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Vinogradov et al.
washed with water, dissolved in chloroform, and dried over
MgSO4. The solvent was evaporated and the residue was
chromatographed on a column with silica gel (Silpearl,
CHCl3). Product 7 was obtained in a yield of 0.17 g (20%),
Methyl 2-[3-(1,3-dioxolan-2-yl)-6-nitrobenzo[d]isoxazol-4-
yl]thioacetate (9c), m.p. 100102 °C (EtOH). 1H NMR: 3.73
(s, 3 H, OMe); 4.104.21 (m, 4 H, 2 CH2); 4.29 (s, 2 H,
CH2); 6.50 (s, 1 H, OCHO); 8.07 (s, 1 H, H(5)); 8.51 (s, 1 H,
H(7)). Found (%): C, 45.76; H, 3.61. C13H12N2O7S. Calcu-
lated (%): C, 45.88; H, 3.55.
Ethyl 2-[3-(1,3-dioxolan-2-yl)-6-nitrobenzo[d]isoxazol-4-
yl]thioacetate (9d), m.p. 8990 °C (EtOH). 1H NMR: 1.25 (t,
3 H, Me, 3J = 7.0 Hz); 4.104.32 (m, 8 H, 4 CH2 (Et,
dioxolane, CH2C=O)); 6.51 (s, 1 H, OCHO); 8.10 (s, 1 H,
H(5)); 8.43 (s, 1 H, H(7)). 13C NMR: 13.9, 34.7, 61.3, 64.9,
96.7, 102.7, 116.0, 121.4, 135.2, 149.0, 156.0, 162.6, 168.0.
Found (%): C, 47.49; H, 4.17; S, 8.88. C14H14N2O7S. Calcu-
lated (%): C, 47.45; H, 3.98; S, 9.05.
6-Nitro-4-phenylthiobenzo[d]isoxazole-3-carbaldehyde
O-methyloxime (9e), m.p. 117118 °C (EtOH). 1H NMR: 4.05
(s, 3 H, OMe); 7.507.60 (s, 6 H, Ph, H(5)); 8.57 (s, 1 H,
CH=N); 8.74 (s, 1 H, H(7)). 13C NMR: 62.7, 104.0, 117.9,
121.8, 129.9, 130.5, 133.6, 135.6, 138.2, 149.2, 151.9, 162.8.
Found (%): C, 54.54; H, 3.43; S, 9.62. C15H11N3O4S. Calcu-
lated (%): C, 54.70; H, 3.37; S, 9.74.
1
m.p. 8890 °C. H NMR: 4.084.30 (m, 4 H, 2 CH2); 6.25
5
(d, 1 H, OCHO, JHF = 1.5 Hz); 8.05 (d.d, 1 H, H(5),
4
3JHF = 9.2 Hz, JHH = 1.5 Hz); 8.58 (d, 1 H, H(7),
4JHH = 1.5 Hz). 13C NMR: 65.4 (s, OCH2CH2O); 96.1
4
(s, OCHO); 102.9 (d, C(7), JCF = 5.0 Hz); 105.7 (d, C(5),
2JCF = 25.1 Hz); 112.9 (d, C(3a), 2JCF = 22.5 Hz); 149.7 (d,
3
1
C(6), JCF = 8.2 Hz); 154.0 (d, C(4), JCF = 251.4 Hz);
3
155.1 (d, C(3), JCF = 5.5 Hz); 163.7 (d, C(7a),
4JCF = 8.1 Hz). 19F NMR: 104.31. Found (%): C, 47.02;
H, 2.80. C10H7FN2O5. Calculated (%): C, 47.25; H, 2.78.
Synthesis of compounds 8ac (general procedure). Sodium
azide (0.1 g, 1.53 mmol) was added to a solution of 4,6-di-
nitrobenzo[d]isoxazole 6añ (1.5 mmol) in DMF (5 mL). The
reaction mixture was stirred at 20 °C for 24 h, poured into
water, and acidified to pH 2. The precipitate that formed was
filtered off, washed with water, and recrystallized from EtOH.
The yields of the products are given in Scheme 4.
4-Azido-3-(1,3-dioxolan-2-yl)-6-nitrobenzo[d]isoxazole
(8a), m.p. 7274 °C. 1H NMR: 4.104.40 (m, 4 H, (CH2)2);
6.55 (s, 1 H, OCHO); 7.95 (s, 1 H, H(5)); 8.25 (s, 1 H, H(7)).
13C NMR: 65.1, 96.5, 102.0, 108.4, 115.6, 136.3, 149.6,
155.8, 163.4. IR, ν/cm1: 2140 (N3); 1550, 1360 (NO2).
Found (%): C, 43.51; H, 2.39. C10H7N4O5. Calculated (%):
C, 43.33; H, 2.55.
Methyl 2-[3-(methoxyiminomethyl)-6-nitrobenzo[d]isoxa-
zol-4-yl]thioacetate (9f), m.p. 111112 °C (EtOH). 1H NMR:
3.70 (s, 3 H, Me); 4.08 (s, 3 H, NOMe); 4.33 (s, 2 H, CH2);
8.10 (s, 1 H, H(5)); 8.62 (s, 1 H, CH=N); 8.75 (s, 1 H, H(7)).
13C NMR: 34.8, 52.7, 62.8, 103.9, 117.4, 122.2, 134.6, 138.6,
149.4, 152.0, 162.4, 169.1. Found (%): C, 44.14; H, 3.63; S, 9.72.
C12H11N3O6S. Calculated (%): C, 44.31; H, 3.41; S, 9.86.
6-Nitro-4-phenylthiobenzo[d]isoxazole-3-carbaldehyde
N-phenylhydrazone (9g), m.p. 206207 °C (EtOH). 1H NMR:
6.92 (t, 1 H, Ph, 3J = 7.4 Hz); 7.157.35 (m, 4 H, Ph); 7.52 (s,
1 H, H(5)); 7.607.70 (m, 5 H, Ph); 8.40 (s, 1 H, CH=N);
8.55 (s, 1 H, H(7)); 11.23 (s, 1 H, NH). 13C NMR: 102.0,
111.7, 115.1, 119.3, 121.9, 128.1, 129.0, 129.4, 130.5, 131.6,
133.1, 135.7, 144.0, 149.0, 154.7, 162.9. Found (%): C, 61.24;
H, 3.42. C20H14N4O3S. Calculated (%): C, 61.53; H, 3.61.
4-Azido-6-nitrobenzo[d]isoxazole-3-carbaldehyde O-methyl-
1
oxime (8b), m.p. 164166 °C. H NMR: 4.08 (s, 3 H, Me);
8.05 (s, 1 H, H(5)); 8.42 (s, 1 H, CH=N); 8.47 (s, 1 H, H(7)).
13C NMR: 62.7, 102.3, 108.9, 116.1, 136.4, 137.3, 149.8, 150.4,
163.3. IR, ν/cm1: 2135 (N3); 1540, 1360 (NO2). Found (%):
C, 41.38; H, 2.25. C9H6N6O4. Calculated (%): C, 41.23; H, 2.31.
4-Azido-6-nitrobenzo[d]isoxazole-3-carbaldehyde N-phenyl-
1
hydrazone (8ñ), m.p. 214215 °C. H NMR: 6.99 (m, 1 H,
Ph); 7.15 (m, 2 H, Ph); 7.32 (m, 2 H, Ph); 8.00 (s, 1 H, H(5));
8.25 (s, 1 H, CH=N); 8.45 (s, 1 H, H(7)); 11.22 (s, 1 H, NH).
13C NMR: 102.3, 109.1, 112.9, 118.6, 120.7, 122.7, 129.3,
136.4, 144.1, 149.6, 153.6, 163.3. Found (%): C, 52.18; H, 2.73.
C14H9N7O3. Calculated (%): C, 52.02; H, 2.81.
Methyl
2-[6-nitro-3-(phenylhydrazonomethyl)ben-
zo[d]isoxazol-4-yl]thioacetate (9h), m.p. 210211 °C (EtOH).
1H NMR: 3.67 (s, 3 H, Me); 4.30 (s, 2 H, CH2); 6.94 (t, 1 H,
Ph, 3J = 7.4 Hz); 7.157.35 (m, 4 H, Ph); 8.05 (s, 1 H, H(5));
8.32 (s, 1 H, CH=N); 8.50 (s, 1 H, H(7)); 11.21 (br.s, 1 H,
NH). 13C NMR: 34.4, 52.7, 103.2, 112.9, 115.7, 120.5, 121.8,
123.3, 129.3, 134.9, 144.0, 149.1, 154.7, 162.6, 169.0.
Found (%): C, 52.89; H, 3.51. C17H14N4O5S. Calculated (%):
C, 52.84; H, 3.65.
3-(1,3-Dioxolan-2-yl)-6-nitro-4-phenoxybenzo[d]isoxazole
(10), m.p. 134135 °C (EtOH). 1H NMR: 4.004.12 (m, 4 H,
(CH2)2); 6.44 (s, 1 H, CH); 7.257.40 (m, 4 H, H(5), Ph);
7.63 (m, 2 H, Ph); 8.45 (s, 1 H, H(7)). 13C NMR: 65.4, 96.8,
100.2, 103.9, 115.1, 120.4, 126.0, 130.6, 150.1, 152.7, 153.8,
156.3, 164.0. Found (%): C, 58.78; H, 3.76. C16H12N2O6.
Calculated (%): C, 58.54; H, 3.68.
Synthesis of compounds 11a,b (general procedure). A 3 M
solution of MeONa in MeOH (0.5 mL) was added to a suspen-
sion of 4,6-dinitrobenzo[d]isoxazole 6a,b (1.5 mmol) in MeOH
(10 mL). The reaction mixture was stirred at 20 °C for 24 h and
poured into water. The precipitate that formed was filtered off,
washed with water, and recrystallized from EtOH. The yields of
the products are given in Scheme 6.
Synthesis of compounds 9ah and 10 (general procedure).
The corresponding thiol or PhOH (1.5 mmol) and K2CO3
(0.21 g, 1.5 mmol) were added to a solution of 4,6-dinitro-
benzo[d]isoxazole 6ac (1.5 mmol) in NMP (5 mL). The
reaction mixture was stirred at 20 °C for 24 h (in the case of
PhOH, at 80 °C), poured into water, and acidified to pH 2. The
precipitate that formed was filtered off, washed with water, and
recrystallized from EtOH. The yields of the products are given
in Schemes 5 and 6.
3-(1,3-Dioxolan-2-yl)-6-nitro-4-phenylthiobenzo[d]isoxa-
zole (9a), m.p. 133134 °C (EtOH). 1H NMR: 4.054.30 (m,
4 H, 2 CH2); 6.51 (s, 1 H, OCHO); 7.27 (s, 1 H, H(5));
7.507.74 (m, 5 H, Ph); 8.40 (s, 1 H, H(7)). 13C NMR: 65.1
(2 CH2); 96.7 (CHO); 103.0 (C(7)); 116.0 (C(5)); 120.6 (C(3a));
129.2 (Ph); 130.4 (Ph); 130.6 (Ph); 134.9 (Ph); 137.0 (C(4));
149.2 (C(6)); 156.3 (C(3)); 163.1 (C(7a)). Found (%): C, 56.03;
H, 3.24. C16H12N2O5S. Calculated (%): C, 55.81; H, 3.51.
4-Benzylthio-3-(1,3-dioxolan-2-yl)-6-nitrobenzo[d]isoxa-
zole (9b), m.p. 106107 °C (EtOH). 1H NMR: 4.024.23 (m,
4 H, 2 CH2); 4.50 (s, 2 H, SCH2); 6.51 (s, 1 H, OCHO);
7.187.42 (m, 3 H, Ph); 7.49 (m, 2 H, Ph); 8.05 (s, 1 H,
H(5)); 8.50 (s, 1 H, H(7)). 13C NMR: 36.8, 65.0, 96.9, 102.4,
115.7, 121.4, 127.5, 128.5, 129.0, 135.2, 136.4, 149.0, 156.3,
162.7. Found (%): C, 56.69; H, 3.81. C17H14N2O5S. Calcu-
lated (%): C, 56.98; H, 3.94.
3-(1,3-Dioxolan-2-yl)-4-methoxy-6-nitrobenzo[d]isoxazole
1
(11a), m.p. 150152 °C (EtOH). H NMR: 4.034.19 (m,
4 H, 2 CH2); 4.08 (s, 3 H, Me); 6.45 (s, 1 H, OCHO); 7.65
(s, 1 H, H(5)); 8.20 (s, 1 H, H(7)). 13C NMR: 57.0,
65.2, 96.8, 98.6, 99.9, 114.0, 150.6, 154.4, 156.4, 163.5.
Found (%): C, 49.42; H, 3.71. C11H10N2O6. Calculated (%):
C, 49.63; H, 3.79.