sym-triazine derivatives. 2. Synthesis, properties, and structure of 2-oxo-1,2-dihydro-sym-triazines

Article abstract of DOI:10.1023/A:1015631203046

Previously unreported 2-oxo-1,2-dihydro-sym-triazines have been prepared and their alkylation reactions have been studied. It was found that, independently of the structure and nature of the substituent in positions 4 and 6 of the triazine ring or the str

Full text of DOI:10.1023/A:1015631203046

Chemistry of Heterocyclic Compounds, Vol. 38, No. 3, 2002
sym
-TRIAZINE DERIVATIVES.
2*. SYNTHESIS, PROPERTIES,
AND STRUCTURE OF 2-OXO-
-sym-
TRIAZINES
1,2-DIHYDRO
S. N. Mikhailichenko1, A. A. Chesniyuk1, V. E. Zavodnik2, S. I. Firgand3,
L. D. Konyushkin3, and V. N. Zaplishny1
Previously unreported 2-oxo-1,2-dihydro-sym-triazines have been prepared and their alkylation
reactions have been studied. It was found that, independently of the structure and nature of the
substituent in positions 4 and 6 of the triazine ring or the structure of the alkyl halide used, the reaction
occurs regioselectively at the oxygen atom. The stereostructure of the 2-oxo-1,2-dihydro-sym-triazines
was investigated by X-ray analysis and it was shown that they exist as dimers in the crystalline state.
Keywords: 2-oxo-1,2-dihydro-sym-triazines, alkylation, X-ray analysis.
We have recently described [1] some novel quaternary trimethylammonium salts based on various
2-chloro-4,6-R,R'-sym-triazines derivatives and studied certain of their reactions. Attempts to prepare
mercaptotriazines from quaternary salts by treatment with an aqueous solution of Na2S were not successful and
2-oxo-1,2-dihydro-sym-triazines were unexpectedly obtained. In this work we have shown that the latter are also
formed readily and in good yields (62-84%) by treatment of the quaternary salts 1a-f with aqueous base
solution. It is likely that the oxo compounds are obtained as a result of the isomerization of 2-hydroxy-sym-
triazines formed through substitution of the trimethylammonium group by hydroxide anion.
_
N+Me3CI
O
_
OH
HN
N
N
N
R
N
R'
R
N
R'
2a–f
1a–f
1, 2 a R = R' = N(CH2CH2)2O; b R = R' = N(CH2)5; c R = OMe, R' = N(CH2CH2)2O;
d R = R' = OMe; e R = R' = SPh; f R = R' = NHCH2Ph
__________________________________________________________________________________________
1
Kuban State Agricultural University, Krasnodar 350044, Russia; e-mail: vlad.zpl@mail.ru.
2 L. Ya. Karpov Physico-Chemical Science Research Institute, Moscow 103064, Russia. N. D. Zelinsky
Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913, Russia. Translated from
Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 326-334, March 2002. Original article submitted July 18,
2000; revision submitted February 11, 2001.
3
292
0009-3122/02/3803-0292$27.00©2002 Plenum Publishing Corporation

A similar isomerization has been recorded [2] for the Friedel–Crafts reaction of toluene with
6-substituted 2,4-dichloro-1,3,5-triazines and also for the reaction of 4,6-dichloro-2-methoxytriazine with ethyl
sodium malonate [3]. It is of interest that, according to [4], cyanuric acid exists principally in the enol form in
basic medium but acid hydrolysis of 2-alkoxy-4,6-bisdialkylamino-sym-triazines gives the corresponding
2-hydroxy-4,6-bisdialkylamino-sym-triazines [5, 6].
The composition and structure of the compounds obtained was confirmed by elemental analysis data, by
1
IR and mass spectrometry, and also by H NMR spectroscopy (Table 1). The IR spectra show strong and
medium intensity, broad absorption bands which are typical of NH stretching vibrations in the region
3430-3440, the C=O groups at 1670-1690, and also a series of absorption bands in the range 1640-1510 cm-1
which are typical of the C=C and conjugated C=N bonds (Table 1).
1
The H NMR spectra of the synthesized compounds show a broad singlet for an NH group at
10.52-13.05 ppm and also signals for the protons of the substituents in the 4 and 6 positions of the triazine ring
(Table 1).
Since there is only fragmentary data for the synthesis of 2-oxo-1,2-dihydro-sym-triazines in the
literature [2, 3] and their properties have been little studied we have examined the alkylation of these
compounds in this report.
The reaction of 2-oxo-1,2-dihydro-sym-triazines 2a,e with alkyl halides was carried out in acetonitrile or
DMF in the presence of potassium hydroxide with an equimolar ratio of the reagents.
_
+
OR''
O K
HalR''
N
N
N
N
N
2a,e
R'
R'
R
N
R
3a–d
3a-c R = R' = N(CH2CH2)2O, d R = R' = SPh; a, d R''= Me; b R'' = C3H7, c R'' = C4H9
TABLE 1. Characteristics for the Compounds Synthesized
Found, %
——————
Calculated, %
Com-
pound
Empirical
formula
mp, °С
Yield, %
С
N
Н
С11Н17N5O3
С13Н21N5O
С8Н12N4O3
С5Н7N3O3
49.57
49.42
26.45
26.20
6.63
6.41
310-311
220
62
84
62
70
70
80
65
50
60
64
2a
2b
2c
2d
2e
2f
59.52
26.85
8.29
59.29
26.59
8.04
45.41
45.28
26.75
26.40
5.89
5.70
239-241
202-203
231-232
>400
38.37
26.99
4.65
38.22
26.74
4.49
C15H11N3OS2
C17H17N5O
C12H19N5O3
C14H23N5O3
С15Н25N5O3
C16H13N3OS2
57.72
57.49
13.54
13.41
3.77
3.54
66.58
22.91
5.82
66.43
22.79
5.58
51.47
51.23
25.13
24.90
7.02
6.81
154-155
146-147
98-99
3a
3b
3c
3d
54.52
25.05
8.48
54.35
24.90
8.24
55.87
55.71
21.92
21.66
7.88
7.79
58.78
12.99
4.23
55-56
58.69
12.83
4.00
_______
* Compound 2e found: S 20.57%, calculated: S 20.46%; Compound 3d
found: S 19.75%, calculated: S 19.58%.
293

TABLE 2. Spectroscopic Characteristics for the Compounds Synthesized*
Com-
IR spectrum, ν, cm-1
C=N, C=C
1H NMR spectrum, δ, ppm, (spin-spin coupling, J, Hz)*2
pound
N–H
440
C=O
COC
CH3
NCH2, OCH2
OCH3, s
NH, br. s
Other protons
590, 1560
150, 1070
—
—
—
—
—
3.53-3.73 (16Н, m)
3.55-3.70 (16Н, m)
—
3.9
3.89
—
10.52
11.45
12.30
13.05
—
—
—
—
2a
2b
2c
2d
3a
3430 1670 1630, 1570, 1510 1100, 1140
3440 1690 1630, 1570, 1500 1190, 1120
3430 1670 1640, 1570, 1520 1230, 1140
—
—
7.29-7.50 (10Н, m, H(Ar)
—
—
—
—
—
—
1560, 1520
1570, 1530
1570, 1520
1130, 1090,
3.56-3.78 (16Н, m)
3.81
—
1050, 1030
1140, 1100, 1060 0.72 (3Н, t, J = 9) 3.58-3.73 (16Н, m);
4.16 (2Н, t, J = 6, OCH2)
—
—
—
—
3b
3c
1.64-1.78 (2Н, m,
OCH2CH2CH3)
1170, 1140,
0.97 (3Н, t, J = 9) 3.58-3.73 (16Н, m);
1.37-1.50 (2Н; m,
1100, 1030
4.20 (2Н, t, J = 8, OCH2)
СH2CH3); 1.61-1.71
(2Н, m, –CH2CH2CH3)
—
—
1570, 1520
1160, 1140,
1055, 1015
—
—
3.72
—
3d
7.24-7.43 (10Н, m, H (Ar)
_______
* Mass spectroscopic data can be obtained from the authors.
*2 1H NMR spectrum, ppm, J (Hz): 3b: 0.72 (3H, t, J = 9, CH3); 3c: 0.97 (3H, t, J = 9, CH3).

It was found that, independently of the nature of the halogen derivative, the solvent, and the reaction
temperature, the reaction takes place highly regioselectively at the oxygen atom to give the 4,6-disubstituted
2-alkoxy-sym-triazines 3a-d in 60-70% yield. The determining factor in this regioselectivity is evidently the
localization of the negative charge on the oxygen atom in the intermediate potassium salt. The structure of the
4,6-disubstituted 2-alkoxy-sym-triazines 3a-d was confirmed by IR, mass spectroscopic, and 1H NMR data (Table 2).
In the IR spectra of compounds 3a-d the absorption bands typical of C=O and N–H bonds are absent but
a series of bands are seen at 1015-1170 cm-1, characteristic of the stretching bands of ethers. The 1H NMR spectra
show no broad signal for an NH group proton but show the presence of alkoxy group proton signals (Table 2).
In order to confirm the structure and to study the geometry of the molecule in detail we undertook an X-ray
investigation of compounds 2a and 2c. Projections of the steric models for the molecules are given in Figure 1
and the atomic coordinates, interatomic distances, and valence and torsional angles are presented in Tables 3-5.
TABLE 3. Atomic Coordinates* (×104) for Compounds 2a,c
Atom
x
y
z
U (eq)
Compound 2c
1229(4)
8455(5)
8401(4)
3646(5)
5974(5)
8361(5)
5966(5)
2698(8)
2275(8)
2193(8)
2696(8)
5244(6)
7608(6)
7507(6)
7595(8)
О(1)
О(2)
О(3)
N(1)
N(2)
N(3)
N(4)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
6966(5)
-660(5)
5557(5)
5005(6)
2071(6)
2495(6)
5441(5)
7221(8)
8015(9)
4810(8)
3848(9)
4108(7)
1208(8)
4526(7)
7777(9)
5770(4)
1694(4)
-888(4)
3192(4)
2502(4)
406(4)
67(1)
71(1)
60(1)
57(1)
54(1)
56(1)
49(1)
63(2)
62(2)
59(2)
59(2)
46(1)
53(1)
49(1)
62(2)
1131(4)
308(6)
4560(6)
5920(6)
4488(6)
2252(5)
1555(5)
254(5)
-1123(8)
Compound 2a
2524(5)
4800(4)
1042(4)
2475(5)
3637(5)
3702(5)
2488(4)
2552(5)
1635(7)
2477(9)
3446(7)
2633(8)
2882(5)
4058(6)
2917(5)
2401(9)
2346(8)
1401(9)
1397(8)
O(1)
O(2)
O(3)
N(1)
N(2)
N(3)
N(4)
N(5)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
102(5)
9574(5)
3993(5)
3199(5)
6443(5)
7321(5)
4034(5)
4945(5)
1137(7)
-35(8)
2086(7)
3623(7)
4616(6)
7815(6)
5421(6)
6507(8)
5718(8)
2439(8)
3006(8)
-156(2)
3572(2)
7759(3)
1775(3)
2606(3)
4640(3)
3751(3)
5737(3)
1782(4)
985(4)
56(1)
58(1)
61(1)
44(1)
42(1)
40(1)
38(1)
39(1)
46(1)
54(1)
51(1)
51(1)
36(1)
40(1)
36(1)
52(1)
55(1)
61(2)
53(1)
-124(4)
607(4)
2742(3)
3574(3)
4698(3)
6743(4)
7838(4)
6884(4)
5716(4)
_______
* Hydrogen atom coordinates can be obtained from the authors.
295

Fig. 1. Projections of the molecules 2a,c.
TABLE 4. Interatomic Distances in the Molecules 2a,c
Bond
d, Å
Bond
d, Å
Compound 2a
Compound 2c
O(1)–C(3)
1.424(5)
1.429(6)
1.250(5)
1.414(6)
1.414(6)
1.343(5)
1.459(6)
1.462(6)
1.328(5)
1.335(5)
1.361(5)
1.385(5)
1.317(5)
1.350(5)
1.351(5)
1.467(6)
1.474(6)
1.503(7)
1.481(7)
1.486(7)
1.495(7)
O(1)–C(3)
1.420(6)
1.425(6)
1.233(5)
1.320(5)
1.441(6)
1.339(5)
1.451(6)
1.466(6)
1.323(5)
1.355(5)
1.329(6)
1.377(5)
1.288(5)
1.374(5)
1.496(8)
1.504(8)
O(1)–C(2)
O(2)–C(6)
O(3)–C(9)
O(3)–C(10)
N(1)–C(5)
N(1)–C(1)
N(1)–C(4)
N(2)–C(6)
N(2)–C(5)
N(3)–C(7)
N(3)–C(6)
N(4)–C(7)
N(4)–C(5)
N(5)–C(7)
N(5)–C(8)
N(5)–C(11)
C(1)–C(2)
C(3)–C(4)
C(8)–C(9)
C(10)–C(11)
O(1)–C(2)
O(2)–C(6)
O(3)–C(7)
O(3)–C(8)
N(1)–C(5)
N(1)–C(1)
N(1)–C(4)
N(2)–C(5)
N(2)–C(6)
N(3)–C(7)
N(3)–C(6)
N(4)–C(7)
N(4)–C(5)
C(1)–C(2)
C(3)–C(4)
296

In crystalline states, compounds 2a,c exist as dimers which are joined via the oxo and amino group by a
hydrogen bond, the length of which is 1.77Å in compound 2a and 1.836 Å in 2c. This dimerization is also likely
to be the reason for the high melting points, poor solubility, and low reactivity of the compounds 2. Moreover,
incomplete conjugation leads to deformation of the triazine ring. The greatest deformation of this ring occurs
with different substituents at positions 4 and 6.
The longest bond in the triazine ring in both compounds is the N(3)–C(6) bond which is 1.377 in
compound 2c and 1.385 Å in 2a. The bond length of the remaining C–N and C=N bonds in compound 2a varies
in the range 1.317 (C(7)–N(4)) to 1.361 Å (C(7)–N(3)) while the length of such bonds in the unsubstituted
sym-triazine is 1.337 Å, according to the authors of [8]. The valence angles of 2a are also deformed, the greatest
distortion of the angles are at atoms N(4) (116.0°), N(2) (115.9°), and C(5) (127.0°).
Compound 2c contains different substituents at positions 4 and 6 of the triazine ring which leads to a
still greater deformation of the valence angles and changes the bond lengths in the triazine ring. The length of
the conjugated bonds in this compound varies in the range 1.288 (C(7)–N(4)) to 1.355 Å (C(6)–N(2)) and the
valence angles from 113.6° (C(7)–N(4)–C(5)) to 126.9° (N(2)–C(5)–N(4)). Such a distortion in the bond lengths and
valence angles in the triazine ring of compound 2c is evidently associated with partial conjugation of the
unshared electron pair of the oxygen atom in the methoxy group with the multiple C(7)–N(4) bond and with the
TABLE 5. Valence Angles in Compounds 2a,c
Angle
Angle
Compound 2c
ϕ, deg.
ϕ, deg.
Compound 2a
С(3)–O(1)–C(2)
110.5(3)
С(3)–О(1)–С(2)
109.7 (4)
117.4 (4)
124.1 (4)
123.2 (4)
112.6 (4)
116.6 (4)
120.4 (4)
113.6 (4)
109.8 (4)
110.0 (5)
112.1 (5)
109.4 (5)
117.8 (4)
126.9 (4)
115.3(4)
123.1(5)
118.8(4)
118.1(4)
122.2(4)
124.4(4)
113.4(4)
C(9)–O(3)–C(10)
(5)–N(1)–C(1)
109.4(4)
123.2(3)
123.3(3)
113.1(3)
115.9(3)
119.9(4)
116.0(3)
121.0(4)
116.6(3)
114.0(4)
110.6(4)
111.4(4)
111.9(4)
110.5(4)
116.7(3)
127.0(4)
116.3(3)
122.5(4)
117.2(4)
120.3(4)
119.2(3)
121.0(4)
119.9(4)
111.9(4)
111.9(4)
111.9(4)
112.0(5)
111.5(4)
С(7)–O(3)–C(8)
C(5)–N(1)–C(1)
С(5)–N(1)–C(4)
C(1)–N(1)–C(4)
C(5)–N(2)–C(6)
C(7)–N(3)–C(6)
C(7)–N(4)–C(5)
N(1)–C(1)–C(2)
O(1)–C(2)–C(1)
O(1)–C(3)–C(4)
N(1)–C(4)–C(3)
N(2)–C(5)–N(1)
N(2)–C(5)–N(4)
N(1)–C(5)–N(4)
O(2)–C(6)–N(2)
O(2)–C(6)–N(3)
N(2)–C(6)–N(3)
N(4)–C(7)–O(3)
N(4)–C(7)–N(3)
O(3)–C(7)–N(3)
C(5)–N(1)–C(4)
C(1)–N(1)–C(4)
C(6)–N(2)–C(5)
C(7)–N(3)–C(6)
C(7)–N(4)–C(5)
C(7)–N(5)–C(8)
C(7)–N(5)–C(11)
C(8)–N(5)–C(11)
N(1)–C(1)–C(2)
O(1)–C(2)–C(1)
O(1)–C(3)–C(4)
N(1)–C(4)–C(3)
N(2)–C(5)–N(1)
N(2)–C(5)–N(4)
N(1)–C(5)–N(4)
O(2)–C(6)–N(2)
O(2)–C(6)–N(3)
N(2)–C(6)–N(3)
N(4)–C(7)–N(5)
N(4)–C(7)–N(3)
N(5)–C(7)–N(3)
N(5)–C(8)–C(9)
O(3)–C(8)–C(9)
O(3)–C(9)–C(8)
O(3)–C(10)–C(11)
(5)–C(11)–C(10)
297

TABLE 6. Torsional Angles in Compounds 2a,c
Angle
Compound 2a
θ, deg
Angle
Compound 2с
θ, deg
C(4)–N(1)–C(1)–C(2)
C(5)–N(1)–C(1)–C(2)
C(3)–O(1)–C(2)–C(1)
N(1)–C(1)–C(2)–O(1)
C(2)–O(1)–C(3)–C(4)
C(1)–N(1)–C(4)–C(3)
C(5)–N(1)–C(4)–C(3)
O(1)–C(3)–C(4)–N(1)
C(7)–N(5)–C(8)–C(9)
C(11)–N(5)–C(8)–C(9)
C(10)–O(3)–C(9)–C(8)
N(5)–C(8)–C(9)–O(3)
C(9)–O(3)–C(10)–C(11)
C(7)–N(5)–C(11)–C(10)
C(8)–N(5)–C(11)–C(10)
O(3)–C(10)–C(11)–N(5)
-50.7
136.2
-58.5
53.8
59.7
51.5
C(4)–N(1)–C(1)–C(2)
C(5)–N(1)–C(1)–C(2)
C(3)–O(1)–C(2)–C(1)
N(1)–C(1)–C(2)–O(1)
C(2)–O(1)–C(3)–C(4)
C(1)–N(1)–C(4)–C(3)
C(5)–N(1)–C(4)–C(3)
O(1)–C(3)–C(4)–N(1)
-54.6
123.0
-61.7
58.9
60.0
51.7
-135.5
-55.6
168.6
-44.3
-62.0
53.3
-125.9
-54.2
61.8
-167.5
44.0
-52.7
redistribution of electron density in the ring. These effects may also apparently explain somewhat decreased N–H
(0.936 Å) and C=O (1.233 Å) bond lengths in compound 2c when compared with the lengths of the
corresponding bonds in compound 2a (1.004 and 1.25 Å).
It was of interest to note that the morpholine ring in position 6 of compound 2a has a half chair
conformation. Moreover, the lengths of the single C–C bonds in this fragment is somewhat shorter than the
mean C–C bond lengths in aliphatic cyclic amines and the valence angles are also somewhat distorted (Table 3).
The same substituent in position 4 of the triazine ring has a chair conformation with a smaller distortion of bond
lengths and valence angles when compared with the mean values for similar compounds (Tables 4-6).
In compound 2c the morpholine substituent at position 6 of the triazine ring is also found in a half chair
conformation, moreover its torsional angles are virtually identical with those for the substituent in position 6 of
compound 2a (Tables 5, 6). The methyl group carbon atom is situated in the plane of the triazine ring.
Hence these novel 2-oxo-1,2-dihydro-sym-triazines have been synthesized and their reactivities towards
alkylation studied. The structure determination has identified their tendency towards dimerization in the
crystalline state via the formation of N–H···O=C hydrogen bonds.
EXPERIMENTAL
IR spectra were recorded for vaseline oil suspension of the samples on a Specord IR-75 instrument.
1H NMR spectra were taken on a Bruker WM-250 spectrometer (250 MHz) for sample solutions in DMSO-d6.
Mass spectra were recorded on a Finnigan MAT INCOS50 instrument (70 eV). Monitoring of the reaction
course and the purity of the products obtained was performed using TLC on Silufol UV-254 plates in the system
acetone-hexane (1: 1).
X-Ray Structural Investigation of Compounds 2a,c. Prismatic crystals grown from ethanol solution.
Compound 2a. C11H17N5O3. Unit cell parameters: a = 6.877 (1), b = 7.834 (2), c = 11.762 (2) Å;
α = 92.08 (3), β = 100.66 (3), γ = 99.80 (3)°; Z = 2; d = 1.450 Mg/m3; V = 612.1 (2) Å3. Space group triclinic, P-1
Compound 2c. C8H12N4O3. Unit cell parameters: a = 7.023 (1), b = 8.573 (2), c = 9.439 (2) Å;
α = 69.07 (3), β = 76.33 (3), γ = 67.38 (3)°; Z = 2; d = 1.448 Mg/m3; V = 486.7 (1) Å3. Space group triclinic,
P-1. Experimental data was obtained on an Enraf-Nonius CAD 4 automatic diffractometer using
298

MoKα-radiation with a β-filter and θ/2θ scanning. In all, 944 reflections were obtained with I 2σ (I). The
>
structure was solved by a direct method using the SHELXTL computer program [8] and refined in the
anisotropic (isotropic for hydrogen) approximation to difference factors of R = 0.0390, Rw = 0.0439 for 2a and
R = 0.0469, Rw = 0.0470 for 2c.
2-Oxo-1,2-dihydro-4,6-R,R'-sym-triazines (2a-f). A mixture of the 2-trimethylammonium-4,6-R,R'-
sym-triazine (9 mmol), prepared as in method [1], and NaOH (18 mmol) was stirred at a temperature of 40°C for
3-5 h. The reaction mixture was then acidified with acetic acid to pH 6.5-5.0 and the precipitated product 2 was
filtered off, washed with water, and purified by crystallization from alcohol.
2-Alkoxy-4,6-R,R'-sym-triazines (3a-d). A 10% aqueous solution of KOH (1.5 ml, 1.9 mmol) was
added rapidly to a solution of the compound 2a-f (1.9 mmol) in DMF (10-15 ml). The solution obtained was
then treated with the alkyl halide (1.9 mmol) with stirring and the mixture was held for from 3 h to 2 days at
25-60°C. The contents were diluted with twice the quantity of water and the precipitated product was filtered
off, washed with water, and recrystallized from a mixture of hexane and benzene (3:1).
In the case of using acetonitrile as solvent, after completion of the reaction the acetonitrile was
evaporated in vacuo and the precipitate was filtered off and worked up as described above.
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