Condensed diazepines. Synthesis of 1-r-3,4-dihydro-5H-benzothieno[2,3-d][1, 2]diazepin-4-ones

Article abstract of DOI:10.1007/s10593-012-1146-4

Novel 1-R-3,4-dihydro-5H-benzothieno[2,3-d][1,2]diazepin-4-ones have been prepared by the cyclization of 2-acyl(aroyl)benzo[b]thiophene-3-acetic acids or 1-R-benzothieno[2,3-c]pyr-3-ones with hydrazine hydrate.

Full text of DOI:10.1007/s10593-012-1146-4

Chemistry of Heterocyclic Compounds, Vol. 48, No. 9, December, 2012 (Russian Original Vol. 48, No. 9, September, 2012)
CONDENSED DIAZEPINES. SYNTHESIS OF 1-R-3,4-DIHYDRO-
5H-BENZOTHIENO[2,3-d][1,2]DIAZEPIN-4-ONES
V. S. Tolkunov1*, A. B. Eres'ko1, A. V. Mazepa2, G. V. Palamarchuk3,
O. V. Shishkin3,4, and S. V. Tolkunov1
Novel 1-R-3,4-dihydro-5H-benzothieno[2,3-d][1,2]diazepin-4-ones have been prepared by the
cyclization of 2-acyl(aroyl)benzo[b]thiophene-3-acetic acids or 1-R-benzothieno[2,3-c]pyr-3-ones with
hydrazine hydrate.
Keywords: 2-acyl(aroyl)benzo[b]thiophene-3-acetic acids, 1-aryl-3,4-dihydro-5H-benzothieno[2,3-d]-
[1,2]diazepin-4-ones, hydrazine hydrate, cyclization.
1-Aryl-3,5-dihydro-4H-2,3-benzodiazepin-4-ones are actively studied in connection with their anti-
spasmodic activity [1-4]. They are also of interest as starting materials in the synthesis of condensed triazolo-
and tetrazolo-2,3-benzodiazepines [5-9].
Known routes for preparing 2,3-benzodiazepin-4-ones are based on the reaction of hydrazine with
2-aroyl(acetyl)-4,5-dimethoxyphenylacetic acids or their esters [10, 11]. Amongst heterocyclic analogs of
2,3-benzodiazepin-4-ones there are known only 3H-[1,2]diazepino[5,6-b]indoles and the 2,3-dihydro-2-oxo-
1H-[1,2]diazepino[4,5-b]indoles and 1-aryl-3,4-dihydro-5H-benzofuro[2,3-d][1,2]diazepin-4-ones obtained by
us [12-14].
In continuing our work on the synthesis of hetero analogs of 2,3-benzodiazepin-4-ones, we have studied
the cyclization of 2-acyl(aroyl)benzo[b]thiophene-3-acetic acids, their methyl esters, and amides using
hydrazine hydrate.
Under the same experimental conditions the reaction occurs differently for the 2-acetyl- (1a) and 2-pro-
pionyl-5-methylbenzo[b]thiophene-3-acetic acid (1b) with hydrazine hydrate in alcohol or the sodium salts of
these acids in water with subsequent acidification by acetic acid. Acid 1a gives the hydrazone 2, while the
reaction of acid 1b with hydrazine leads to the azine 3. Moreover, heating hydrazone 2 in acetic acid does not
_______
*To whom correspondence should be addressed, e-mail: s_tolkunov@yahoo.com.
1L. M. Litvinenko Institute of Physico Organic Chemistry and Coal Chemistry, Ukraine National Academy of
Sciences, 70 R. Luxemburg St., Donetsk 83114, Ukraine.
2A. V. Bogatsky Physico-Chemical Institute, Ukraine National Academy of Sciences, 86 Lyustdorfskaya Road,
Odessa 65080, Ukraine; e-mail: almazepa@rambler.ru.
3Scientific-Technological Complex "Institute of Monocrystals", Ukraine National Academy of Sciences, 60
Lenin Ave., Kharkiv 61001, Ukraine; e-mail: shishkin@xray.isc.kharkov.com.
4V. N. Karazin National University, 4 Freedom Sq., Kharkiv 61077, Ukraine; e-mail: shishkin@xray.isc.kharkov.com.
_________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1471-1482, September, 2012.
Original article submitted January 6, 2012.
0009-3122/12/4809-1371©2012 Springer Science+Business Media New York
1371

give the corresponding azine (as observed for benzo[b]furan and indole hydrazones having a similar structure
[13, 15]). In the presence of dicyclohexylcarbodiimide (DCC), the hydrazone 2 cyclizes to 2-amino-1,6-di-
methylbenzothieno[2,3-c]pyridin-3-one (4a).
COOH 1) NaHCO3, H2O
COOH
N
2) N2H4, , 1 h
(R = Et)
Me
Me
O
S
1a,b
R
S
Et
2
(R = Me)
3
O
COOH
N
DCC, CH2Cl2
room temp., 5 h
Me
NH2
NH2
N
Me
S
2
Me
Me
S
4a
1 a R = Me, b R = Et
The cyclization of 2-acetyl-5-methylbenzo[b]thiophene-3-acetic acid phenylhydrazone (5) occurs
similarly, in this case forming the 1,6-dimethyl-2-phenylaminobenzothieno[2,3-c]pyridin-3-one (6).
O
COOH
H
PhNHNH2
H
DCC, CH2Cl2
room temp., 5 h
N
N
Me
Me
N
N
2-PrOH, , 1 h
Ph
1a
Ph
Me
S
S
Me
5
6
The 6-R-1-methylbenzothieno[2,3-c]pyr-3-ones 7a,b, 3-acetylamino-1,6-dimethylbenzothieno-
[2,3-c]pyrilium tetrafluoroborate (8), and 5-R-2-acetylbenzo[b]thiophene-3-acetic acid esters 9a,b react with
hydrazine acetate in 2-propanol to form the 2-amino derivatives 4a,b.
O
NHAc
O+
NH2NH2·AcOH
2-PrOH, , 5 h
NH2
N
Me
–
BF4
Me
Me
S
S
8
4b
O
COOMe
NH2NH2·AcOH
2-PrOH, , 5 h
R
O
O
R
or
4a,b
S
9a,b
Me
Me
S
7a,b
7, 9 a R = H, b R = Me
Treatment of 1-ethyl-6-methylbenzothieno[2,3-c]pyr-3-one (7c) with hydrazine acetate in 2-propanol
unexpectedly gave the 1-ethyl-7-methylbenzothieno[2,3-d][1,2]diazepin-4-one (10).
1372

TABLE 1. Physicochemical Characteristics of the Compounds Synthesized
Found, %
Com-
pound
Empirical
formula
Yield, %
(method)
Calculated, %
Mp, °С
С
H
4
N
5
S
6
1
2
3
7
8
C13H12O3S
62.76
62.88
64.24
64.10
59.41
59.52
64.69
64.59
4.75
4.84
5.44
5.38
5.45
5.38
5.50
5.42
—
—
13.01
12.91
12.34
12.22
12.31
12.22
12.39
12.32
173-174
94
95
83
90
1a
1b
2
C14H14O3S
C13H14N2O2S
C28H28N2O4S2
C13H12N2OS
10.59
10.68
5.47
5.38
11.35
11.47
150-151
179-180
260-261
3
64.03
63.91
5.02
4.95
13.21
13.12
67 (А)
74 (B)
72 (C)
62 (D)
4a
C12H10N2OS
C19H18N2O2S
62.72
62.59
4.31
4.38
12.22
12.16
13.83
13.92
252-253
186-187
63 (А)
74 (B)
72 (C)
4b
5
67.52
67.43
5.28
5.36
8.15
8.28
9.39
9.47
75
C19H16N2OS
C12H8O2S
71.10
71.22
66.53
66.65
68.70
68.83
48.65
48.72
62.73
62.88
63.97
64.10
65.21
65.09
62.39
62.25
61.49
61.61
68.45
68.35
65.48
65.37
73.45
73.36
73.82
73.95
70.01
70.11
67.31
67.44
63.22
63.36
69.02
68.90
69.80
69.66
66.13
66.24
64.15
64.03
59.46
59.58
70.47
70.35
66.92
67.04
5.10
5.03
3.65
3.73
4.90
4.95
3.43
3.50
4.81
4.87
5.43
5.38
5.40
5.46
6.70
6.62
6.48
6.39
5.94
6.02
5.82
5.76
3.54
3.62
4.19
4.14
3.99
3.92
4.25
4.17
2.79
2.84
4.13
4.08
4.60
4.55
4.39
4.32
4.59
4.53
3.39
3.33
4.92
4.97
4.79
4.74
8.82
8.74
—
9.93
234-235
206-207
118-120
200-201
118-120
105-106
189-190
131-132
124-125
216-217
190-192
216-217
205-207
204-205
203-204
170-172
149-150
158-159
151-152
174-175
184-185
194-195
164-165
63
92
93
48
78
85
64
73
75
84
82
65
70
72
85
54
55
77
82
88
85
94
82
6
10.01
14.43
14.83
13.19
13.12
9.21
9.29
12.84
12.91
12.29
12.22
12.33
12.41
11.14
11.08
9.58
9.67
9.18
9.12
8.83
8.73
11.64
11.52
11.08
10.97
10.31
10.40
9.60
9.48
22.66
22.55
10.94
10.82
7a
C14H12O2S
C14H12BF4NO2S
C13H12O3S
C14H14O3S
C14H14N2OS
C15H19N3OS
C17H21N3O2S
C20H21N3OS
C20H21N3O2S
C17H10O2S
C18H12O2S
C18H12O3S
C19H14O4S
C15H8O2S2
C17H12O3S
C18H14O3S
C18H14O4S
C19H16O5S
C15H10O3S2
C19H16O3S
C19H16O4S
—
7c
4.11
4.06
—
8
9a
—
9b
10.92
10.84
14.43
14.52
12.54
12.68
11.83
11.96
10
11a
11b
12a
12b
13a
13b
13c
13d
13e
14a
14b
14c
14d
14e
14f
14g
11.32
11.43
—
—
—
—
—
—
—
—
—
10.25
10.33
9.93
9.82
9.11
9.00
21.32
21.21
9.98
9.88
9.54
9.42
—
—
—
1373

TABLE 1 (continued)
1
2
C17H12N2OS
C18H14N2OS
3
4
5
6
7
8
69.72
69.84
70.69
70.56
4.20
4.14
4.56
4.61
9.48
9.58
9.22
9.14
11.08
10.97
10.56
10.47
236-237
222-224
52 (A)
47 (B)
40 (A)
84 (B)
48 (C)
15a
15b
67.18
67.06
64.68
64.76
60.26
60.38
71.33
71.22
67.72
67.84
70.47
70.35
70.87
70.98
67.65
67.78
4.45
4.38
4.51
4.58
3.42
3.38
5.10
5.03
4.84
4.79
5.04
4.97
5.42
5.36
5.07
5.12
8.60
8.69
8.02
7.95
9.48
9.39
8.66
8.74
10.02
9.95
9.18
9.10
21.60
21.49
10.09
10.01
9.65
9.53
9.98
9.88
9.59
9.47
9.13
9.05
198-200
203-205
182-183
269-270
218-220
121-122
136-137
116-117
46 (A)
84 (B)
44 (A)
45 (B)
56 (А)
48 (B)
51 (B)
32 (В)
33 (B)
37 (C)
68
72
69
15c
15d
15e
15f
C18H14N2O2S
C19H16N2O3S
C15H10N2OS2
C19H16N2OS
C19H16N2O2S
C19H16O3S
15g
16a
16b
16c
8.41
8.33
—
—
—
C20H18O3S
C20H18O4S
O
O
NH2NH2·AcOH
NH
2-PrOH
O
Me
Me
N
Et
S
7c
S
10
Et
The structure of diazepinone 10 was proved by X-ray structural analysis (Fig. 1).
Fig. 1. Molecular structure of compound 10 with atoms represented by thermal vibration ellipsoids of 50%
probability.
The diazepine ring has a "boat" conformation. The atoms C(10), N(1), and N(2) deviated from the mean
square plane of the remaining ring atoms by 0.68, 1.45, and 1.18 Å, respectively. The ethyl group is coplanar
with the C(11)–C(12) bond (dihedral angle C(14)–C(13)–C(11)–C(12) is -178.3(3)º). The molecules in the
compound 10 crystal form chains along the (0 0 1) crystallographic direction as a result of the intermolecular
hydrogen bonds N(2)–H(2B)···O(1)' (0.5+x, -0.5+y, -0.5+z): H···O 2.06 Å, N–H···O 172º).
1374

The 2-acetylbenzo[b]thiophen-3-acetic acid dimethylamide and morpholide [16], and the 2-acetyl-
benzo[b]thiophene-3-acetic acid arylamides [15] react with hydrazine hydrate in alcohol under prolonged reflux
to give only the corresponding hydrazones 11a,b and 12a,b. Hydrazinolysis of the amide groups in alcohol does
not occur. Subsequent heating of hydrazones 11a,b and 12a,b in acetic or trifluoroacetic acid gives the 2-amino
derivative 4a.
R2
R2
R1
R1
N
N
NH2NH2·H2O
EtOH, , 16 h
TFA or AcOH
, 1 h
O
N
O
O
4a
Me
Me
NH2
S
11a,b, 12a,b
S
Me
Me
11 a R1 = R2 = Me; b R1+R2 = (CH2CH2)2O; 12 а R1 = H, R2 = 4-MeC6H4; b R1 = H, R2 = 4-MeOC6H4
The 1-aryl benzothieno[2,3-c]pyr-3-ones 13a-e, prepared by acylation of benzo[b]thiophene-3-acetic acid
esters using benzoic acids in PPA, are internal esters of the 2-aroylbenzo[b]thiophene-3-acetic acids 14a-e.
They can be used in the synthesis of diazepines analogously to benzofuran derivatives [14].
O
COOH
O
1) NaOH, H2O
2) H+
R
O
R
R1COOH
PPA
100°C
1.5 h
R1
R1
S
S
14a–g
13a–e
COOMe
COOMe
O
1) NaOH, H2O
2) H+
R1COCl, SnCl4
CH2Cl2, 25–30°C, 3 h
R
R
R1
S
S
16a–c
O
N2H4·H2O
Ethyl cellosolve, , 20 h
NH
N
13a–e, 14a–g, 16a–c
R
R1
S
15a–g
13–15 а–е R = H, a R1 = Ph, b R1 = 4-MeC6H4, c R1 = 4-MeOC6H4, d R1 = 3,4-(MeO)2C6H3,
е R1 = 2-thienyl; f,g R = Me, f R1 = 4-MeC6H4, g R1 = 3-MeOC6H4;
16 a R = H, R1 = 4-MeC6H4; b R = Me, R1 = 4-MeC6H4; c R = Me, R1 = 3-MeOC6H4
Conversion of the 1-arylbenzothieno[2,3-c]pyrones 13a-e to the corresponding 1-aryl-3,4-dihydro-
5H benzothieno[2,3-d][1,2]diazepin-4-ones 15a-e occurs upon prolonged refluxing with a fivefold excess of
hydrazine hydrate in ethyl cellosolve in the presence of catalytic amounts of acetic acid (method A). The
benzothieno[2,3-d][1,2]diazepin-4-ones 15a-g can also be prepared under analogous conditions by cyclization
of the 2-aroylbenzo[b]thiophene-3-acetic acids 14a-g (method B) or their esters 16a-c (method C). The yields of
the diazepines 15a-g are similar when using the different methods.
1375

TABLE 2. 1H NMR Spectra of the Compounds Synthesized
Com-
pound
Chemical shifts, δ, ppm (J, Hz)
1
2
2.51 (3Н, s, 5-СН3); 2.60 (3Н, s, COСН3); 4.18 (2Н, s, СH2СООH);
7.34 (1H, d, J = 8.0, H-6); 7.70 (1Н, s, Н-4); 7.78 (1Н, d, J = 8.0, H-7);
12.28 (1H, s, СООH)
1a
1.18 (3Н, t, J = 7.2, CH2CН3); 2.50 (3Н, s, 5-СН3); 2.95 (2Н, q, J = 7.2, CH2СН3);
4.17 (2Н, s, СH2СООH); 7.32 (1H, d, J = 8.0, H-6); 7.68 (1Н, s, Н-4);
7.76 (1Н, d, J = 8.0, H-7); 12.25 (1H, s, СООH)
1b
2.21 (3Н, s, СН3C=N); 2.49 (3Н, s, 5-СН3); 3.89 (2Н, s, СH2СООH); 6.65 (2Н, s, NH2);
7.13 (1H, d, J = 8.0, H-6); 7.50 (1Н, s, Н-4); 7.64 (1Н, d, J = 8.0, H-7); 12.85 (1H, s, СООH)
2
3
1.22 (3Н, t, J = 7.2, CH2CН3); 2.51 (3Н, s, 5-СН3); 3.00 (2Н, q, J = 7.2, CH2СН3);
4.22 (2Н, s, СH2СООH); 7.23 (1H, d, J = 8.0, H-6); 7.59 (1Н, s, Н-4);
7.73 (1Н, d, J = 8.0, H-7); 12.25 (1H, s, СООH)
2.46 (3Н, s, 6-СН3); 2.63 (3Н, s, 1-СН3); 6.45 (2Н, s, NH2); 7.09 (1Н, s, Н-4);
7.37 (1Н, d, J = 8.0, Н-7); 7.71 (1Н, d, J = 8.0, Н-8); 7.98 (1Н, s, Н-5)
4a
4b
5
2.62 (3Н, s, 1-СН3); 6.43 (2Н, s, NН2); 7.21 (1Н, s, Н-4); 7.44 (1Н, t, J = 8.0, Н-7);
7.56 (1Н, t, J = 8.0, Н-6); 7.90 (1Н, d, J = 8.0, Н-8); 8.21 (1Н, d, J = 8.0, Н-5)
2.40 (3Н, s, СН3C=N); 2.50 (3Н, s, 5-СН3); 4.11 (2Н, s, СН2СООН);
6.76 (1Н, t, J = 8.0, Н-4'); 7.14 (1Н, d, J = 8.0, Н-6); 7.19-7.25 (4Н, m, Н-2',3',5',6');
7.48 (1Н, s, Н-4); 7.65 (1Н, d, J = 8.0, H-7); 9.27 (1Н, s, NH); 12.24 (1Н, s, СООН)
2.58 (3Н, s, 6-СН3); 2.65 (3Н, s, 1-СН3); 6.62 (2Н, d, J = 8.0, H-2',6');
6.84 (1Н, t, J = 8.0, H-4'); 7.17 (2Н, t, J = 8.0, H-3',5'); 7.24 (1Н, s, H-4);
7.47 (1Н, d, J = 8.0, H-7); 7.96 (1Н, d, J = 8.0, H-8); 8.09 (1Н, s, H-5); 9.04 (1Н, s, NH)
6
2.40 (3Н, s, 1-СН3); 6.86 (1Н, s, Н-4); 7.39 (1Н, t, J = 8.0, Н-7);
7.59 (1Н, t, J = 8.0, Н-6); 7.77 (1Н, d, J = 8.0, Н-8); 8.16 (1Н, d, J = 8.0, Н-5)
7a
7c
8*
1.38 (3Н, t, J = 7.2, CH2CН3); 2.47 (3Н, s, 5-СН3); 2.71 (2Н, q, J = 7.2, CH2СН3);
6.71 (1Н, s, Н-4); 7.39 (1H, d, J = 8.0, H-7); 7.58 (1Н, d, J = 8.0, H-8); 7.88 (1Н, s, Н-5)
2.51 (3Н, s, NHCOCН3); 3.13 (3Н, s, 1-СН3); 7.78 (1Н, t, J = 8.0, H-7);
8.01 (1Н, t, J = 8.0, H-6); 8.06 (1H, d, J = 8.0, Н-8); 8.57 (1Н, d, J = 8.0, Н-5);
9.02 (1Н, s, Н-4); 10.55 (1Н, s, NHCO)
2.62 (3Н, s, СН3C=O); 3.67 (3Н, s, OСН3); 4.29 (2Н, s, СH2); 7.46 (1Н, t, J = 8.0, Н-6);
7.52 (1Н, t, J = 8.0, Н-5); 7.91 (2Н, d, J = 8.0, Н-4,7)
9a
9b
10
2.51 (3Н, s, 5-СН3); 2.60 (3Н, s, СН3C=O); 3.65 (3Н, s, OСН3); 4.18 (2Н, s, СH2);
7.34 (1H, d, J = 8.0, H-6); 7.70 (1Н, s, Н-4); 7.78 (1Н, d, J = 8.0, H-7)
1.26 (3Н, t, J = 7.2, CН3CH2); 2.53 (3Н, s, 7-СН3); 2.78 (2Н, q, J = 7.2, СН3CH2);
3.56 (2Н, s, СH2); 7.26 (1H, d, J = 8.0, H-8); 7.72 (1Н, s, Н-6); 7.73 (1Н, d, J = 8.0, H-9);
10.71 (1Н, s, NH)
2.13 (3Н, s, СН3C=N); 2.45 (3Н, s, 5-СН3); 2.85 (3Н, s) и 3.02 (3Н, s, N(CH3)2);
4.02 (2Н, s, СН2); 6.36 (2Н, s, NH2); 6.95 (1Н, d, J = 8.0, Н-6); 7.17 (1Н, s, Н-4); 7.40
(1Н, d, J = 8.0, Н-7)
11a
11b
12a
2.06 (3Н, s, СН3C=N); 2.40 (3Н, s, 5-СН3); 3.36-3.52 (8Н, m, N(CH2CH2)2O);
4.01 (2Н, s, СН2); 6.77 (2Н, s, NH2); 7.02 (1Н, d, J = 8.0, Н-6); 7.31 (1Н, s, Н-4);
7.41 (1Н, d, J = 8.0, Н-7)
2.23 (3Н, s, СН3C=N); 2.24 (3Н, s, 4'-СН3); 2.49 (3Н, s, 5-СН3); 3.92 (2Н, s, СН2);
6.79 (2Н, s, NН2); 6.98 (2Н, d, J = 8.0, H-3',5'); 7.13 (1Н, d, J = 8.0, H-6);
7.40 (2Н, d, J = 8.0, H-2',6'); 7.63 (1Н, d, J = 8.0, H-7); 7.73 (1Н, s, H-4);
10.52 (1Н, s, NH)
2.25 (3Н, s, СН3C=N); 2.50 (3Н, s, 5-СН3); 3.71 (3Н, s, 4'-ОСН3); 3.91 (2Н, s, СН2);
6.74 (2Н, d, J = 8.0, H-3',5'); 6.79 (2Н, s, NН2); 7.13 (1Н, d, J = 8.0, H-6);
7.45 (2Н, d, J = 8.0, H-2',6'); 7.62 (1Н, d, J = 8.0, H-7); 7.75 (1Н, s, H-4);
10.45 (1Н, s, NH)
12b
7.06 (1Н, s, Н-4); 7.44 (1Н, t, J = 8.0, Н-7); 7.54 (1Н, t, J = 8.0, H-4');
7.60 (2Н, d, J = 8.0, H-3',5'); 7.62 (1H, t, J = 8.0, Н-6); 7.73 (1Н, d, J = 8.0, Н-8);
7.96 (2Н, d, J = 8.0, H-2',6'); 8.22 (1Н, d, J = 8.0, Н-5)
13a
13b
13c
2.45 (3Н, s, 4'-СН3); 7.05 (1Н, s, Н-4); 7.41 (2Н, d, J = 8.0, H-3',5');
7.44 (1Н, t, J = 8.0, Н-7); 7.62 (1H, t, J = 8.0, Н-6); 7.77 (1Н, d, J = 8.0, Н-8);
7.83 (2Н, d, J = 8.0, H-2',6'); 8.23 (1Н, d, J = 8.0, Н-5)
3.90 (3Н, s, 4'-ОСН3); 7.00 (1Н, s, Н-4); 7.14 (2Н, d, J = 8.0, H-3',5');
7.45 (1Н, t, J = 8.0, Н-7); 7.63 (1H, t, J = 8.0, Н-6); 7.79 (1Н, d, J = 8.0, Н-8);
7.90 (2Н, d, J = 8.0, H-2',6'); 8.24 (1Н, d, J = 8.0, Н-5)
1376

TABLE 2 (continued)
1
2
3.87 (3Н, s, 3'-ОСH3); 3.89 (3Н, s, 4'-ОСH3); 7.09 (1Н, s, Н-4); 7.19 (1H, d, J = 8.0, H-5');
7.35 (1H, s, H-6'); 7.39 (1H, s, H-2'); 7.51 (1H, t, J = 8.0, H-7); 7.65 (1H, t, J = 8.0, H-6);
7.87 (1Н, d, J = 8.0, Н-8); 8.29 (1Н, d, J = 8.0, Н-5)
13d
13e
6.96 (1Н, s, Н-4); 7.30 (1H, t, J = 4.0, H-4'); 7.44 (1H, t, J = 8.0, Н-7);
7.62 (1H, t, J = 8.0, Н-6); 7.73 (1H, d, J = 4.0, H-5'); 7.77 (1Н, d, J = 8.0, Н-8);
7.84 (1H, d, J = 4.0, H-3'); 8.19 (1Н, d, J = 8.0, Н-5)
4.06 (2Н, s, СН2); 7.48-7.66 (5H, m, H-5,6,3',4',5'); 7.84-7.97 (4H, m, H-4,7,2',6');
12.25 (1H, s, СООH)
14a
14b
2.44 (3Н, s, 4'-СH3); 4.03 (2Н, s, СН2); 7.29 (2H, d, J = 8.0, H-3',5');
7.43-7.50 (2H, m, H-5,6); 7.76 (2H, d, J = 8.0, H-2',6'); 7.87-7.91 (2H, m, H-4,7);
12.21 (1H, s, СООH)
3.87 (3Н, s, 4'-ОСH3); 3.98 (2Н, s, СН2); 6.98 (2H, d, J = 8.0, H-3',5');
7.42-7.49 (2H, m, H-5,6); 7.86 (2H, d, J = 8.0, H-2',6'); 7.87-7.90 (2H, m, H-4,7);
12.21 (1H, s, СООH)
14c
14d
14e
14f
3.83 (3Н, s, 3'-ОСH3); 3.87 (3Н, s, 4'-ОСH3); 4.00 (2Н, s, СН2);
7.01 (1H, d, J = 8.0, H-5'); 7.34 (1H, d, J = 8.0, H-6'); 7.39 (1H, s, H-2');
7.45-7.55 (2H, m, H-5,6); 7.87-7.99 (2H, m, H-4,7); 12.33 (1H, s, СООH)
3.00 (СООН in exchange with Н2О); 4.12 (2Н, s, СН2); 7.21 (1H, t, J = 4.0, H-4');
7.45-7.52 (2H, m, H-5,6); 7.86 (1H, d, J = 4.0, H-5'); 7.91 (1Н, d, J = 8.0, Н-7);
7.94 (1Н, d, J = 8.0, H-4); 8.00 (1H, d, J = 4.0, H-3')
2.45 (3Н, s, 4'-СH3); 2.51 (3Н, s, 5-СH3); 3.00 (СООН in exchange with Н2О);
4.00 (2Н, s, СН2); 7.28 (2H, d, J = 8.0, H-3',5'); 7.31 (1H, d, J = 8.0, H-6);
7.67 (1H, s, H-4); 7.75 (2H, d, J = 8.0, H-2',6'); 7.75 (1H, d, J = 8.0, H-7)
2.52 (3Н, s, 5-СH3); 3.85 (3Н, s, 3'-ОСH3); 4.02 (2Н, s, СН2); 7.15 (1H, d, J = 8.0, H-4');
7.32 (2H, m, H-2',6); 7.41 (2H, m, H-5',6'); 7.70 (1H, s, H-4); 7.78 (1H, d, J = 8.0, H-7);
12.22 (1H, s, СООH)
14g
15a
15b
15c
15d
3.75 (2Н, s, СН2); 7.42-7.47 (4H, m, H-8,3',4',5'); 7.49 (1H, t, J = 8.0, H-7);
7.78 (2H, d, J = 8.0, H-2',6'); 7.85 (1H, d, J = 8.0, H-9); 8.02 (1H, d, J = 8.0, H-6);
11.22 (1Н, s, NH)
2.41 (3Н, s, 4'-СH3); 3.73 (2Н, s, СН2); 7.21 (2H, d, J = 8.0, H-3',5');
7.45 (1H, t, J = 8.0, H-8); 7.49 (1H, t, J = 8.0, H-7); 7.66 (2H, d, J = 8.0, H-2',6');
7.85 (1H, t, J = 8.0, H-9); 8.01 (1H, d, J = 8.0, H-6); 11.12 (1Н, s, NH)
3.72 (2Н, s, СН2); 3.84 (3Н, s, 4'-ОСH3); 6.92 (2H, d, J = 8.0, H-3',5');
7.45 (1H, t, J = 8.0, H-8); 7.48 (1H, t, J = 8.0, H-7); 7.71 (2H, d, J = 8.0, H-2',6');
7.85 (1H, t, J = 8.0, H-9); 8.00 (1H, d, J = 8.0, H-6); 11.04 (1Н, s, NH)
3.74 (2Н, s, СН2); 3.84 (3Н, s, 3'-ОСH3); 3.87 (3Н, s, 4'-ОСH3);
6.91 (1H, d, J = 8.0, H-5'); 7.31 (1H, d, J = 8.0, H-6'); 7.37 (1H, s, H-2');
7.47 (1H, t, J = 8.0, H-8); 7.50 (1H, t, J = 8.0, H-7); 7.88 (1H, d, J = 8.0, H-9);
8.03 (1H, d, J = 8.0, H-6); 11.06 (1Н, s, NH)
3.74 (2Н, s, СН2); 7.09 (1H, t, J = 4.0, H-4'); 7.49-7.54 (3H, m, H-7,8,5');
7.62 (1H, d, J = 4.0, H-3'); 7.92 (1Н, d, J = 8.0, H-9); 8.03 (1Н, d, J = 8.0, Н-6);
11.16 (1Н, s, NH)
15e
15f
15g
2.42 (3Н, s, 4'-СH3); 2.54 (3Н, s, 7-СH3); 3.73 (2Н, s, СН2); 7.24 (2H, d, J = 8.0, H-3',5');
7.31 (1H, d, J = 8.0, H-8); 7.66 (2H, d, J = 8.0, H-2',6'); 7.77 (1H, d, J = 8.0, H-9);
7.83 (1H, s, H-6); 11.18 (1Н, s, NH)
2.55 (3Н, s, 7-СH3); 3.72 (2Н, s, СН2); 3.84 (3Н, s, 3'-ОСH3); 6.97 (1H, d, J = 8.0, H-4');
7.27-7.34 (4H, m, H-8,2',5',6'); 7.72 (1H, d, J = 8.0, H-9); 7.80 (1H, s, H-6);
11.13 (1Н, s, NH)
2.47 (3Н, s, 4'-СH3); 3.63 (3Н, s, ОСH3); 4.13 (2Н, s, СН2); 7.32 (2H, d, J = 8.0, H-3',5');
7.46-7.53 (2H, m, H-5,6); 7.78 (2H, d, J = 8.0, H-2',6'); 7.89-7.93 (2H, m, H-4,7)
16a
16b
2.46 (3Н, s, 4'-СH3); 2.52 (3Н, s, 5-СH3); 3.63 (3Н, s, ОСH3); 4.10 (2Н, s, СН2);
7.28 (1H, d, J = 8.0, H-3',5'); 7.32 (1H, d, J = 8.0, H-6); 7.64 (1H, s, H-4);
7.74-7.78 (2H, m, H-7,2',6')
2.56 (3Н, s, 5-СH3); 3.68 (3Н, s, ОСH3); 3.90 (3Н, s, 3'-ОСH3); 4.16 (2Н, s, СН2);
7.20 (1H, d, J = 8.0, H-4'); 7.36 (1H, s, H-2'); 7.39 (1H, d, J = 8.0, H-6);
7.45 (2H, m, H-5',6'); 7.73 (1H, s, H-4); 7.84 (1H, d, J = 8.0, H-7)
16c
______
*Spectrum recorded in CDCl3–CF3COOH.
1377

TABLE 3. Mass Spectra of Compounds 4b, 10, 15a-g
Com-
pound
m/z (Irel, %)*
230 [M]+ (100), 214 (13), 201 (69), 185 (38), 171 (19), 160 (38), 145 (20), 127 (15),
4b
115 (52), 101 (34), 93 (19), 74 (22), 69 (37), 63 (20), 57 (10), 51 (19), 45 (37), 39 (20)
259 (12), 258 [М]+ (100), 242 (11), 229 (27), 216 (18), 214 (5), 201 (7), 186 (6), 115 (5), 44 (5)
292 [М]+ (100), 263 (65), 250 (15), 234 (27), 189 (9), 132 (12), 117 (12), 89 (7),
10
15a
77 (13), 63 (7), 51 (11), 39 (8)
308 (6), 307 (22), 306 [M]+ (100), 305 (27), 278 (14), 277 (63), 264 (12), 263 (8),
15b
249 (6), 247 (5), 235 (10), 234 (20), 202 (5), 145 (5), 139 (8), 138 (9), 131 (9), 123 (5),
117 (10), 104 (5), 102 (5), 101 (5), 91 (8), 78 (6), 69 (5), 45 (5)
324 (5), 323 (18), 322 [М]+ (100), 321 (17), 320 (6), 294 (11), 293 (58), 292 (8), 280 (8),
15c
279 (9), 265 (11), 264 (6), 250 (7), 235 (5), 234 (9), 222 (9), 221 (23), 189 (6), 161 (5),
147 (8), 146 (5), 111 (5), 110 (8), 45 (8)
354 (7), 353 (22), 352 [M]+ (100), 351 (9), 324 (7), 323 (38), 309 (7), 295 (6), 221 (9),
15d
208 (7), 162 (9), 161 (6), 104 (8)
300 (8), 299 (19), 298 [М]+ (100), 297 (5), 283 (6), 271 (6), 270 (13), 269 (64), 268 (6),
15e
256 (7), 255 (12), 254 (8), 241 (11), 240 (15), 208 (6), 135 (7), 120 (13), 45 (8), 44 (8)
320 [М]+ (100), 291 (54), 278 (13), 248 (9), 145 (10), 131 (8), 129 (8), 91 (7)
338 (7), 337 (30), 336 [М]+ (100), 335 (17), 308 (10), 307 (48), 294 (10), 293 (7),
15f
15g
264 (5), 235 (5), 154 (6), 45 (5)
_______
* Peaks reported with intensities greater than 5% that of the base peak.
Hence, we have shown that the route of heterocyclization of 2-acyl(aroyl)benzo[b]thiophene-3-acetic
acids with hydrazine hydrate depends on the substituents in the acyl fragment, and the reaction requires an acid
catalyst. The 2-acetylbenzo[b]thiophene-3-acetic acid derivatives do not give cyclic products upon treatment
with hydrazine hydrate, yielding only the corresponding hydrazones, treatment of which with organic acids
leads to formation of six-membered structures – 2-amino-1,6-dimethylbenzothieno[2,3-c]pyridin-3-ones, while
aryl substituents favour the production of 5H-benzothieno[2,3-d][1,2]diazepin-4-ones.
EXPERIMENTAL
1H NMR spectra were recorded on a Bruker DRX-400 instrument (400 MHz) using DMSO-d6 with
TMS as internal standard. EI mass spectra were recorded on an MX-1321 mass spectrometer with ionization
energy 70 eV, ionization chamber temperature 220ºC, and direct sample injection. Elemental analysis was
performed on a Vario MICRO cube CHN analyzer, while sulfur was determined by titration as sulfate anion
after combustion in oxygen. Melting points were determined on a Boetius hot stage apparatus. The properties of
the products synthesized are given in Tables 1-3.
2-Acetyl-5-methylbenzo[b]thiophene-3-acetic Acid (1a) and 5-Methyl-2-propionylbenzo[b]thiophene-
3-acetic Acid (1b) (General Method). Compound 7b,c (0.010 mol) was added to 30 ml of an aqueous solution
containing NaOH (1.0 g, 0.025 mol) and heated to complete dissolution. The solution was cooled and acidified with
formic acid. The precipitate formed was filtered off, washed with water, dried, and recrystallized from 2-PrOH.
2-Acetyl-5-methylbenzo[b]thiophene-3-acetic Acid Hydrazone (2). A. Compound 1a (2.48 g, 0.01 mol)
was dissolved in 5% aqueous NaHCO3 solution (30 ml), and hydrazine hydrate (2.5 g, 0.05 mol) was added.
The mixture was refluxed for 1 h, cooled, and acidified to pH < 7 using acetic acid. The precipitate was filtered
off and recrystallized from 2-PrOH.
B. Compound 1a (2.48 g, 0.01 mol) was dissolved in EtOH (30 ml), and hydrazine hydrate (2.5 g, 0.05 mol)
was added. The mixture was refluxed for 1 h, ethanol (20 ml) was distilled off, water (20 ml) was added, and the
product was acidified to pH < 7 using acetic acid. The precipitate formed was filtered off and recrystallized
from 2-PrOH.
1378

5-Methyl-2-propionylbenzo[b]thiophene-3-acetic Acid Azine (3). Obtained similarly to compound 2
(method A) from compound 1b and recrystallized from aqueous DMSO.
2-Amino-1,6-dimethylbenzothieno[2,3-c]pyridin-3(2H)-one (4a). A. Dicyclohexylcarbodiimide (0.72 g,
3.5 mmol) was added to a solution of the hydrazone 2 (0.73 g, 3.0 mmol) in CH2Cl2 (20 ml). The mixture was
stirred for 5 h and the precipitated dicyclohexylurea was filtered off and washed with CH2Cl2. The filtrate was
evaporated in vacuo and recrystallized from MeOH.
B. The corresponding 2-acetylbenzo[b]thiophene-3-acetic acid amide hydrazone 11a,b, 12a,b [16] (1 g)
was dissolved in AcOH (20 ml) (in the case of compounds 11a,b) or trifluoroacetic acid (20 ml) (for compounds
12a,b) and refluxed for 1 h. The mixture was cooled, diluted with water (50 ml), and the reaction mixture was
neutralized by the addition of aqueous ammonia solution to pH > 7. The precipitate formed was filtered off,
washed with water, and recrystallized from MeOH
C. Hydrazine acetate (4.50 g, 0.05 mol) was added to a solution of compound 7b (2.30 g, 0.01 mol) in
2-PrOH (30 ml), and the reaction mixture was refluxed for 5 h. The target product precipitated during the
reaction. The mixture was cooled, the precipitate was filtered off, washed with 2-PrOH and water, and
recrystallized from MeOH.
D. Obtained similarly from methyl 2-acetyl-5-methylbenzo[b]thiophene-3-acetate (9b).
2-Amino-1-methylbenzothieno[2,3-c]pyridin-3(2H)-one (4b). A. Hydrazine acetate (4.50 g, 0.05 mol)
was added to a suspension of the pyrilium tetrafluoroborate 8 (3.45 g, 0.01 mol) in 2-PrOH (30 ml), and the
reaction mixture was refluxed for 5 h. The target product precipitated during the reaction. The mixture was
cooled, the precipitate was filtered off, washed with 2-PrOH and water, and recrystallized from MeOH.
B. Obtained similarly from 1-methylbenzothieno[2,3-c]pyr-3-one (7a).
C. Obtained similarly from methyl 2-acetylbenzo[b]thiophene-3-acetate (9a).
2-Acetyl-5-methylbenzo[b]thiophene-3-acetic Acid Phenylhydrazone (5). Phenylhydrazine (1.62 g,
0.015 mol) was added to a solution of compound 1a (2.48 g, 0.01 mol) in 2-PrOH, and the reaction mixture was
refluxed for 1 h. The reaction mixture was cooled, and the precipitate formed was filtered off, washed with cold
2-PrOH, and recrystallized from MeOH.
1,6-Dimethyl-2-phenylaminobenzothieno[2,3-c]pyridin-3(2H)-one (6). Obtained by cyclization of
phenylhydrazone 5 by a method analogous to method A for preparing compound 4a. Recrystallized from
2-PrOH.
1-Methylbenzothieno[2,3-c]pyr-3-one (7a), 1,6-dimethylbenzothieno[2,3-c]pyr-3-one (7b), and
1-ethyl-6-methylbenzothieno[2,3-c]pyr-3-one (7c) were prepared by acylation of benzo[b]thiophene-3-acetic
acid and 5-methylbenzo[b]thiophene-3-acetic acid using acetic and propionic anhydrides in the presence of
BF3·Et2O via the method reported in [17].
3-Acetylamino-1,6-dimethylbenzothieno[2,3-c]pyrilium Tetrafluoroborate (8) were prepared by
acylation of benzothiophene-3-acetonitrile with acetic anhydride in the presence of BF3·Et2O, using the method
reported in [18].
Methyl 2-acetylbenzo[b]thiophene-3-acetate (9a) and methyl 2-acetyl-5-methylbenzo[b]thiophene-
3-acetate (9b) were prepared by esterification of the corresponding acids, using the method reported in [19].
1-Ethyl-7-methylbenzothieno[2,3-d][1,2]diazepin-4-one (10). Hydrazine acetate (4.50 g, 0.05 mol)
was added to a solution of compound 7c (2.44 g, 0.01 mol) in 2-PrOH (30 ml), and the reaction mixture was
refluxed for 5 h. The reaction mixture was evaporated to half volume and diluted with water (20 ml). The
precipitate formed was filtered off, washed with water, and recrystallized from 2-PrOH.
Hydrazones of the 2-Acetyl-5-methylbenzo[b]thiophene-3-acetic Acid Dimethylamide (11a) and
2-Acetyl-5-methylbenzo[b]thiophene-3-acetic Acid Morpholide (11b) (General Method). Hydrazine hydrate
(5 ml) was added to a solution of the corresponding 2-acetyl-5-methylbenzo[b]thiophene-3-acetic acid amides
[16] (0.01 mol) in 2-PrOH (50 ml), and the reaction mixture was refluxed for 3 h. The reaction mixture was
cooled, and water (50 ml) was added. The precipitate was filtered off, washed with water, and recrystallized
from 2-PrOH.
1379

Hydrazones of 2-Acetyl-5-methylbenzo[b]thiophene-3-acetic Acid 4-Methylphenylamide (12a) and
2-Acetyl-5-methylbenzo[b]thiophene-3-acetic Acid 4-Methoxyphenylamide (12b) (General Method).
Prepared similarly from the corresponding 4-methylphenyl- and 4-methoxyphenylamides of 2-acetyl-
5-methylbenzo[b]thiophene-3-acetic acid [15].
1-Arylbenzothieno[2,3-c]pyr-3-ones 13a-e (General Method). Methyl benzothiophene-3-acetate
(6.1 g, 0.03 mol) and the corresponding benzoic acid (0.05 mol) were added to polyphosphoric acid (prepared
from 85% H3PO4 (22 ml) and P2O5 (44 g)). The mixture was stirred at 100ºC for 1.5 h. The reaction mixture
was poured into water (400 ml), and K2CO3 was added until weakly alkaline (pH 9). The precipitate was filtered
off and recrystallized from MeOH.
2-Aroylbenzo[b]thiophene-3-acetic Acids 14a-g (General Method). Compounds 13a-e (0.010 mol)
were added to an aqueous solution (30 ml) containing NaOH (1.0 g, 0.025 mol) and heated until full dissolution.
The solution was cooled and acidified with formic acid. The precipitated compounds 14a-e were filtered off,
washed with water, dried, and recrystallized from 2-PrOH.
Compounds 14b,f,g were prepared similarly from esters 16a-c.
1-Aryl-3,4-dihydro-5H-benzothieno[2,3-d][1,2]diazepin-4-ones 15a-g (General Method). A. A
solution of the corresponding 1-arylbenzothieno[2,3-c]pyrone 13a-e (1 mmol) in ethyl cellosolve (10 ml) was
refluxed for 20 h with hydrazine hydrate (5 mmol) in the presence of catalytic amounts (3-4 drops) of AcOH.
The reaction mixture was diluted with water. The precipitated compounds 15a-e were filtered off, washed with
water, and recrystallized from 2-PrOH.
B. Compounds 15a-g were prepared similarly from the 2-aroylbenzo[b]thiophene-3-acetic acids 14a-g.
C. Compounds 15b,f,g were prepared similarly from the 2-aroylbenzo[b]thiophene-3-acetic acid esters
16a-c.
Methyl 2-aroylbenzo[b]thiophene-3-acetates 16a-c (General Method). A solution of methyl
benzo[b]thiophene-3-acetate (1.10 g, 5.0 mmol) in CH2Cl2 (5 ml) was added to an acylating mixture prepared
from SnCl4 (1.70 g, 6.5 mmol) and the corresponding aroyl chloride (6.0 mmol) in dry CH2Cl2 (10 ml). The
mixture was stirred at 25-30ºC for 3 h. The reaction mixture was poured into a mixture of ice (40 g) and HCl
(7 ml) and extracted with CH2Cl2. The extract was washed with a dilute solution of NaHCO3, water, dried over
Na2SO4, and evaporated. The residue was recrystallized from 2-PrOH.
X-Ray Structural Analysis of Compound 10. Crystals of compound 10 (C14H14N2OS, M 258.33) are
tetragonal. At 293 K: a 19.1490(4), b 19.1490(4), c 7.3447(3) Å, V 2693.19(14) Å3, Z 8; space group P-421c,
dcalc 1.274 g/cm3; MoK 0.230 mm-1, F(000) 1088. The unit cell parameters and intensities of 12880
reflections (3882 independent, Rint 0.026) were measured on an Xcalibur-3 diffractometer (MoK radiation,
CCD detector, graphite monochromator, -scanning, 2max 60º). The structure was solved by the direct method
using the SHELXTL software package [20]. The positions of the hydrogen atoms were solved from electron
density difference synthesis and refined isotropically. The structure was refined by F2 full-matrix least-squares
analysis in the anisotropic approximation for non-hydrogen atoms to wR2 0.102 for 3834 reflections (R1 0.045
for 3069 reflections with F > 4(F), S 1.026). The final atomic coordinates, geometric parameters of the
molecule, and crystallographic data have been placed in the Cambridge Crystallographic Data Center as deposit
CCDC 851691.
REFERENCES
1.
2.
3.
4.
G. De Sarro, A. Chimirri, and B. S. Meldrum, Eur. J. Pharmacol., 451, 55 (2002).
A. De Sarro, G. De Sarro, R. Gitto, S. Grasso, N. Micale, and M. Zappalà, Farmaco, 54, 178 (1999).
R. Gitto, M. Zappalà, G. De Sarro, and A. Chimirri, Farmaco, 57, 129 (2002).
S. Quartarone, R. Caruso, V. Orlando, E. Russo, G. De Sarro, and A. Chimirri, Farmaco, 59, 353
(2004).
1380

5.
6.
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