Heterocyclization reactions of 2-(2-propynylthio)-4(1H)-quinazolinone derivatives when treated with electrophilic and nucleophilic reagents

Article abstract of DOI:10.1023/B:COHC.0000003532.58469.cc

Reaction of the potassium salt of 2-thioquinazolin-4-one with propargyl halides leads to formation of 2-propargylthioquinazolin-4-one derivatives, which undergo heterocyclization when they are treated with electrophilic or nucleophilic reagents and, depen

Full text of DOI:10.1023/B:COHC.0000003532.58469.cc

Chemistry of Heterocyclic Compounds, Vol. 39, No. 8, 2003
HETEROCYCLIZATION REACTIONS
OF 2-(2-PROPYNYLTHIO)-4(1H)-QUINAZOLINONE
DERIVATIVES WHEN TREATED WITH
ELECTROPHILIC AND NUCLEOPHILIC REAGENTS
Yu. L. Zborovskii1, V. V. Orysyk2, A. A. Dobosh2, V. I. Staninets1, V. V. Pirozhenko1,
and A. N. Chernega1
Reaction of the potassium salt of 2-thioquinazolin-4-one with propargyl halides leads to formation of
2-propargylthioquinazolin-4-one derivatives, which undergo heterocyclization when they are treated
with electrophilic or nucleophilic reagents and, depending on the nature of the cyclization agent, leads
to formation of tricyclic systems with angular or linear structure.
Keywords: angular and linear triazoloquinazolinones, electrophilic and nucleophilic reagents,
heterocyclization.
Derivatives of thiazolo[2,3-b]quinazolinone with linear structure, obtained by condensation of the
methyl ester of anthranilic acid with propargyl isothiocyanates, exhibit high physiological activity: they have
anti-inflammatory and sedative properties, and are muscle relaxants and tranquilizers [1].
With the aim of developing new methods for obtaining derivatives of thiazoloquinazolinone, we studied
heterocyclization of 2-propargylthioquinazolin-4-ones when treated with a number of electrophilic and
nucleophilic reagents. The latter, depending on their nature, enable us to obtain condensed heterocyclic systems
with both linear and angular structure.
Thus we established that the reaction of quinazolinone 2 with bromine or iodine in acetic acid leads to
formation of hydropolyhalides of the angular 2-halomethylidenedihydrothiazoloquinazolin-5-one 3a,b.
Treatment of the latter with an aqueous solution of sodium acetate yields the corresponding bases 4a,b.
Such cyclization can also be carried out by treatment with sodium ethoxide. In this case,
thiazoloquinazolinone 5 is formed, which also has an angular structure.
Using conc. H2SO4 as the cyclization agent leads to formation of thiazoloquinazolinone 6, with linear
structure.
The different directions of the considered reactions is probably due to differences in the mechanisms of
these conversions.
Sulfuric acid forms a salt with participation of the more basic nitrogen atom N(1) of compound 2, which
blocks this nucleophilic reaction center in the cyclization step and ultimately leads to the linear
dihydrothiazoloquinazolinone 7, which then is isomerized to compound 6. In contrast, sodium methoxide
__________________________________________________________________________________________
1
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev 02094; e-mail:
2
iochkiev@ukrpack.net. Uzhgorod National University, Uzhgorod 88000, Ukraine. Translated from Khimiya
Geterotsiklicheskikh Soedinenii, No. 8, pp. 1255-1262, August, 2003. Original article submitted February 27,
2001.
0009-3122/03/3908-1099$25.00©2003 Plenum Publishing Corporation
1099

O
O
NH
SK
BrCH2C CH
NH
N
1
N
SCH2C CH
H2SO4
2
X2
EtONa
O
N
O
N
O
N
CH2
.
S
N
N
HXn
N
S
S
7
H2C
XHC
3a,b
8
MeCOONa
O
O
O
5a
5a
9a
Me
5
5
6
4 N
6
N4
7
N
3
2
7
8
8
10
9
9
1
S
3a
9a
10a
N
N
3 S
N
S
1
2
6
XHC
Me
4a,b
5
3, 4 a X = Br, b X = I; 3 a n = 3, b n = 5
deprotonates the N(3) atoms, so the intermediate 8 in this case has an angular structure. For heterocyclization
occurring on treatment with halogens, a synchronous donor–acceptor mechanism can be suggested according to
which the most nucleophilic atom N(1) participates in the cyclization, while the hydrogen halide molecule is
separated only in the last step of the process and so cannot affect the direction of the reaction.
Heterocyclization of quinazolinone 9, in contrast to compound 2, could be carried out only by treatment
with halogens.
O
N
H
X2
N
C
S
2
3a
,b
CH2
HC
X
X
Sodium ethoxide cleaves this substrate to form compound 1, while conc. H2SO4 results in tar formation.
An attempt to use a mixture of sulfuric and acetic acids as the cyclization agent likewise did not lead to the
target thiazoloquinazolinone. In this case, 2-(4-acetoxy-2-butynylthio)-4(1H)-quinazolinone is formed as the
major reaction product.
1100

O
N
O
N
O
N
N
N
X2
NH
MeCOONa
.
S
HXn
SCH2C C–CH2OH
S
9
X–C–CH2OH
11a,b
X–C–CH2OH
10a,b
10, 11 a X = Br, b X = I; 10 a n = 3, b n = 5
The composition and structure of all the synthesized compounds were confirmed by elemental analysis,
13
1H NMR and IR spectra, while the structure of compounds 4a,b, 5, 6, 11b was also confirmed by C NMR
spectra (Tables 1-3).
We should note that the positions of the absorption bands for the stretching vibrations of the (C=O)
bond of the carbonyl group in the IR spectra are quite different for thiazoloquinazolinones with linear and
angular structures. Thus in the IR spectra of linear derivatives, this band is located in the interval
1695-1670 cm-1, while for angular derivatives it is located in the 1665-1640 cm-1 region [2, 3]. This fact was
used to identify the synthesized compounds. Furthermore, the structure of compound 11b was confirmed by
X-ray diffraction (Fig. 1, Table 4).
The tricyclic system S(1)N(1)N(2)C(1-10) is considerably non-planar (deviations of atoms from the
mean-square plane are as high as 0.45 Å). The central six-membered heterocycle N(1)N(2)C(1)C(2)C(3)C(8) is
planar or approximately planar (the corresponding atoms deviate from the mean-square plane by 0.05-0.11 Å)
and is slightly distorted toward a twist–boat conformation (modified Cremer–Pople parameters [4] S, ψ, and θ
TABLE 1. Characteristics of Synthesized Compounds
Found, %
——————
Com-
pound
Empirical
formula
mp, °C
Calculated, %
С
Н
Hal
—
N
S
C11H8N2OS
60.52
61.09
3.65
3.73
12.90
12.95
14.69
14.83
219-220
189-193
173-176
184-186
230-232
299-300
167-169
216-217
194-197
136-138
188-190
213-214
2
C11H8Br4N2OS
C11H8I6N2OS
C11H7BrN2OS
C11H7IN2OS
C11H8N2OS
24.51
1.40
58.10
59.64
5.17
5.81
3а
3b
4а
4b
5
24.66
1.50
5.23
5.98
13.40
13.51
0.79
0.82
75.90
2.79
2.87
3.20
3.28
77.88
44.74
2.37
27.12
27.07
9.49
10.84
44.76
2.39
9.49
10.86
38.41
38.61
2.00
2.06
37.01
8.09
8.19
9.27
9.37
37.09
61.09
3.67
—
—
—
12.92
14.79
61.09
3.73
12.95
14.83
C11H8N2OS
61.05
61.09
3.69
3.73
12.89
12.95
14.75
14.83
6
C12H10N2O2S
C12H10Br4N2O2S
C12H10I6N2O2S
C12H9BrN2O2S
C12H9IN2O2S
58.41
4.00
11.21
12.82
9
58.52
4.09
11.37
13.02
25.21
25.47
1.52
1.78
54.22
56.48
4.85
4.95
5.42
5.67
10а
10b
11а
11b
14.10
0.89
73.21
2.65
3.01
14.30
1.00
75.56
2.78
3.18
44.17
44.32
2.54
2.79
24.39
24.57
8.42
8.61
9.59
9.86
38.59
2.30
34.05
7.46
8.43
38.73
2.44
34.10
7.53
8.62
1101

Fig. 1. General form of molecule 11b with numbering of the atoms. Hydrogen atoms are not shown.
are respectively 0.26, 2.2°, and 79.3°). The benzene ring C(3-8) forms a dihedral angle of 9.4° with this ring.
The five-membered heterocycle S(1)N(2)C(1)C(9)C(10) has an envelope conformation: the S(1), N(2), C(1),
and C(10) atoms are coplanar within 0.05 Å, while the C(9) atom deviates from this plane by 0.52 Å (the
dihedral angle between the S(1)N(2)C(1)C(10) and S(1)C(9)C(10) planes is 30.9°). The "base" of this envelope
TABLE 2. Spectral Data for Compounds Obtained
IR spectrum,
Com-
pound
1H NMR spectrum, δ, ppm (J, Hz)
ν(C=O), cm-1
1680
2
3.21 (1Н, t, J = 3.0, –С≡СН); 4.10 (2Н, d, J = 3.0, СН2); 7.45 (1Н, m,
ArH); 7.56 (1H, m, ArH); 7.78 (1H, m, ArH); 8.05 (1H, m, ArH);
12.65 (1H, br. s, NH)
4.37 (2Н, br. s, CH2); 7.30 (1Н, br. s, СНBr); 7.53 (1Н, m, ArH);
1715
1710
1655
1650
1640
1695
1685
3а
3b
4а
4b
5
7.81 (1H, m, ArH); 7.94 (1H, m, ArH); 8.07 (1H, m, ArH)
4.33 (2Н, br. s, CH2); 7.20 (1Н, br. s, СНI); 7.52 (1Н, m, ArH);
7.80 (1H, m, ArH); 7.92 (1H, m, ArH); 8.06 (1H, m, ArH)
4.35 (2Н, br. s, CH2); 7.28 (1Н, br. s, СНBr); 7.51 (1Н, m, ArH);
7.78 (1H, m, ArH); 7.92 (1H, m, ArH); 8.05 (1H, m, ArH)
4.32 (2Н, br. s, CH2); 7.17 (1Н, br. s, СНI); 7.50 (1Н, m, ArH);
7.77 (1H, m, ArH); 7.89 (1H, m, ArH); 8.05 (1H, m, ArH)
2.84 (3Н, s, CH3); 7.01 (1Н, s, S–СН); 7.61 (1Н, m, ArH);
7.79 (1H, m, ArH); 8.25 (2H, m, ArH)
2.80 (3Н, s, CH3); 6.85 (1Н, s, S–СН); 7.43 (1Н, m, ArH);
6
7.54 (1H, m, ArH); 7.80 (1H, m, ArH); 8.15 (1H, m, ArH)
4.07 (2Н, br. s, CH2OH); 4.16 (2Н, s, S–CH2); 5.17 (1Н, t, J = 6.0, OH);
7.49 (2H, m, ArH); 7.77 (1H, m, ArH); 8.05 (1H, m, ArH);
12.61 (1H, br. s, NH)
9
3.89 (d) and 4.05 (d) (2Н, J = 14, CH2–OH); 4.41 (d) and 4.51 (d)
(2H, J = 13, S–CH2); 7.44 (2H, m, ArH); 7.76 (1H, m, ArH);
7.99 (1H, m, ArH)
3.70 (d) and 3.93 (d) (2Н, J = 14, CH2–OH); 4.39 (d) and 4.55 (d)
(2H, J = 12.5, S–CH2); 7.30 (1H, m, ArH); 7.46 (1H, m, ArH);
7.76 (1H, m, ArH); 7.99 (1H, m, ArH)
3.88 (d) and 4.04 (d) (2Н, J = 14, CH2–OH); 4.39 (d) and 4.50 (d)
(2H, J = 13, S–CH2); 5.44 (1Н, s, ОН); 7.43 (2H, m, ArH);
7.75 (1H, m, ArH); 7.98 (1H, m, ArH)
3.71 (d) and 3.94 (d) (2Н, J = 14, CH2–OH); 4.37 (d) and 4.54 (d)
(2H, J = 13, S–CH2); 5.42 (1Н, t, J = 5, OH); 7.29 (1H, m, ArH);
7.45 (1H, m, ArH); 7.74 (1H, m, ArH); 7.98 (1H, m, ArH)
1710
1710
1655
1660
10а
10b
11а
11b
1102

TABLE 3. 13C NMR Spectra of Thiazoloquinazolinone Derivatives
Chemical shifts, δ, ppm
Com-
pound
С(1)
С(2)
С(3)
С(3а)
С(5)
С(5а)
137.28
141.63
135.88
—
31.64
30.68
105.67
104.81
39.94
—
—
—
134.54
—
165.37
161.64
163.96
—
168.14
162.17
167.85
160.27
168.46
118.06
122.90
118.89
117.44
117.86
4а
4b
5
6
134.40
165.99
11b
Chemical shifts, δ, ppm
Com-
pound
С(6, 7, 8, 9)
С(9а)
С-10а
–С–Х
–СН2ОН
–СН3
133.91, 127.92,
126.18, 116.48
138.21
148.56
138.21
147.47
138.64
—
97.88
—
—
—
4а
4b
5
137.91, 134.82,
—
—
91.91
—
—
19.29
17.99
—
127.20, 115.37
132.98, 128.17,
126.97, 116.84
—
134.60, 126.48,
159.84
—
—
—
6
125.26, 124.77
133.11, 127.22,
125.42, 116.72
100.05
64.77
11b
TABLE 4. Major Bond Lengths (d) and Bond Angles (ω) in the Molecule of
Compound 11b
Bond
d, Å
Angle
ω, deg.
I(1)–C(11)
S(1)–C(1)
S(1)–C(9)
O(1)–C(2)
O(2)–C(12)
N(1)–C(1)
N(1)–C(2)
N(2)–C(1)
N(2)–C(8)
N(2)–C(10)
C(2)–C(3)
C(3)–C(8)
2.092(7)
1.737(7)
1.819(9)
1.22(1)
1.39(1)
1.29(1)
C(1)–S(1)–C(9)
C(1)–N(1)–C(2)
C(1)–N(2)–C(8)
C(1)–N(2)–C(10)
C(8)–N(2)–C(10)
S(1)–C(1)–N(1)
S(1)–C(1)–N(2)
N(1)–C(1)–N(2)
N(1)–C(2)–C(3)
C(2)–C(3)–C(8)
N(2)–C(8)–C(3)
S(1)–C(9)–C(10)
91.9(4)
117.8(6)
119.1(6)
113.2(6)
126.7(6)
122.6(6)
111.8(5)
125.7(7)
117.6(7)
119.7(7)
116.5(7)
103.5(5)
1.40(1)
1.376(9)
1.395(9)
1.436(9)
1.483(12)
1.396(11)
S(1)N(2)C(1)C(10) forms a dihedral angle of 11.3° with the central 6-membered heterocycle. The N(2) atom has
a trigonal planar configuration of the bonds: the sum of the bond angles at this atom is 359.0(1.8)°. The
conjugation between the lone electron pair of the N(2) atom and the π-systems of the C(1)=N(1) double bond
and the benzene ring C(3-8) results in shortening of the N(2)–C(1) and N(2)–C(8) bonds to 1.376(9) and
1.395(8) Å compared with the standard value of 1.45 Å for N(sp2)–C(sp2) single bonds [5].
EXPERIMENTAL
1
The IR spectra were taken on a UR-10 in KBr disks; the H and 13C spectra were obtained on a
Varian-VXR (300 MHz) in DMSO-d6, internal standard TMS.
1103

TABLE 5. Coordinates of Atoms and Equivalent Isotropic Thermal
Parameters Ueq (Å2×103) in Structure 11b
Atom
x
y
z
Ueq
I(1)
S(1)
1.19963(7)
0.5712(3)
0.0600(9)
0.934(1)
0.19093(2)
0.20760(9)
0.0777(3)
0.1810(2)
0.1375(3)
0.1240(2)
0.1512(3)
0.0895(3)
0.0506(3)
-0.0042(3)
-0.0408(3)
-0.0234(3)
0.0300(3)
0.0685(3)
0.1850(3)
0.1534(3)
0.1565(3)
0.1377(3)
0.92273(7)
0.4123(3)
0.4760(11)
1.1761(8)
0.4446(8)
0.6459(8)
0.5050(9)
0.5232(11)
0.6412(11)
0.6914(11)
0.7917(12)
0.8432(12)
0.7975(11)
0.700(1)
0.0551
0.0595
0.0805
0.0636
0.0536
0.0469
0.0470
0.0543
0.0528
0.0585
0.0621
0.0588
0.0527
0.0497
0.0522
0.0458
0.0469
0.0522
O(1)
O(2)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
0.293(1)
0.6170(9)
0.4756(11)
0.2331(12)
0.3863(11)
0.3377(13)
0.4801(14)
0.6722(13)
0.7265(12)
0.5804(11)
0.8194(12)
0.8013(11)
0.9206(11)
0.8780(12)
0.5371(11)
0.699(1)
0.870(1)
1.043(1)
X-ray Diffraction Study of a Single Crystal of Compound 11b with linear dimensions 0.25 × 0.35 ×
0.45 mm was done at room temperature on an Enraf-Nonius CAD-4 automatic four-circle diffractometer (CuKα
≤
≤ 9, 0 ≤ ≤ 26, -9 ≤ ≤ 9). We collected
k l
radiation, scanning rate ratio ω/2θ = 1.2, θmax = 60°, hkl range 0
h
2043 reflections total, of which 1821 are symmetrically independent (R factor used for averaging, 0.044). The
crystals of compound 11b are monoclinic, a = 7.292(2), b = 22.975(3), c = 7.760(1) Å, β = 109.59(2)°,
V = 1224.8 Å3, M = 372.18, Z = 4, dcalc = 2.02 g/cm3, µ = 223.16 cm-1, space group P21/c. The structure was
deciphered by the direct method and least-squares refined in the full-matrix anisotropic approximation using the
CRYSTALS software package [6]. In the refinement, we used 1589 reflections with I > 3σ(I) (163 refined
parameters, the number of reflections divided by the parameter 9.7). The hydrogen atoms were located
geometrically and included in the calculation with fixed positions and thermal parameters. In the refinement, we
used the Chebyshev weighting scheme [7] with parameters 6.12, -2.94, 2.74, -2.03, and -1.39. The final values
of the R factors were R = 0.057 and Rw = 0.063, GOOF = 1.095. The residual electron density from a Fourier
difference series was 0.65 and -1.29 e/Å3. The atomic coordinates are given in Table 5. The full set of
crystallographic data for structure 11b has been deposited in the Cambridge Structural Database
(Reg. No. CCDC 155073).
2-(2-Propynylthio)-4(1H)-quinazoline (2). An 80% solution of propargyl bromide in toluene (6.1 ml)
was added to a solution of (10.8 g, 50 mmol) of 2-mercapto-4(1H)-quinazolinone potassium salt 1 in a mixture
of ethanol (65 ml) and water (15 ml). The reaction mixture was refluxed on a water bath for 45 min. The
crystalline precipitate was filtered out after cooling, washed with water and then alcohol, and dried. It was
recrystallized from a 4:1 ethanol–DMF mixture. Yield of quinazolinone 2: 9.07 g (84%).
2-(4-Hydroxy-2-butynylthio)-4(1H)-quinazolinone (9) was obtained from the potassium salt 1 and
1-chloro-2-butyn-4-ol as for compound 2 and recrystallized from a 1:1 ethanol–dioxane mixture. Yield 79%.
a
1-Bromomethylidene-1,2-dihydro-5H-thiazolo[3,2- ]quinazolin-5-onium Tribromide (3a).
Compound 2 (0.432 g, 2 mmol) were dissolved in glacial acetic acid (70 ml) at a temperature of 50-60°C. A
solution of bromine (0.21 m, 4 mmol) in glacial acetic acid (15 ml) was added dropwise with stirring to the
solution obtained, at a temperature of 18-20°C. The mixture was stirred for another 2 h and allowed to stand for
1104

12 h to crystallize. The fine crystalline precipitate of the orange salt 3a was washed on the filter with acetic acid
and then ether, and then was dried. Yield 0.98 g (92%).
a
A solution
1-Iodomethylidene-1,2-dihydro-5H-thiazolo[3,2- ]quinazolin-5-onium Pentaiodide (3b).
of iodine (1.52 g, 6 mmol) in CH3COOH (110 ml) was added with stirring to a solution of compound 2 (0.432 g,
2 mmol) in glacial acetic acid (70 ml) at 18-20°C. After 24 hours, a fine crystalline brown precipitate was
formed, which was filtered out, washed with alcohol and then ether, and then dried. Yield of salt 3b: 1.85 g
(95%).
a
1-Bromomethylidene- and 1-Iodomethylidene-1,2-dihydro-5H-thiazolo[3,2- ]quinazolin-5-one
(4a) and (4b). An 20% aqueous solution of sodium acetate (20-25 ml) was added to a solution of the
corresponding salt 3a or 3b (2 mmol) in DMSO (15-20 ml), stirred, and allowed to stand for 2 h. The fine
crystalline white precipitate formed was filtered out, washed with water, then alcohol, and then ether, and then
dried. Quinazolinones 4a and 4b were recrystallized respectively from ethanol and a 1:1 ethanol–dioxane
mixture. Yield of compound 4a: 0.38 g (65%). Yield of compound 4b: 0.48 g (70%).
a
1-Methyl-5H-thiazolo[3,2- ]quinazolin-5-one (5).
2
Compound (0.432 g, 2 mmol) was added to a 7%
solution of sodium ethoxide in ethanol (8 ml) at 10-15°C. The mixture was carefully stirred until the precipitate
completely dissolved, and the solution was allowed to stand at 18-20°C. After 24 hours, the crystalline
precipitate was filtered out, washed with water, and dried. It was recrystallized from a 1:1 ethanol–DMF
mixture. Yield of compound 5: 0.35 g (80%).
b
3-Methyl-5H-thiazolo[2,3- ]quinazolin-5-one (6).
2
Compound (0.432 g, 2 mmol) were dissolved in
conc. H2SO4 (5 ml) at 0°C. The solution was allowed to stand at 18-20°C for 12 h, and then was poured into
water (50 ml) cooled down to 0°C. After 12 h, the fine crystalline precipitate of quinazolinone 6 formed was
filtered out, washed with water, and dried. It was recrystallized from a 1:1 ethanol–dioxane mixture. Yield of
compound 6: 0.32 g (75%).
a
1-(1-Bromo-2-hydroxyethylidene)-1,2-dihydro-5H-thiazolo[3,2- ]quinazolin-5-onium Tribromide
(10a). A solution of bromine (0.21 ml, 4 mmol) in CH3COOH (25 ml) was added dropwise with continuous
stirring over a 2 h period to a suspension of compound 9 (0.49 g, 2 mmol) in glacial acetic acid (50 ml), after
which stirring was continued for another 2 h. After 15 h, the fine crystalline red-orange material formed was
separated by filtration, washed with ether, and dried in air. Yield of salt 10a: 1.04 g (92%).
a
1-(2-Hydroxy-1-iodoethylidene)-1,2-dihydro-5H-thiazolo[3,2- ]quinazolin-5-onium Pentaiodide
(10b). Iodine (1.52 g, 6 mmol) in CH3COOH (140 ml) was added dropwise with continuous stirring over a 3 h
period to a suspension of compound 9 (0.49 g, 2 mmol) in glacial acetic acid (60 ml). Stirring was continued for
another 2 h. After 30 h, the fine crystalline black precipitate formed of salt 10b was separated by filtration,
washed with ether, and dried in air. Yield of salt 10b: 1.80 g (90%).
Bases 11a and 11b. An 20% aqueous solution of sodium acetate (15-20 ml) were added to a solution of
salt 10a or 10b (2 mmol) in DMSO (20 ml). The corresponding bases were crystallized from a solution over a
12-14 h period. In order to remove tarry impurities from the bases, they were ground with acetone (50-60 ml).
a
Yield 0.42 g
1-(1-Bromo-2-hydroxyethylidene)-1,2-dihydro-5H-thiazolo[3,2- ]quinazolin-5-one (11a).
(65%).
(72%).
a
Yield 0.54 g
1-(2-Hydroxy-1-iodoethylidene)-1,2-dihydro-5H-thiazolo[3,2- ]quinazolin-5-one (11b).
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1106