs, H3′, 5′ of B), 7.28 (2.7H, d, J=7.6Hz, H2′, 6′ of A), ucts by centrifugal chromatography (CH2Cl2–EtOH=95:5)
ca. 7.32 (1.2H, brs, NH of B), 7.34 (2.7H, d, J=7.6Hz, H3′, gave 4f (80%) as a white solid. An analytical sample of 4f was
5′ of A). (The integral values of the peaks at δH 7.15–7.34 obtained as a colorless solid by recrystallization from 2-PrOH.
were calculated from the spectral data after addition of D2O.) Compound 4f was converted into hydrochloride (4f·HCl) as
13C-NMR (DMSO-d6) δ: 42.37 (Cα of A), 42.66 (Cα of B), colorless crystals by a routine procedure.
127.88 (C3′, C5′ of B), 127.98 (C3′, C5′ of A), 128.80 (C2′, 6′
4f: mp 47°C (from 2-PrOH). IR cm−1: 3378 (NH), 1501
1
of A), 128.96 (C2′, 6′ of B), 130.82 (C4′ of A and B), 139.86 (C=N), 1257, 1230, 1134, 1023 (C–N and/or C–O). H-NMR
(C1′ of A and B), 165.72 (C2, 4, 6 of A), 165.89 (C2, 4, 6 of (CDCl3) δ: 1.80 (1.8H, brs, NH), 3.85 (9H, s, OCH3 on C3′),
B). Positive-ion FAB-MS m/z: 499 (M+H+). HR-FAB-MS m/z: 3.87 (9H, s, OCH3 on C4′), 4.53 (6H, brs, ArCH2), 5.19 (0.5H,
499.0975 (Calcd for C24H22Cl3N6: 499.0972). Anal. Calcd for brs, NH), 5.33 (0.7H, brs, NH), 6.80 (3H, d, J=7.6Hz, H5′),
C24H21Cl3N6: C, 57.67; H, 4.23; N, 16.81. Found: C, 57.63; H, 6.85 (3H, d, J=7.6Hz, H6′), 6.86 (3H, s, H2′). 13C-NMR
3.97; N, 16.81.
(CDCl3) δ: 44.54 (ArCH2), 55.82, 55.90 (OCH3), 110.90
N2,N4,N6-Tris[4-(trifluoromethyl)benzyl]-1,3,5-triazine- (C2′), 111.09 (C5′), 119.77 (C6′), 131.86 (C1′), 148.20 (C4′),
1
2,4,6-triamine (4d) (Entry 5) Compound 4d was prepared 149.01 (C3′), 166.17 (C2, 4, 6). H-NMR (DMSO-d6) δ: 3.65,
from the reaction of 1 with 4-(trifluoromethyl)benzylamine 3.70* (18H, brs, OCH3 on C3′, 4′), ca. 3.7 (1H, brs, NH),
(2d) under the conditions shown in Table 1. Separation of 4.34, 4.35* (6H, brs, ArCH2), 6.72–6.97 (9H, m, ArH), [7.02
the products by centrifugal chromatography (n-hexane– (1.6H), 7.17 (0.4H)] (brs, NH). 13C-NMR (DMSO-d6) δ: 42.87,
EtOAc=30:70) gave 4d (42%) as a white solid. An analytical 43.13* (ArCH2), 55.35, 55.49 (OCH3 on C3′, 4′), 111.50 (C2′,
sample of 4d was obtained as a white solid by recrystalliza- 5′), 119.11, 119.49* (C6′), 133.29 (C1′), 147.48, 148.48 (C3′,
tion from 2-PrOH.
4′), 165.81 (C2, 4, 6). (The observed 1H- and 13C-signals
assignable to the predominant tautomer are asterisked.)

Vol. 66, No. 8 (2018)
Chem. Pharm. Bull.
835
Positive-ion FAB-MS m/z: 577 (M+H)+. HR-FAB-MS m/z: C33H42N6O9·0.5 2-PrOH·0.5H2O: C, 58.71; H, 6.71; N, 11.91.
577.2784 (Calcd for C30H37N6O6: 577.2775). Anal. Calcd for Found: C, 58.57; H, 6.74; N, 11.78.
C30H36N6O6·i-PrOH: C, 62.25; H, 6.97; N, 13.26. Found: C,
62.35; H, 6.89; N, 13.22.
Preparation of Intermediate Di-benzylamino-Substituted
TAZ Derivatives (3)
4f·HCl: mp 128–131°C (from 2-PrOH–H2O). IR cm−1:
6-Chloro-N2, N4 -bis(3,4-dimethoxylbenzyl)-1,3,5-
3254 (br, NH+), 1625 (NH2+), 1567, 1515 (C=N), 1263, 1234, triazine-2,4-diamine (3f)
1
1137, 1023 (C–N and/or C–O). H-NMR (DMSO-d6) δ: 3.69*,
This compound was prepared in a manner similar to that
3.73*, 3.75 (18H, brs, OCH3 on C3′, 4′), ca. 3.7 (1H, brs, NH), for the preparation of 3h described by Vidal-Mosquera et al.13)
4.46*, 4.48 (6H, brs, ArCH2), 6.75–7.15 (9H, m, ArH), 8.82*, To a solution of 1 (922mg, 5.0mmol) in THF (100mL), 2f
8.88, 9.03 (3H, brs, NH). 13C-NMR (DMSO-d6) δ: 43.23*, (3.34g, 20.0mmol) was added dropwise at room temperature,
43.45, 43.76 (ArCH2), 55.39, 55.48*, 55.52*, 55.54 (OCH3), and then the mixture was refluxed for 1.2h. Then the white
111.60*, 111.71*, 111.83 (C2′, 5′), 119.81 (C6′), 130.10*, solids were filtered, and water (200mL) was added. After the
130.48, 131.03 (C1′), 147.96, 148.03, 148.13*, 148.64* (C3′, 4′), mixture had been stirred at 60°C for 10min, the solid was fil-
1
154.54*, 162.64 (C2, 4, 6). (The observed H- and 13C-signals tered and washed with EtOH (50mL) to give analytically pure
assignable to the predominant tautomer are asterisked.) compound 3f (1.51g, 4.29mmol, 86%) as a white solid.
Positive-ion FAB-MS m/z: 577 (M+H)+. HR-FAB-MS m/z:
577.2766 (Calcd for C30H37N6O6: 577.2775). Anal. Calcd for 1240, 1137, 1021 (C–N and/or C–O), 799, 736 (C–Cl). H-NMR
C30H36N6O6·HCl·1.6H2O : C, 56.13; H, 6.31; N, 13.09. Found: (DMSO-d6) δ: 3.67* (3.3H, s, OCH3 on C3′), 3.71* (3.3H, s,
C, 56.13; H, 6.26; N, 13.05.
3f: mp 193–194. IR cm−1: 3250 (NH), 1555, 1514 (C=N),
1
OCH3 on C4′), 3.72 (3.6H, brs, OCH3), 3.73 (1.8H, s, OCH3),
N2,N4,N6-Tris(2,4-dimethoxybenzyl)-1,3,5-triazine- 4.33–4.40 [4H, m, Cα: including 4.38* (d, J=6.2Hz)], 6.72–6.96
2,4,6-triamine (4g) (Entry 8) Compound 4g was prepared [6H, m, ArH: including 6.73* (1.1H, dd, J=8.3, 1.4Hz, H6′),
from the reaction of 1 with 2,4-dimethoxybenzylamine (2g) 6.79* (ca. 1.1H, d, J=8.3Hz, H5′), 6.89* (ca. 1.1H, d, J=1.4 Hz,
under the conditions shown in Table 1. Separation of the prod- H2′)], [8.05 (0.3H), 8.19 (0.3H), 8.23 (0.3H), 8.31* (1.1H)] (t,
ucts by centrifugal chromatography (CH2Cl2–EtOH=96:4) J=6.2Hz, NH). 13C-NMR (DMSO-d6) δ: 43.19, 43.28, 43.41*
gave 4g (57%) as a white solid. An analytical sample of 4g (Cα), [55.29* (on C3′), 55.35, 55.42* (on 5′), 55.51] (OCH3),
was obtained as colorless crystals by recrystallization from 111.38*, 111.51 (C2′), 111.67* (C5′), 119.22, 119.29, 119.36*
EtOH.
(C6′), 131.43, 131.61* (C1′), 147.73*, 147.78 (C4′), 148.55,*,
4g: mp 137–138°C (from EtOH). IR cm−1: 3444, 3421 (NH), 148.59 (C3′), 165.23, 165.36*, 165.61 (C2, 4), 167.77*, 168.30
1556, 1499 (C=N), 1206, 1157, 1115, 1031 (C–N or C–O), 924, (C6). (The observed 1H- and 13C-signals assignable to the
810 (1,2,4-trisubstituted benzene). 1H-NMR (CDCl3) δ: 3.78 predominant tautomer are asterisked.) Positive-ion FAB-MS
(9H, s, OCH3 on C4′ or C2′), 3.80 (9H, s, OCH3 on C2′ or m/z: 446 (M+H)+. HR-FAB-MS m/z: 446.1586 (Calcd for
C4′) 4.42, 4.52* (6H, brs, Hα), 5.05 (1H, brs, NH), 5.30 (2H, C21H25ClN5O4: 446.1595). Anal. Calcd for C21H24ClN5O4: C,
brs, NH), 6.36 (3H, brs, H5′), 6.43 (3H, brs, H3′), 7.16 (3H, d, 56.57; H, 5.43; N, 15.71. Found: C, 56.35; H, 5.42; N, 15.68.
J=8.3Hz, H6′). 13C-NMR (CDCl3) δ: 39.72 (Cα), 55.23 (OCH3
6-Chloro-N2,N4-bis(benzo[d][1,3]dioxol-5-ylmethyl)-
on C2′ or C4′), 55.31 (OCH3 on C4′or C2′), 98.32 (C3′), 1,3,5-triazine-2,4-diamine (3h)13) In a manner similar to
103.65 (C5′), 120.16 (C1′), 130.08 (C6′), 158.45 (C4′ or C2′), that for the preparation of 3f, the reaction of 1 and 2f only by
160.07 (C2′or C4′), 166.15 (C2, 4, 6). Positive-ion FAB-MS stirring for 30min at room temperature, product 3h was ob-
m/z: 577 (M+H)+. HR-FAB-MS m/z: 577.2789 (Calcd for tained in 96% yield as a white solid.
C30H37N6O6: 577.2775). Anal. Calcd for C30H36N6O6: C, 62.49;
3h: mp 225–226. IR cm−1: 3244 (NH), 1558 (C=N), 1280,
1
H, 6.29; N, 14.57. Found: C, 62.57; H, 6.29; N, 14.58.
1038 (C–N and/or C–O), 796 (C–Cl). H-NMR (DMSO-d6)
N2,N4,N6-Tris(benzo[d][1,3]dioxol-5-ylmethyl)-1,3,5-tri- δ: 4.31–4.35 [4H, m, Cα: including 4.33* (d, J=6.2Hz)],
azine-2,4,6-triamine (4h)5) Compound 4h was prepared 5.96*, 5.97, 5.98 (4H, s, H2′), 6.68-6.70 [1.1H, m, ArH:
from the reaction of 1 with piperonylamine (2h) (see ref. 5).
including 6.69* (brd, J=8.3Hz, H6′)], 6.72–6.78 [3H, m, ArH:
N2,N4,N6-Tris(3,4,5-trimethoxybenzyl)-1,3,5-triazine- including 6.77* (d, J=8.3Hz, H7′)], 6.83–6.88 [1.9H, m, ArH:
2,4,6-triamine (4i) (Entry 10) Compound 4i was prepared including 6.85* (brs, H4′)], [8.08 (0.5H), 8.21 (1.1H), 8.24
from the reaction of 1 with 3,4,5-trimethoxybenzylamine (2i) (1.1H), 8.33 (3.3H)] (t, J=6.2Hz, NH). 13C-NMR (DMSO-
under the conditions shown in Table 1. Separation of the prod- d6) δ: 43.14, 43.23, 43.36* (Cα), 100.76 (C2′), 107.82, 107.86*
ucts by centrifugal chromatography (CH2Cl2–EtOH=96:4) (C7′), 107.90, 108.00* (C4′), 120.26, 120.37, 120.46* (C6′),
gave 4i (63%) as a white solid. An analytical sample of 4i 132.92, 133.07, 133.13* (C5′), 146.03 (C3a′), 146.15 (C7a′),
was obtained as colorless crystals by recrystallization from 165.20, 165.30*, 165.56 (C2, 4), 167.81*, 168.33 (C6). (The
1
2-PrOH.
observed H- and 13C-signals assignable to the predominant
4i: mp 64–65°C (from 2-PrOH). IR cm−1: 3363 (NH), tautomer are asterisked.) Positive-ion FAB-MS m/z: 414
1590, 1560, 1498 (C=N), 1328, 1230, 1119 (C–N or C–O), (M+H)+. HR-FAB-MS m/z: 414.0974 (Calcd for C19H17ClN5O4:
1003 (C–O), 811 (1,2,3,5-tetrasubstituted benzene). H-NMR 414.0969). Anal. Calcd for C19H16ClN5O4·0.2H2O: C, 54.67 H,
1
(CDCl3) δ: 3.79 (18H, s, OCH3 on C3′, 5′), 3.82 (9H, s, OCH3 3.96; N, 16.78. Found: C, 54.63; H, 3.90; N, 16.84.
on C4′), 4.50 (6H, brs, Hα), 5.44, 5.50 (3H, brs, NH), 6.52
Preparation of N-Benzyl-4-chloro-6-isopropoxy-1,3,5-
(6H, s, H2′, 6′). 13C-NMR (CDCl3) δ: 44.93 (Cα), 55.99 triazin-2-amine (6a) (Table 2, Entry 1) Compound 6a
(OCH3 on C3′, 5′), 60.72 (OCH3 on C4′), 104.44 (C2′, 6′), was obtained from the reaction of 5b with 2a under the
134.88 (C1′), 137.03 (C4′), 153.25 (C3′, 5′), 166.13 (C2, 4, 6). conditions shown in Table 2. Thus, to a solution of interme-
Positive-ion FAB-MS m/z: 667 (M+H)+. HR-FAB-MS m/z: diate 5b (2.08g, 10.0mmol) in THF (150mL), benzylamine
667.3086 (Calcd for C33H43N6O9: 667.3092). Anal. Calcd for 2a (1.07g, 8.00mmol) and diisopropylethylamine (DIPEA,

836
Chem. Pharm. Bull.
Vol. 66, No. 8 (2018)
1.29g, 10.0mmol) were added and the reaction mixture was (brs, H1″), [5.53 (0.5H), 5.73 (0.2H), 5.84 (0.3H), 5.97* (1H)]
stirred for 2h at 0°C. After removal of the precipitated sol- (brs, NH), 7.20–7.35 (10H, m, H2′–6′). 13C-NMR (CDCl3)
ids (DIPEA·HCl salt), evaporation of the solvent gave crude δ: 21.89 (C2″, 3″), 44.53, 44.67* (Cα), 69.01, 69.48* (C1″),
compound 6a (2.71g, 9.74mmol, 97%) as a white powder. An 127.11, 127.31, 127.49 (C2′, 6′, 4′), 128.46 (C3′, C5′), 138.96*,
analytically pure sample of 6a was obtained as a white powder 139.21 (C1′), 167.15, 167.36* (C2, 4), 169.87, 170.21* (C6). (The
1
by recrystallization from acetonitrile (MeCN).
observed H- and 13C-signals assignable to the predominant
6a: mp 127–128°C (from MeCN). IR cm−1: 3262, 3110 tautomer are asterisked.) Positive-ion FAB-MS m/z: 350
(NH), 1638, 1527 (C=N), 1294, 1231, 1105 (C–N and/or C–O), (M+H)+. HR-FAB-MS m/z: 350.1989 (Calcd for C20H24N5O:
1
803 (C–Cl). H-NMR (CDCl3) δ: [1.31 (2H), 1.34* (4H)] (d, 350.1981). Anal. Calcd for C20H23N5O: C, 68.74; H, 6.63; N,
J=6.2Hz, H2″, 3″), [4.65 (0.7H), 4.67* (1.3H)] (d, J=6.2Hz, 20.04. Found: C, 68.73; H, 6.74; N, 20.00.
Hα), 5.20–5.30 (1H, m, H1″), [6.33 (0.3H), 6.78* (0.7H)] (brs,
6-Isopropoxy-N2,N4-bis(4-methoxybenzyl)-1,3,5-tri-
NH), 7.26–7.37 (5H, m, H2′–6′). 13C-NMR (CDCl3) δ: 21.63*, azine-2,4-diamine (7e) (Entry 4) Colorless needles. mp
21.67 (C2″, 3″), 44.99*, 45.07 (Cα), 71.66, 72.02* (C1″), 127.33, 132–134°C (from EtOH). IR cm−1: 3392, 3261, 3101 (NH),
127.62 (C2′, 6′) 127.66*, 127.72 (C4′), 128.70*, 128.74 (C3′, 1583, 1530 (C=N), 1238, 1170, 1108, 1030 (C–N and/or C–O).
C5′), 137.45 (C1′), 167.07 (C2), 169.81, 170.33, 170.40, 171.47 1H-NMR (CDCl3) δ: [1.26 (2H, brs), 1.32* (4H, d, J=5.5Hz)]
1
(C4, 6). (The observed H- and 13C-signals assignable to the (H2″, 3″), 3.78 (6H, brs, OCH3 on C4′), 4.48, 4.53* (4H,
predominant tautomer are asterisked.) Positive-ion FAB-MS brs, Hα), [5.13 (0.3H), 5.24* (0.7H)] (brs, H1″), [5.42 (0.3H),
m/z: 279 (M+H)+. HR-FAB-MS m/z: 279.0981 (Calcd for 5.55* (1.0H), 5.73 (0.7H)] (brs, NH), 6.83 (4H, d, J=7.6Hz,
C13H16ClN4O: 279.1013). Anal. Calcd for C13H15ClN4O: C, H3′, 5′), 7.20 (4H, d, J=7.6Hz, H2′, 6′). 13C-NMR (CDCl3)
56.02; H, 5.42; N, 20.10. Found: C, 55.96; H, 5.43; N, 19.93.
δ: 21.93 (C2″, 3″), 44.07, 44.15* (Cα), 55.22 (OCH3), 68.97*,
General Procedure for the Preparation of CS-Symmet- 69.38 (C1″), 113.87 (C3′, 5′), 128.96, 128.79* (C2′, 6′), 130.93*,
rical Benzylamine-Type TAZ Derivatives (7) (Table 2): 131.27 (C1′), 158.79 (C4′), 166.97, 167.26* (C2, 4), 169.89*,
1
Example 1 (No Base by MW): Synthesis of 6-Isopropoxy- 170.30 (C6). (The observed H- and 13C-signals assignable to
N2,N4-bis(4-methylbenzyl)-1,3,5-triazine-2,4-diamine (7b) the predominant tautomer are asterisked.) Positive-ion FAB-
(Entry 3) To a solution of intermediate 5b14) (416mg, MS m/z: 410 (M+H)+. HR-FAB-MS m/z: 410.2180 (Calcd for
2.0mmol) in dioxane (4mL) was added 2b (1.21g, 10.0mmol) C22H28N5O3: 410.2192). Anal. Calcd for C22H27N5O3: C, 64.53;
at room temperature. Then the mixture was subjected to H, 6.65; N, 17.10. Found: C, 64.51; H, 6.67; N, 17.04.
MW at 100°C (100W) for 45min with stirring. After addi-
N2,N4-Bis(3,4-dimethoxybenzyl)-6-isopropoxy-1,3,5-tri-
tion of water (50mL), the mixture was extracted with EtOAc azine-2,4-diamine (7f) (Entry 5) Colorless crystals. mp
(2×50mL). The combined organic layer was washed with 146–147°C (from MeCN). IR cm−1: 3397, 3248 (NH), 1553,
saturated aqueous NH4Cl solution and dried over MgSO4. 1516 (C=N), 1262, 1162, 1136, 1026 (C–N and/or C–O).
After evaporation of the solvent, the residue was recrystallized 1H-NMR (CDCl3) δ: [1.28 (2H, brs), 1.33 (4H, d, J=4.8Hz)]
from 2-PrOH to obtain analytically pure compound 7b as a (H2″, 3″), 3.80–3.90 (12H, m, OCH3 on C3′,4′), 4.56 (4H, brs,
colorless solid.
Hα), [5.15 (0.3H), 5.26 (0.7H)] (brs, H1″), [5.42 (1.4H), 5.59
7b: mp 142–143°C (from 2-PrOH). IR cm−1: 3347, 3239 (0.6H)] (brs, NH), 6.76–6.90 (6H, m, H2′, 5′, 6′). 13C-NMR
(NH), 1609, 1579 (C=N), 1158, 1104 (C–N and/or C–O). (CDCl3) δ: 21.94 (C2″, 3″), 44.62 (Cα), 55.82, 55.90* (OCH3),
1H-NMR (CDCl3) δ: [1.27 (brs), 1.31* (d, J=6.2Hz)] (6H, 69.11*, 69.59 (C1″), 110.78 (C2′), 111.12 (C5′), 119.64, 119.74*
H2″, 3″), 2.32 (6H, brs, CH3), 4.51, 4.55* (4H, brs, Hα), (C6′), 131.34*, 131.57 (C1′), 148.28 (C4′), 149.04 (C3′), 167.02,
1
[5.13 (0.3H), 5.23 (0.7H)] (brs, H1″), [5.38, 5.45 (0.6H), 5.61 167.33* (C2, 4), 170.28*, 170.31 (C6). (The observed H- and
(1.4H)] (brs, NH), 7.11 (4H, d, J=6.9Hz) (H3′, 5′), 7.17 (4H, 13C-signals assignable to the predominant tautomer are aster-
d, J=6.9Hz) (H2′, 6′). 13C-NMR (CDCl3) δ: 21.06 (CH3), isked.) Positive-ion FAB-MS m/z: 470 (M+H)+. HR-FAB-MS
21.94 (C2″, 3″), 44.40, 44.50* (Cα), 69.02*, 69.43 (C1″), 127.38, m/z: 470.2397 (Calcd for C24H32N5O5: 470.2403). Anal. Calcd
127.53* (C2′, 6′), 129.18 (C3′, 5′), 135.83*, 136.10 (C1′), 136.82 for C24H31N5O5: C, 61.39; H, 6.65; N, 14.92. Found: C, 61.25;
(C4′), 167.07, 167.35* (C2, 4), 169.93*, 170.30 (C6). (The H, 6.79; N, 14.91.
1
observed H- and 13C-signals assignable to the predominant
N2,N4-Bis(2,4-dimethoxybenzyl)-6-isopropoxy-1,3,5-
tautomer are asterisked.) Positive-ion FAB-MS m/z: 378 triazine-2,4-diamine (7g) (Entry 6) Colorless crystals.
(M+H)+. HR-FAB-MS m/z: 378.2284 (Calcd for C22H28N5O4: mp 134–136°C (from 2-PrOH). IR cm−1: 3417, 3248 (NH),
378.2294). Anal. Calcd for C22H28N5O4: C, 70.00; H, 7.21; N, 1612, 1592, 1526 (C=N), 1228, 1206, (C–N and/or C–O).
18.55. Found: C, 70.04; H, 7.22; N, 18.56.
1H-NMR (CDCl3) δ: [1.22–1.29 (2H), 1.29–1.40 (4H)] (brs,
N2,N4-Dibenzyl-6-isopropoxy-1,3,5-triazine-2,4-diamine H2″, 3″), [3.79 (8H), 3.82 (4H)] (s, OCH3), [4.55, 4.51 (brs),
(7a) (Entry 2) Compound 7a was prepared from the reaction 4.56* (d, J=5.5Hz)] (4H, Hα), 5.11*, 5.26, 5.35 (1H, brs, H1″),
of 5b with 2a under the conditions shown in Table 2 using the 5.34, 5.39, 5.50* (2H, brs, NH), 6.34–6.47 (4H, m, H3′, 5′),
above method. After the workup, separation of the products 7.13–7.22 (2H, m, H6′). 13C-NMR (CDCl3) δ: 21.99 (C2″, 3″),
by centrifugal chromatography (CH2Cl2–EtOH=98:2) gave 7a 40.03 (Cα), 55.25, 55.33 (OCH3), 68.69*, 69.06 (C1″), 98.43
(79%) as a white solid. An analytically pure sample of 7a was (C3′), 103.67 (C5′), 119.49*, 119.70 (C1′), 129.81, 130.10*,
obtained as colorless crystals by recrystallization from diiso- 130.25 (C6′), 158.50 (C2′), 160.29 (C4′), 166.95, 167.20* (C2,
1
propylether (2-Pr2O).
4), 169.88*, 170.13 (C6). (The observed H- and 13C-signals as-
7a: mp 117–119°C (from 2-Pr2O). IR cm−1: 3336, 3246 signable to the predominant tautomer are asterisked.) Positive-
(NH), 1615, 1508 (C=N), 1160, 1104 (C–N and/or C–O). ion FAB-MS m/z: 470 (M+H)+. HR-FAB-MS m/z: 470.2402
1H-NMR (CDCl3) δ: [1.24 (2H, brs), 1.28* (4H, d, J=5.5Hz)] (Calcd for C24H32N5O5: 470.2403). Anal. Calcd for C24H31N5O5:
(H2″, 3″), 4.55, 4.59* (4H, brs, Hα), [5.12 (0.3H), 5.21* (0.7H)] C, 61.39; H, 6.65; N, 14.92. Found: C, 61.21; H, 6.72; N, 14.68.

Vol. 66, No. 8 (2018)
Chem. Pharm. Bull.
837
N2,N4-Bis(benzo[d][1,3]dioxol-5-yllmethyl)-6-isopro- (C1″), 129.06 (C3′, 5′), 131.16*, 131.41 (C1′), 137.35 (C2′, 4′,
poxy-1,3,5-triazin-2,4-diamine (7h) (Entry 7) White solid. 6′), 166.48, 166.76, 167.10, 167.32* (C2, 4), 169.79, 170.17*,
1
mp 143–145°C (from EtOAc). IR cm−1: 3338, 3239, 3097 (NH), 170.70 (C6). (The observed H- and 13C-signals assignable to
1612, 1521 (C=N), 1246, 1232, 1102, 1038 (C–N and/or C–O). the predominant tautomer are asterisked.) Positive-ion FAB-
1H-NMR (CDCl3) δ: 1.28, 1.32* (6H, d, J=6.2Hz, H2″, 3″), MS m/z: 434 (M+H)+. HR-FAB-MS m/z: 434.2905 (Calcd for
4.46, 4.50*, 4.51 (4H, brs, Hα), 5.14, 5.24* (1H, brs, H1″), C26H36N5O: 434.2920). Anal. Calcd for C26H35N5O: C, 72.02;
5.36, 5.42*, 5.58 (2H, brs, NH), 5.93 (4H, s, H2′), 6.70–6.85 H, 8.14; N, 16.15. Found: C, 71.81; H, 8.34; N, 16.00.
(6H, m, H4′, 6′, 7′). 13C-NMR (CDCl3) δ: 21.96 (C2″, 3″),
Antiviral Activity Assay and Cytotoxicity Assay of Syn-
44.46, 44.58* (Cα), 69.14, 69.54* (C1″), 100.98 (C2′), 108.19 thesized TAZ Derivatives The anti-HSV-1 activities (EC50)
(C4′, 7′), 120.64 (C6′), 132.79*, 133.10 (C5′), 146.76 (C3a′), of the synthesized TAZ derivatives were measured by using
147.79 (C7a′), 166.99*, 167.05 (C2, 4 or C6), 167.30 (C6 or a plaque reduction assay9) and their cytotoxicity against Vero
1
C2, 4). (The observed H- and 13C-signals assignable to the cells (CC50) was also evaluated as our previous description.5)
predominant tautomer are asterisked.) Positive-ion FAB-MS The results are summarized in Table 3 together with data
m/z: 438 (M+H)+. HR-FAB-MS m/z: 438.1779 (Calcd for for aciclovir.15) Calculated logP values10) for the compounds
C22H24N5O5: 438.1777). Anal. Calcd for C22H23N5O5: C, 60.40; are also shown in Supplementary Materials (Fig. S1). There
H, 5.30; N, 16.01. Found: C, 60.42; H, 5.27; N, 16.00.
were few distinct correlations between logP values by using
6-Isopropoxy-N2,N4-bis(3,4,5-trimethoxybenzyl)-1,3,5- ChemBioDraw Ultra v.14.0 and anti-HSV-1 activity (EC50).
triazine-2,4-diamine (7i) (Entry 8) Colorless crystals. mp
148–150°C (from 2-PrOH). IR cm−1: 3315, 3246 (NH), 1586,
Acknowledgment The authors would like to thank Ms.
1542 (C=N), 1225, 1159, 1334, 1099 (C–N and/or C–O). Kanae Yamada, Ms. Shoko Tomonaga and Ms. Junko Matsu-
1H-NMR (CDCl3) δ: [1.29 (brs), 1.33 (d, J=4.8Hz)] (6H, H2″, yama for their valuable technical assistance.
3″), 3.82 (18H, brs, OCH3), 4.53*, 4.56 (4H, m, Hα), [5.16
(0.25H, brs), 5.26* (0.75H, brs)] (H1″), [5.45*, 5.52 (1.5H), 5.67
Conflict of Interest The authors declare no conflict of
(0.5H)] (brs, NH), 6.54 (4H, brs, H2′, 6′). 13C-NMR (CDCl3) interest.
δ: 21.91 (C2″, 3″), 40.91, 44.93, 44.98, 45.09* (Cα), 56.07
(OCH3 on C3′, 5′), 60.79 (OCH3 on C4′), 69.24*, 69.60 (C1″),
Supplementary Materials The online version of this ar-
104.39*, 104.70 (C2′, 6′), 134.48*, 134.66 (C1′), 137.16 (C3′, ticle contains supplementary materials.
5′), 153.34 (C4′), 167.11, 167.37* (C2, 4), 169.98*, 170.27 (C6).
1
(The observed H- and 13C-signals assignable to the predomi-
References and Notes
1) Clercq E. D., “Advances in Pharmacology Vol 67: Antiviral
nant tautomer are asterisked.) Positive-ion FAB-MS m/z: 530
(M+H)+. HR-FAB-MS m/z: 530.2621 (Calcd for C26H36N5O7:
530.2615). Anal. Calcd for C26H35N5O7: C, 58.97; H, 6.66; N,
13.22. Found: C, 58.94; H, 6.74; N, 13.20.
Agents,” Elsevier Academic Press, London, 2013, and related refer-
ences cited therein.
2) Duran A. M., Meiler J., Comput. Struct. Biotechnol. J., 8,
e201308004 (2013).
3) Contreras J.-M., Sippl W., “The Practice of Medicinal Chemistry”
3rd ed., ed. by Wermuth C. G., Elsevier Academic Press, London,
2008, pp. 380–414 and related references cited therein.
4) Mibu N., Yokomizo K., Koga A., Honda M., Mizokami K., Fujii H.,
Ota N., Yuzuriha A., Ishimaru K., Zhou J., Miyata T., Sumoto K.,
Chem. Pharm. Bull., 62, 1032–1040 (2014).
N2,N4-Bis(3,4-dimethylbenzyl)-6-isopropoxy-1,3,5-tri-
azine-2,4-diamine (7j) (Entry 9) Colorless solid. mp
119–123°C (from EtOH). IR cm−1: 3397, 3247, 3105 (NH),
1614, 1577, 1523 (C=N), 1166, 1146, 1104 (C–N and/or C–O).
1H-NMR (CDCl3) δ: [1.28 (2H, brs), 1.32* (4H, d, J=5.5Hz)]
(H2″, 3″), 2.23 (12H, brs, CH3), 4.49, 4.54* (4H, brs, Hα), [5.14
(0.3H), 5.25* (0.7H)] (brs, H1″), [5.38* (1.4H), 5.52 (0.6H)]
(brs, NH), 7.02–7.12 (6H, m, H2′, 5′, 6′). 13C-NMR (CDCl3)
δ: 19.36 (CH3 on C4′), 19.69 (CH3 on C3′), 21.95 (C2″, 3″),
44.41, 44.52* (Cα), 68.99, 69.42* (C1″), 124.86, 125.04* (C6′),
128.74, 128.92* (C2′), 129.73 (C5′), 135.47 (C4′), 136.22*,
136.48 (C1′), 136.71 (C3′), 167.03, 167.33* (C2, 4), 169.93,
5) Mibu N., Yokomizo K., Yuzuriha A., Otsubo M., Kawaguchi Y.,
Sano M., Sakai I., Nakayama K., Zhou J.-R., Sumoto K., Hetero-
cycles, 94, 1653–1677 (2017) and related references cited therein.
6) Some of the tri-substituted TAZ derivatives described in this paper
showed a complicated 13C-NMR signal pattern because of their ke-
to-enol tautomeric isomers in solutions. Compounds (3b, 4c–e, 6a,
7a, 7b, 7e–k) that have sec-benzylamino groups on a TAZ template
are examples of TAZ derivatives with such a signal pattern. These
compounds showed the presence of two tautomeric isomers in solu-
tion. Thus, signals that appeared in the 13C-NMR spectra of C3-type
compounds (4c–e) are fully consistent with the tautomeric mixture
1
170.21* (C6). (The observed H- and 13C-signals assignable to
the predominant tautomer are asterisked.) Positive-ion FAB-
MS m/z: 406 (M+H)+. HR-FAB-MS m/z: 406.2594 (Calcd for
C24H32N5O: 406.2607). Anal. Calcd for C24H31N5O: C, 71.08;
H, 7.70; N, 17.27. Found: C, 71.03; H, 7.70; N, 17.27.
1
of two isomers shown below (A and B). We showed examples of H-
and 13C-NMR spectra of some tri-substituted TAZ derivatives (3–7)
6-Isopropoxy-N2,N4-bis(2,4,6-trimethylbenzyl)-1,3,5-
triazine-2,4-diamine (7k) (Entry 10) Colorless crystals.
mp 146–147°C (from EtOH). IR cm−1: 3252, 3105, 2975
(NH), 1619, 1577, 1519 (C=N), 1172, 1017 (C–N and/or C–O).
1H-NMR (CDCl3) δ: [1.26 (d, J=5.5Hz), 1.35*, 1.43 (brs)]
(6H, H2″, 3″), 2.26, 2.27, 2.31* (6H, brs, CH3 on C4′), 2.36,
2.37 (12H, brs, CH3 on C2′, 6′), 4.42, 4.55, 4.58*, 4.66 (4H,
brs, Hα), 4.68, 4.86* (2H, brs, NH), [5.09 (0.25H), 5.24*
(0.6H), 5.43 (0.15H)] (brs, H1″), 6.86, 6.88 (4H, brs, H3′, 5′).
13C-NMR (CDCl3) δ: 19.56 (CH3 on C2′, 6′), 20.87 (CH3 on
C4′), 21.96 (C2″, 3″), 39.31*, 39.43 (Cα), 68.95, 69.38*, 69.79
in Supplementary Materials (Fig. S2) for readers’ convenience.

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Chem. Pharm. Bull.
Vol. 66, No. 8 (2018)
7) For example, see: Cooke G., Rotello V. M., Chem. Soc. Rev., 31,
12) We have recently reported the results of calorimetric experiments
on sugar recognition properties of this compound. J. Therm. Anal.
Calorim., (2017), submitted.
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275–286 (2002) and also see the ref. 8.
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9) Schinazi R. F., Peters J., Williams C., Chance D., Nahmias A. J.,
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10) Calculated logP values were calculated by using ChemBioDraw
Ultra v.14.0.
11) Mibu N., Yokomizo K., Murakami K., Ono Y., Ishimaru M., Otsubo
M., Inao H., Ono Y., Zhou J.-R., Sumoto K., Chem. Pharm. Bull., 15) Ikeda T., Yokomizo K., Okawa M., Tsuchihashi R., Kinjo J., Nohara
64, 1769–1780 (2016).
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