Studies on the reactivity of new types of tetracyclic-1,5-benzoxazepines: Part V

Article abstract of DOI:10.1002/jhet.5570380211

The syntheses of tetracyclic 1,5-benzoxazepines 3a-e from heterocyclic β-chloroaldehydes 1a-e and 2-aminophenol are reported herein (Scheme I). Attempted lithium aluminium hydride (LiAlH₄) reduction of the imine double bond in 3a-e failed to fu

Full text of DOI:10.1002/jhet.5570380211

Mar-Apr 2001
Studies on the Reactivity of New Types of Tetracyclic-1,5-
Benzoxazepines: Part V
383
Batchu Chandra Sekhar,[a]* Devalla Venkata Ramana,[b] and Sukuru Raghu Ramadas
Department of Chemistry, Indian Institute of Technology, Chennai – 600 036, India
[a] Address for Correspondence: Dr. Reddy's Research Foundation, 7-1-27, Ameerpet, Hyderabad - 500 050, India.
[b] Emeritus Scientist (CSIR, India).
Received March 6, 2000
The syntheses of tetracyclic 1,5-benzoxazepines 3a-e from heterocyclic β-chloroaldehydes 1a-e and
2-aminophenol are reported herein (Scheme I). Attempted lithium aluminium hydride (LiAlH ) reduction
4
of the imine double bond in 3a-e failed to furnish the corresponding saturated compounds 5a-e. Attempted
catalytic hydrogenation of 3a-e in the presence of acetic acid and acetic anhydride gave surprisingly only
the acetoxy derivatives 6a-e in high yields (Scheme II). Base catalysed hydrolysis of acetoxy derivatives
6a-e furnished, as expected, the corresponding phenolic derivatives 7a-e, in moderate yields. Attempted
cyclofunctionalization of 3a-e either with mercaptoacetic acid or its methyl ester to obtain the new penta-
cyclic heterocycles 4a-e was, however, not successful.
J. Heterocyclic Chem., 38, 383 (2001).
Introduction.
Although condensed seven membered heterocycles
have been the subject of intensive study on their syntheses
in the light of their antihelmentic [1] activity, surprisingly
little work has been reported in the literature [1-8] on the
preparation of such heterocycles. In a broad program to
synthesize such polycyclic heterocycles, and in continua-
tion of our studies [9-12] concerning the synthetic utility
of heterocyclic β-chloroaldehydes, the syntheses of new
tetracyclic 1,5-benzoxazepines have been achieved
successfully in a simple way. This paper describes the
synthesis and reactivity of these tetracyclic-1,5-benzox-
azepines 3a-e as detailed below.
Results and Discussion.
Heterocyclic β-chloroaldehydes [9-12] (1a-e) were
condensed with 2-aminophenol to yield the intermediate
imino derivatives (2a-e), as expected, in good yields.
Cyclization of 2a-e in refluxing DMF gave the anticipated
1,5-benzoxazepines (3a-e) in good yields (Scheme I).
The structures assigned to these tetracyclic heterocycles
(3a-e) were confirmed by spectroscopic and analytical
1
data. An interesting feature of the H-nmr spectra of these
1
1,5-benzoxazepines (3a-e) is the high field H-nmr signal
of the iminic protons in comparison with that shown by
the corresponding aldimines (-CH=N-) in 2a-e.

Vol. 38
B. C. Sekhar, D. V. Ramana, and S. R. Ramadas
384
(1.2 g, 80%), mp 158-160°; ir: ν OH 3420, ν CN 1630, 1240
Paradisi and co-workers [3,4] have also made similar
observations in 6H-quino[2,3-b][1,5]benzoxazepines. The
attempted reduction of the imine double bond in 3a-e
-1
1
cm ; H-NMR: δ 3.92 (s, 3H, Ar-OMe), 6.9 - 7.66 (m, 7H,
+
aromatic), 8.73 (s, 1H, -CH=N-); ms: m/z 301 (M ), 266
+
+
(M -Cl), 265 (M -Cl-H). UV-Vis: λ
(methanol) (logε)/nm
max
using LiAlH to generate the corresponding dihydro
4
204 (2.82), 241 (2.28), 337 (2.72) and 375 (2.83).
Anal. Calcd. for C ClNO : C, 63.78; H, 3.98; N, 4.65.
derivatives (5a-e), however, was unsuccessful. The
attempted cyclofunctionalization of the imine double
bond in 3a-e with either mercaptoacetic acid, its methyl
ester under the influence of p-toluene sulfonic acid (PTS),
or Nafion H (super acid) as catalysts to furnish the
expected pentacyclic heterocycles (4a-e) was also unsuc-
cessful (Scheme I). Catalytic hydrogenation of 3a-e in the
presence of palladium on carbon (Pd/C) in acetic acid and
acetic anhydride medium failed to give the desired prod-
ucts 5a-e. Instead, hydrogenolysis occurred to yield the
acetoxy derivatives (6a-e) (Scheme II). In order to
confirm the structure of the acetoxy derivatives (6a-e),
these were subjected to hydrolysis with 10% alcoholic
KOH to obtain the expected phenolic derivatives (7a-e) in
moderate yields. The presence of a singlet at δ 2.55 ppm
H
16 12
3
Found: C, 64.10; H, 3.51; N, 4.39.
2-[[(4-Chloro-2H-1-benzopyran-3-yl)methylene]amino]phenol
(2b).
This compound was obtained from 4-chlorochromene-3-
carboxaldehyde (1b), (0.97 g, 5 mmoles) and 2 aminophenol
(0.54 g, 5 mmoles). Recrystallization of the crude product from
carbon tetrachloride gave a yellow crystalline solid (1.11 g,
-1
78%), mp 156-158°; ir: ν OH 3500, ν CN 1640, 1420 cm ;
1
H-NMR: δ 5.26 (s, 2H, -O-CH -), 6.68 - 7.76 (m, 8H,
2
+
aromatic), 8.87 (s, 1H, -CH=N-); ms: m/z 285 (M ), 268
(M -OH), 250 (M -Cl), 249 (M -Cl-H). ). UV-Vis: λ
(methanol) (logε)/nm 205 (3.00), 241 (2.52) and 424 (2.40).
+
+
+
max
Anal. Calcd. for C
H ClNO : C, 67.36; H, 4.21; N, 4.91.
16 12 2
Found: C, 66.93; H, 3.95; N, 4.71.
1
in the H nmr spectra of 6a-e confirmed the presence of
2-[[(4-Chloro-2H-1-benzothiopyran-3-yl)methylene]amino]-
phenol (2c).
the acetoxy group (OCOMe) group. The typical absence
1
of this signal in the H nmr spectra of 7a-e proved the
This compound was obtained from 4-chlorothiochromene-3-
carboxaldehyde (1c), (1.05 g, 5 mmoles) and 2 aminophenol
(0.54 g, 5 mmoles). Recrystallization of the crude product from
carbon tetrachloride gave a light orange yellow solid (1.12 g,
assigned structure for 7a-e.
EXPERIMENTAL
-1
75%), mp 151-152°; ir: ν OH 3350, ν CN 1620, 1430 cm ;
1
H-NMR: δ 4.05 (s, 2H, -S-CH -), 7.3 - 7.8 (m, 8H, aromatic),
2
Melting points were determined with a Büchi 535 melting
point apparatus and reported uncorrected. UV-Vis spectra were
measured with a Shimadzu UV-2100S spectrophotometer. The ir
spectra (potassium bromide) were recorded with a Perkin-Elmer
+
+
9.4 (s, 1H, -CH=N-); ms: m/z 301 (M ), 266 (M -Cl), 265
(M -Cl-H). UV-Vis: λ
(2.73) and 273 (2.56), 321 (2.55) and 394 (2.51).
+
(methanol) (logε)/nm 206 (2.82), 244
max
Anal. Calcd. for C ClNOS: C, 63.78; H, 3.98; N, 4.65.
H
16 12
1
983 spectrophotometer. The H nmr spectra were measured with
Found: C, 63.54; H, 3.79; N, 4.40.
a Varian EM-390 (90 MHz) spectrophotometer, and Bruker (400
MHz) using deuterochloroform as the solvent and tetramethyl-
silane as the internal standard. The mass spectra were recorded
on a Varian MAT CH-7 and Finnigan MAT 8230 spectrometer
operating in electron impact mode at 70 eV. ACME silica gel
(60 - 120 mesh) was used for column chromatography.
Anhydrous sodium sulphate was used as the drying agent.
Absolute ethanol and 2-aminophenol were purchased from
Merck. The heterocylic chloroaldehydes 1a-e were prepared
according to literature procedures [9-12].
2-[[(5-Chloro-2,3-dihydro-1-benzoxepin-4-yl)methylene]-
amino]phenol (2d).
This compound was obtained from 5-chloro-2,3-dihydro-1-
benzoxepin-4-carboxaldehyde (1d), (1.04 g, 5 mmoles) and 2
aminophenol (0.54 g, 5 mmoles). Recrystallization of the crude
product from carbon tetrachloride gave a light orange crystalline
solid (0.89 g, 60%), mp 162-164°; ir: ν OH 3300, ν CN 1620,
-1
1
1400 cm ; H-NMR: δ 2.8 (t, 2H, -O-CH -CH ), 4.3 (t, 2H,
2
2
-O-CH -CH -), 6.7 - 7.7 (m, 8H, aromatic), 8.27 (s, 1H, -b
CH=N); ms: m/z 299 (M ), 264 (M -Cl), 263 (M -Cl-H). UV-
2
2
+
+
+
General Procedure for the Synthesis of Aldimines 2a-e.
Vis: λ (methanol) (logε)/nm 206 (3.00), 247 (2.46) and 426
max
To a solution of heterocyclic β-chloroaldehydes [9-12] 1a-e (5
mmoles) in absolute ethanol (25 ml) was added in small portions
over a 10 minute period 2-aminophenol (5 mmoles) and the
reaction mass was stirred at room temperature for 30 minutes.
The aldimines (2a-e) that formed were collected by filtration
and recrystallized from carbon tetrachloride. The following
compounds were prepared by following the above-mentioned
procedure with the appropriate reactants.
(2.58).
Anal. Calcd. for C
H
ClNO : C, 68.22; H, 4.68; N, 4.68.
2
17 14
Found: C, 67.90; H, 4.93; N, 4.82.
2-[[(5-Chloro-2,3-dihydro-1-benzothiepin-4-yl)methylene]-
amino]phenol (2e).
This compound was obtained from 5-chloro-2,3-dihydro-1-
benzothiepin-4-carboxaldehyde (1e), (1.12 g, 5 mmoles) and 2
aminophenol (0.54 g, 5 mmoles). Recrystallization of the crude
product from carbon tetrachloride gave a dark orange solid (1.26
2-[[(3-Chloro-6-methoxy-2-benzofuranyl)methylene]amino]-
phenol (2a).
-1
g, 80%), mp 162-164°; ir: ν OH 3460, ν CN 1630, 1400 cm ;
1
H-NMR: δ 2.92 (t, 2H, -S-CH -CH ), 3.52 (t, 2H, -S-CH -
This compound was obtained from 3-chloro-6-methoxybenzo-
furan-2-carboxaldehyde (1a), (1.05 g, 5 mmoles) and 2
aminophenol (0.54 g, 5 mmoles). Recrystallization of the crude
product from carbon tetrachloride gave a yellow crystalline solid
2
2
2
CH ), 6.72 - 7.90 (m, 8H, aromatic), 9.64 (s, 1H, -CH=N-); ms:
m/z 315 (M ), 280 (M -Cl), 279 (M -Cl-H). UV-Vis: λ
(methanol) (logε)/nm 206 (3.03), 253 (2.44) and 424 (2.45).
2
+
+
+
max

Mar-Apr 2001
Studies on the Reactivity of New Types of Tetracyclic-1,5-Benzoxazepines
385
Anal. Calcd. for C
H
ClNO : C, 64.76; H, 4.44; N, 4.44.
Anal. Calcd. for C H NO : C, 77.56; H, 4.94; N, 5.32.
17 13 2
17 14
2
Found: C, 64.56; H, 4.22; N, 4.25.
Found: C, 77.23; H, 4.66; N, 5.10.
Synthesis of Tetracyclic-1,5-benzoxazepines 3a-e.
6,7-Dihydro[1]benzothiepino[5,4-b][1,5]benzoxazepine (3e).
A solution of the aldimine 2a-e (5 mmoles) in dry dimethyl-
formamide (50 ml) was refluxed for 8 hours, after which the
dimethylformamide was removed using a rotary evaporator. The
residue was dissolved in ethyl acetate, washed with water, until
the water layer became colorless. The organic phase was sepa-
rated and dried. Evaporation of the dried organic extract gave a
solid which was chromatographed on a column of silica (1:40).
Elution with hexane/ethylacetate (9:1) afforded the titled
compounds 3a-e in a pure state.
This compound was obtained from 2-[[(5-chloro-2,3-
dihydro-1-benzothiepin-4-yl)methylene]amino]phenol (2e) (1.6
g, 5 mmoles). The crude product was purified by column
chromatography which gave a white crystalline solid (0.767 g,
-1
1
55%) as, mp 182-184°; ir: ν 1630, 1570, 1470 cm ; H-NMR:
3.0 (t, 2H, -S-CH -CH -), 3.4 (t, 2H, -S-CH -CH -), 7.2 - 8.0 (m,
2
2
2
2
+
+
+
9H, aromatic); ms: m/z 279 (M ), 278 (M -H), 252 (M -H-CN).
UV-Vis: λ (methanol) (logε)/nm 207 (3.23) and 261 (3.20).
max
Anal. Calcd. for C
H NOS: C, 73.11; H, 4.65; N, 5.01.
17 13
Found: C, 73.00; H, 4.70; N, 4.89.
3-Methoxybenzofuro[3,2-b][1,5]benzoxazepine (3a).
Procedure for the Preparation of Acetoxy Derivatives 6a-e.
This compound was obtained from 2-[[(3-chloro-6-methoxy-
2-benzofuranyl)methylene]amino]phenol (2a), (1.05 g, 5
mmoles). The crude product was purified by column chromato-
graphy which gave a pale yellow solid (0.53 g, 40%), mp 130-
A well stirred solution of the tetracyclic-1,5-benzoxazepine
3a-e (5 mmoles) in glacial acetic acid (25 ml) and acetic anhy-
dride (0.5 g) was hydrogenated (110 ml hydrogen) using 10%
palladium on activated carbon (100 mg) at atmospheric pres-
sure. After stirring for 4 hours, the solid that was precipitated
out was filtered, washed with water and dried. The impure solid
was chromatographed on silica gel (1:40). Elution with
hexane/ethyl acetate (9:1) gave pure samples of 6a-e.
-1
1
132°; ir: ν CN 1630, 1500, 1260 cm ; H-NMR: δ 3.9 (s, 3H,
+
Ar-OMe), 7.0 - 8.02 (m, 8H, aromatic); ms: m/z 265 (M ), 250
+
+
(M -CH ), 222 (M -CH CO). UV-Vis: λ (methanol)
3
3
max
(logε)/nm 219 (2.99), 241 (2.73), 276 (3.04), 303 (2.52) and 347
(2.78).
Anal. Calcd. for C
Found: C, 72.10; H, 4.56; N, 5.10.
H NO : C, 72.45; H, 4.15; N, 5.28.
16 11 3
2-[[(6-Methoxy-2-benzofuranyl)methylene]amino]phenolacetate
(6a).
6H-[1]Benzopyrano[4,3-b][1,5]benzoxazepine (3b).
This compound was obtained from 3-methoxybenzofuro-
[3,2-b][1, 5]benzoxazepine (3a) (1.32 g, 5 mmoles) by
hydrogenolysis. The crude product was purified by column
chromatography which gave a light yellow solid (0.77 g, 50%),
This compound was obtained from 2-[[(4-chloro-2H-1-
benzopyran-3-yl)methylene]amino]phenol (2b), (1.45 g, 5
mmoles). The crude product was purified by column chromato-
graphy which gave a white crystalline solid (0.622 g, 50%), mp
-1
1
mp 146-148°; ir: ν CO 1750, ν CN 1630, 1260 cm ; H-NMR:
-1
1
δ 2.7 (s, 3H, -OCOMe), 3.9 (s, 3H, Ar-OMe), 6.8 - 8.3 (m, 9H,
130-132°; ir: ν CN 1630, 1560, 1420 cm ; H-NMR: δ 5.29 (s,
+
+
+
aromatic); ms: m/z 309 (M , absent), 266 (M -CH CO), 265
2H, -O-CH -), 6.87 - 8.41 (m, 8H, aromatic); ms: m/z 249 (M ),
3
2
+
+
+
+
(M -CH CO-H).
248 (M -H), 232 (M -OH), 222 (M -HCN). UV-Vis: λ
3
max
(methanol) (logε)/nm 206 (2.82), 244 (2.73) and 273 (2.56), 321
Anal. Calcd. for C H NO : C, 69.90; H, 4.85; N, 4.53.
18 15 4
(2.55) and 394 (2.51).
Found: C, 69.72; H, 4.63; N, 4.29.
Anal. Calcd. for C
Found: C, 76.87; H, 4.66; N, 5.48.
H NO : C, 77.10; H, 4.41; N, 5.62.
16 11 2
2-[[(2H-1-Benzopyran-3-yl)methylene]amino]phenolacetate (6b).
This compound was obtained from 6H-[1]benzopyrano-
[4,3-b][1,5]benzoxazepine (3b) (1.25 g, 5 mmoles) by
hydrogenolysis. The crude product was purified by column
chromatography which gave a white crystalline solid (0.879 g,
6H-[1]Benzothiopyrano[4,3-b][1,5]benzoxazepine (3c).
This compound was obtained from 2-[[(4-chloro-2H-1-
benzothiopyran-3-yl)methylene]amino]phenol (2c), (1.5 g, 5
mmoles). The crude product was purified by column chromato-
graphy which gave a light yellow crystalline solid (0.68 g, 52%),
-1
60%), mp 180-182°; ir: ν CO 1750, ν CN 1630, 1480 cm ;
1
H-NMR: δ 2.66 (s, 3H, -OCOMe), 5.31 (s, 2H, -OCH ),
2
-1
1
+
mp 158-160°; ir: ν CN 1630, 1560, 1480 cm ; H-NMR: δ 4.13
6.82 - 8.45 (m, 10H, aromatic); ms: m/z 293 (M , absent), 251
(M -CH CO), 250 (M -CH CO-H).
+
+
(s, 2H, -S-CH -), 7.40 - 8.81 (m, 9H, aromatic); ms: m/z 265
2
2
2
+
+
+
(M ), 264 (M -H), 236 (M -H-CO). UV-Vis: λ
(methanol)
Anal. Calcd. for C H NO : C, 73.72; H, 5.11; N, 4.77.
max
18 15 3
(logε)/nm 207 (3.03), 263 (3.07) and 277 (2.96) and 348 (2.35).
Found: C, 74.15; H, 5.52; N, 4.57.
Anal. Calcd. for C NOS: C, 72.45; H, 4.15; N, 5.28.
H
16 11
2-[[(2H-1-Benzothiopyran-3-yl)methylene]amino]phenolacetate
(6c).
Found: C, 72.18; H, 4.09; N, 5.01.
6,7-Dihydro[1]benzoxepino[5,4-b][1,5]benzoxazepine (3d).
This compound was obtained from 6H-[1]benzothio-
pyrano[4,3-b][1,5]benzoxazepine (3c) (1.33 g, 5 mmoles) by
hydrogenolysis. The crude product was purified by column
chromatography which gave a white crystalline solid (0.81 g,
This compound was obtained from 2-[[(5-chloro-2,3-
dihydro-1-benzoxepin-4-yl)methylene]amino]phenol (2d) (1.5
g, 5 mmoles). The crude product was purified by column
chromatography which gave a light yellow crystalline solid
-1
53%), mp 198-200°; ir: ν CO 1750, ν CN 1630, 1420 cm ;
1
-1
H-NMR: δ 2.8 (s, 3H, -OCOMe), 4.0 (s, 2H, -SCH -), 7.0 - 8.3
(0.78 g, 60%), mp 220-222°; ir: ν CN 1630, 1560, 1480 cm ;
2
+
1
(m, 10H, aromatic); ms: m/z 309 (M , absent), 267
(M -CH CO), 266 (M -CH CO-H).
H-NMR: δ 3.0 (t, 2H, -O-CH -CH -), 4.6 (t, 2H, -O-CH -
2
2
2
+
+
+
CH -), 7.2 - 8.0 (m, 9H, aromatic); ms: m/z 263 (M ), 262
(M -H), 234 (M -H-CO). UV-Vis: λ
207 (3.26), 266 (3.28) and 318 (2.29).
2
2
2
+
+
Anal. Calcd. for C
H
NO S: C, 69.90; H, 4.85; N, 4.53.
(methanol) (logε)/nm
18 15
2
max
Found: C, 69.49; H, 4.97; N, 4.32.

Vol. 38
B. C. Sekhar, D. V. Ramana, and S. R. Ramadas
386
2-[[(2,3-Dihydro-1-benzoxepin-4-yl)methylene]amino]phenol-
2-[[(2H-1-Benzothiopyran-3-yl)methylene]amino]phenol (7c).
acetate (6d).
This compound was obtained from 2-[[(2H-1-benzothiopyran-
3-yl)methylene]amino]phenolacetate (6c) (1.55 g, 5 mmoles).
The crude product was purified by column chromatography
This compound was obtained from 6,7-dihydro[1]benzoxe-
pino[5,4-b][1,5]benzoxazepine (3d) (1.32 g, 5 mmoles) by
hydrogenolysis. The crude product was purified by column
chromatography which gave a white crystalline solid (0.92 g,
which gave a white crystalline solid (0.56 g, 42%), mp
-1
156-158°; ir: ν OH 3350, ν CN 1630, 1566, 1480 cm
;
-1
1
60%), mp 192-194°; ir: ν CO 1760, ν CN 1630, 1360 cm ;
H-NMR: δ 4.0 (s, 2H, -SCH ), 7.0 - 8.5 (m, 10H, aromatic);
ms: m/z 267 (M ), 266 (M -H), 265 (M -H-H).
Anal. Calcd. for C NOS: C, 71.91; H, 4.86; N, 5.24.
2
1
+
+
+
H-NMR: δ 2.5 (s, 3H, -OCOMe), 3.02 (t, 2H, -OCH -CH ),
2
2
4.58 (t, 2H, -OCH -CH ), 7.0 - 8.3 (m, 10H, aromatic); ms: m/z
307 (M , absent), 265 (M -CH CO), 264 (M -CH CO-H).
H
16 13
2
2
+
+
+
Found: C, 72.11; H, 4.48; N, 5.01.
2
2
Anal. Calcd. for C
Found: C, 74.01; H, 5.35; N, 4.28.
H NO : C, 74.26; H, 5.53; N, 4.56.
19 17 3
2-[[(2,3-Dihydro-1-benzoxepin-4-yl)methylene]amino]phenol (7d).
This compound was obtained from 2-[[(2,3-dihydro-1-
benzoxepin-4-yl)methylene]amino]phenolacetate (6d) (1.55 g, 5
mmoles). The crude product was purified by column chromato-
2-[[(2,3-Dihydro-1-benzothiepin-4-yl)methylene]amino]phenol-
acetate (6e).
This compound was obtained from 6,7-dihydro[1]benzo-
thiepino[5,4-b][1,5]benzoxazepine (3e) (1.6 g, 5 mmoles). The
crude product was purified by column chromatography which
gave a white crystalline solid (1.21 g, 75%), mp 186-188°; ir: ν
graphy which gave a white crystalline solid (0.66 g, 50%), mp
-1
156-158°; ir: ν OH 3350, ν CN 1630, 1570, 1400 cm
;
1
H-NMR: δ 3.04 (t, 2H, -OCH -CH ), 4.66 (t, 2H, -OCH CH ),
2
2
2
2
+
+
7.01 - 8.04 (m, 10H, aromatic); ms: m/z 265 (M ), 264 (M -H),
-1
1
+
CO 1760, ν CN 1630, 1360 cm ; H-NMR: δ 2.5 (s, 3H,
263 (M -H-H).
-OCOMe), 3.02 (t, 2H, -OCH -CH ), 4.58 (t, 2H, OCH -CH ),
Anal. Calcd. for C
H NO : C, 76.98; H, 5.66; N, 5.28.
17 15 2
2
2
2
2
+
7.72 - 8.04 (m, 10H, aromatic); ms: m/z 323 (M , absent), 281
(M -CH CO), 280 (M -CH CO-H).
Found: C, 76.59; H, 5.21; N, 5.08.
+
+
2
2
2-[[(2,3-Dihydro-1-benzthiepin-4-yl)methylene]amino]phenol (7e).
Anal. Calcd. for C
H NO : C, 70.58; H, 5.26; N, 4.33.
19 17 3
This compound was obtained from 2-[[(2,3-dihydro-1-
benzothiepin-4-yl)methylene]amino]phenolacetate (6e) (1.61 g, 5
mmoles). The crude product was purified by column chromato-
graphy which gave a white crystalline solid (0.77 g, 55%), mp
Found: C, 70.72; H, 5.35; N, 4.21.
Procedure for the Preparation of Phenol Derivatives 7a-e.
A solution of the acetoxy derivative 6a-e (5 mmoles) in 10%
ethanolic KOH (10 ml) was refluxed for 30 minutes and the
solvent was evaporated by rotary evaporator under vacuum. The
resulting mixture was cooled and dissolved in ethyl acetate. The
organic layer was washed with water till the pH becomes
neutral. The organic phase was dried and evaporated to give a
solid residue, which was chromatographed on a column of silica
(1:40). Elution with hexane/ethylacetate (9:1) gave pure samples
of 7a-e.
-1
1
86 - 88°; ir: ν OH 3460, ν CN 1630, 1570 cm ; H-NMR: 2.91
(t, 2H, -SCH -CH ), 3.35 (t, 2H, -SCH -CH ), 7.03 - 8.16 (m,
2
2
2
2
+
+
+
10H, aromatic); ms: m/z 281 (M ), 280 (M -H), 279 (M -H-H).
Anal. Calcd. for C NOS: C, 72.59; H, 5.33; N, 4.98.
H
17 15
Found: C, 72.23; H, 5.41; N, 4.72.
REFERENCES AND NOTES
2-[[(6-Methoxy-2-benzofuranyl)methylene]amino]phenol (7a).
[1] E. F. Nielsen and E. B. Pedersen, Chem. Scr., 26, 343, (1986).
[2] N. Bhanumathi, K. R. Rao and P. B. Sattur, Heterocycles, 24,
This compound was obtained from 2-[[(6-methoxy-2-benzo-
furanyl)methylene]amino]phenolacetate (6a) (1.54 g, 5
mmoles). The crude product was purified by column chromato-
graphy which gave a white crystalline solid (0.534 g, 40%), mp
1683, (1986).
[3] G. P. Zecchini, I. Torrini and M. P. Paradisi, Heterocycles,
26, 2443, (1987).
[4] I. Torrini, G. P. Zecchini and M. P. Paradisi, Heterocycles,
27, 401, (1988).
[5] G. P. Zecchini, M. P. Paradisi and F. Scazzocchio,
Heterocycles, 31, 1687, (1990).
[6] G. R. Rao and K. R. Srinivasa, Indian J. Pharm. Sci., 53,
37, (1991).
-1
1
126-128°; ir: ν OH 3450, ν CN 1640, 1240 cm ; H-NMR: δ
3.9 (s, 3H, Ar-OMe), 6.80 - 8.30 (m, 9H, aromatic); ms: m/z 267
+
+
+
(M , absent), 266 (M -H), 265 (M -H-H).
Anal. Calcd. for C NO : C, 71.91; H, 4.86; N, 5.24.
H
16 13
3
Found: C, 71.62; H, 4.59; N, 5.01.
[7] A. Jaya Shree and M. Darbarwar, Org. Prep. Proced. Int., 25,
65, (1993).
2-[[(2H-1-Benzopyran-3-yl)methylene]amino]phenol (7b).
[8] N. J. Holman and G. B. Tometzki, WO 98,05,657 (1998);
Chem. Abstr., 128, 16745a (1998).
[9] B. Chandra Sekhar, D. V. Ramana and S. R. Ramadas, Sulfur
Lett., 6, 149, (1987).
[10] B. Chandra Sekhar, D. V. Ramana and S. R. Ramadas, Sulfur
Lett., 9, 271, (1989).
[11] B. Chandra Sekhar, D. V. Ramana and S. R. Ramadas, Sulfur
Lett., 10, 149, (1989).
This compound was obtained from 2-[[(2H-1-benzopyran-3-
yl)methylene]amino]phenolacetate (6b) (1.47 g, 5 mmoles). The
crude product was purified by column chromatography which
gave a white crystalline solid (0.50 g, 40%), mp 126-128°; ir: ν
-1
1
OH 3350, ν CN 1620, 1400 cm ; H-NMR: δ 5.17 (s, 2H,
+
-OCH ), 6.77 - 8.45 (m, 10H, aromatic); ms: m/z 251 (M ), 250
2
+
+
(M -H), 249 (M -H-H).
Anal. Calcd. for C
Found: C, 76.82; H, 4.93; N, 5.28.
H NO : C, 76.49; H, 5.17; N, 5.57.
[12] B. Chandra Sekhar, D. V. Ramana and S. R. Ramadas, J.
Indian. Chem. Soc., 67, 493, (1990).
16 13 2