Reactions of β-aroylacrylic acids with 2-aminophenols

Article abstract of DOI:10.1007/s11172-006-0376-y

3,4-Dihydrobenzo-1,4-oxazin-2-ones were obtained from the corresponding β-aroylacrylic acids and 2-aminophenols. With 2-amino-4(5)-nitrophenols, stable intermediate β-amino adducts (4-aryl-4-oxobutyric acid derivatives) were isolated.

Full text of DOI:10.1007/s11172-006-0376-y

Russian Chemical Bulletin, International Edition, Vol. 55, No. 6, pp. 1056—1059, June, 2006
1056
Reactions of βꢀaroylacrylic acids with 2ꢀaminophenols
T. V. Beryozkina,a N. N. Kolos,a V. I. Musatov,b and V. D. Orlova
ꢀ
aV. N. Karazin Kharkov National University,
4 pl. Svobody, 61077 Kharkov, Ukraine.
Eꢀmail: orlov@univer.kharkov.ua
bScientific and Technological Corporation "Institute for Single Crystals", National Academy of Sciences of Ukraine,
60 prosp. Lenina, 61001 Kharkov, Ukraine.
Eꢀmail: musatov@isc.kharkov.com
3,4ꢀDihydrobenzoꢀ1,4ꢀoxazinꢀ2ꢀones were obtained from the corresponding βꢀaroylacrylic
acids and 2ꢀaminophenols. With 2ꢀaminoꢀ4(5)ꢀnitrophenols, stable intermediate αꢀamino
adducts (4ꢀarylꢀ4ꢀoxobutyric acid derivatives) were isolated.
Key words: βꢀaroylacrylic acids, 2ꢀaminophenols, 3,4ꢀdihydrobenzoꢀ1,4ꢀoxazinꢀ2ꢀones,
cyclization, 4ꢀarylꢀ4ꢀoxobutyric acids.
Reactions of α,βꢀunsaturated carbonyl compounds
with binucleophiles provide a convenient route to parꢀ
tially hydrogenated azaheterocycles. Earlier, we have
found that reactions of chalcones with oꢀphenylenediꢀ
amine1 and 2ꢀaminobenzenethiol2,3 give 1,5ꢀbenzodiꢀ
azepines 1 and 1,5ꢀbenzothiazepines 2, respectively, while
reactions with 2ꢀaminophenol4 yield phenoxazines 3.
benzenethiol12 to give benzoꢀ1,4ꢀthiazinꢀ3ꢀones 5
(not 1,5ꢀbenzothiazepines, as erroneously reported in
Refs 13—17).
Here, we studied the reactions of acids 6a—d with
2ꢀaminophenol (7a) and its substituted derivatives 7b—e
(Scheme 1).
Heating of 2ꢀaminophenols 7a—c with acids 6a—d in
boiling propanꢀ2ꢀol or toluene gave 3ꢀ(2ꢀarylꢀ2ꢀoxoꢀ
ethyl)ꢀ3,4ꢀdihydrobenzoꢀ1,4ꢀoxazinꢀ2ꢀones 8a—f in
33—48% yields.
Compound 8a has been obtained earlier18 (m.p.
180 °C) by reduction of the corresponding benzoꢀ
1,4ꢀoxazinꢀ2ꢀone. Product 8a we synthesized melts at
129—131 °C, which agrees better with both the melting
points of compounds 8b—d and the reported18 melting
points of 3,4ꢀdihydrobenzoꢀ1,4ꢀoxazinꢀ2ꢀone derivatives.
Reactions of acids 6a—c with 2ꢀaminoꢀ4(5)ꢀnitroꢀ
phenols 7d,e under the same conditions followed a differꢀ
ent scheme. Yellowꢀorange crystalline solids 9a—d isoꢀ
lated from the reaction mixture in 35—54% yields deꢀ
compose on melting, are well soluble in polar solvents,
give a positive test for the phenol OH group, and are
soluble in alkaline solution.
Our further investigations of the reactivities of enone
systems deal with βꢀaroylacrylic acids. Although the chemꢀ
istry of these acids has been studied for a sufficiently long
time, data on their reactions with nitrogenꢀcontaining
1,4ꢀbinucleophiles remain limited. At the same time,
βꢀaroylacrylic acid derivatives exhibit a broad spectrum of
physiological (fungicidal, antitumor, hypotensive, hypoꢀ
lipedemic, etc.) activity,4—10 which makes their reactions
with 1,4ꢀbinucleophiles a subject of current interest for
the synthesis of azaheterocycles.
Earlier, we have found that βꢀaroylacrylic acids unꢀ
dergo cyclocondensation in reactions with oꢀphenyleneꢀ
diamine11 to give quinoxalinꢀ2ꢀones 4 and with oꢀaminoꢀ
Attempted cyclization of products 9a—d by heating
them in boiling ethanol, propanꢀ2ꢀol, butanol, or toluene
without and with addition of conc. HCl, as well as in
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1018—1021, June, 2006.
1066ꢀ5285/06/5506ꢀ1056 © 2006 Springer Science+Business Media, Inc.

4HꢀBenzoꢀ1,4ꢀoxazinꢀ2ꢀones
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
1057
Scheme 1
6
Ar
7
R
8
Ar
R
8
Ar
R
9
Ar
R
a
b
c
d
Ph
a
b
c
d
e
H
Me
Cl
4ꢀNO2
5ꢀNO2
a
b
c
d
Ph
H
H
H
H
e
f
g
h
4ꢀBrC6H4
4ꢀBrC6H4
Ph
6ꢀMe
6ꢀCl
7ꢀNO2
7ꢀNO2
a
b
c
d
Ph
Ph
5ꢀNO2
4ꢀNO2
4ꢀNO2
4ꢀNO2
4ꢀMeC6H4
4ꢀClC6H4
4ꢀBrC6H4
4ꢀMeC6H4
4ꢀClC6H4
4ꢀBrC6H4
4ꢀMeC6H4
4ꢀClC6H4
4ꢀMeC6H4
129—131 °C. Found (%): C, 71.94; H, 4.91; N, 5.20.
glacial acetic acid, failed: the starting reagents contamiꢀ
nated with resins were recovered from the reaction mixꢀ
ture. Yet the cyclization was successful for αꢀadducts 9b,c:
their heating in boiling trifluoroacetic acid afforded
benzooxazines 8g (43%) and 8h (41%).
C16H13NO3. Calculated (%): C, 71.94; H, 4.90; N, 5.24. IR,
1
ν/cm–1: 1698 (C(2)=O); 1668 (PhCO). H NMR, δ: 3.65 (d,
2 H, CH2, J = 5.4 Hz); 5.07 (t, 1 H, H(3), J = 5.4 Hz); 6.84—6.91
(m, 4 H, H arom.); 7.49—7.69 (m, 3 H, H arom.); 7.96—7.99
(m, 2 H, H arom.); 10.65 (s, 1 H, NH).
Interestingly, analogous reactions of aroylpyruvic acꢀ
ids and their esters with both 2ꢀaminoꢀ4ꢀnitrophenol19
and 2ꢀaminophenol20—23 give exclusively cyclic products.
The observed different behavior of aminophenols 7a—e
is due to a considerable electronꢀwithdrawing effect of
the nitro group. As the result, the hydroxy group becomes
substantially less nucleophilic, which hinders esterificaꢀ
tion and makes it possible to isolate αꢀadducts 9a—d.
Compounds 8b—f were obtained analogously but with
propanꢀ2ꢀol as a solvent.
3ꢀ(2ꢀOxoꢀ2ꢀpꢀtolylethyl)ꢀ3,4ꢀdihydrobenzoꢀ1,4ꢀoxazinꢀ2ꢀ
one (8b). The yield was 0.16 g (38%), m.p. 164 °C (from ethaꢀ
nol). Found (%): C, 72.81; H, 5.35; N, 5.01. C17H15NO3. Calꢀ
culated (%): C, 72.85; H, 5.37; N, 4.98. IR, ν/cm–1: 1692
1
(C(2)=O); 1662 (ArCO). H NMR, δ: 2.37 (s, 3 H, Me); 3.62
(d, 2 H, CH2, J = 5.0 Hz); 5.06 (t, 1 H, H(3), J = 5.0 Hz);
6.84—6.92 (m, 4 H, H arom.); 7.33, 7.88 (both d, 2 H each,
H arom., J = 8.0 Hz); 10.70 (s, 1 H, NH).
Experimental
3ꢀ[2ꢀ(4ꢀChlorophenyl)ꢀ2ꢀoxoethyl]ꢀ3,4ꢀdihydrobenzoꢀ1,4ꢀ
oxazinꢀ2ꢀone (8c). The yield was 0.15 g (33%), m.p. 140—141 °C
(from ethanol). Found (%): C, 63.67; H, 4.03; N, 4.61.
C16H12ClNO3. Calculated (%): C, 63.69; H, 4.01; N, 4.64. IR,
The course of the reactions was monitored and the purity of
the compounds obtained was checked by TLC on Silufol UVꢀ254
plates in toluene—MeCN (1 : 1) (spots were visualized in the
iodine vapor). IR spectra were recorded on Impactꢀ400 and
Specord 75IR spectrometers (KBr pellets). 1H NMR spectra
were recorded on a Varian Mercury VXꢀ200 instrument in
DMSOꢀd6 with Me4Si as the internal standard. Elemental analyꢀ
sis was carried out on a LECO CHNSꢀ900 analyzer. Melting
points were measured on a Kofler instrument.
βꢀAroylacrylic acids 6a—d were prepared by the
Friedel—Crafts acylation of the corresponding arenes with maꢀ
leic anhydride; their physicochemical properties are in full agreeꢀ
ment with the literature data.24
1
ν/cm–1: 1692 (C(2)=O); 1662 (ArCO). H NMR, δ: 3.68 (d,
2 H, CH2, J = 5.4 Hz); 5.06 (t, 1 H, H(3), J = 5.4 Hz); 6.72—7.00
(m, 4 H, H arom.); 7.00, 7.60 (both d, 2 H each, H arom., J =
8.6 Hz); 10.73 (s, 1 H, NH).
3ꢀ[2ꢀ(4ꢀBromophenyl)ꢀ2ꢀoxoethyl]ꢀ3,4ꢀdihydrobenzoꢀ1,4ꢀ
oxazinꢀ2ꢀone (8d). The yield was 0.19 g (37%), m.p. 179—180 °C
(from ethanol). Found (%): C, 55.52; H, 3.52; N, 4.07.
C16H12BrNO3. Calculated (%): C, 55.51; H, 3.49; N, 4.05. IR,
1
ν/cm–1: 1692 (C(2)=O); 1662 (ArCO). H NMR, δ: 3.66 (d,
2 H, CH2, J = 5.1 Hz); 5.06 (t, 1 H, H(3), J = 5.1 Hz); 6.84—6.91
(m, 4 H, H arom.); 7.74, 7.92 (both d, 2 H each, H arom., J =
8.3 Hz); 10.72 (s, 1 H, NH).
3ꢀ[2ꢀ(4ꢀBromophenyl)ꢀ2ꢀoxoethyl]ꢀ6ꢀmethylꢀ3,4ꢀdihydroꢀ
benzoꢀ1,4ꢀoxazinꢀ2ꢀone (8e). The yield was 0.25 g (48%), m.p.
192—194 °C (from methanol). Found (%): C, 56.66; H, 3.90;
N, 3.86. C17H14BrNO3. Calculated (%): C, 56.69; H, 3.92;
3ꢀ(2ꢀOxoꢀ2ꢀphenylethyl)ꢀ3,4ꢀdihydrobenzoꢀ1,4ꢀoxazinꢀ
2ꢀone (8a). A solution of acid 6a (0.27 g, 1.5 mmol) and
2ꢀaminophenol (7a) (0.16 g, 1.5 mmol) in toluene (6 mL) was
refluxed for 3 h. The resulting precipitate was recrystallized
from ethanol. The yield of compound 8a was 0.17 g (42%), m.p.

1058
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
Beryozkina et al.
1
N, 3.89. IR, ν/cm–1: 1695 (C(2)=O); 1663 (ArCO). H NMR,
δ: 2.20 (s, 3 H, Me); 3.64 (d, 2 H, CH2, J = 5.2 Hz); 5.01 (t, 1 H,
H(3), J = 5.2 Hz); 6.69 (m, 3 H, H arom.); 7.74, 7.93 (both d,
2 H each, H arom., J = 7.7 Hz); 10.68 (s, 1 H, NH).
2ꢀ[(2ꢀHydroxyꢀ4ꢀnitrophenyl)amino]ꢀ4ꢀoxoꢀ4ꢀpꢀtolylbutyric
acid (9c). The yield was 0.36 g (35%), m.p. 146 °C (from benꢀ
zene—methanol (5 : 1)). Found (%): C, 59.34; H, 4.69; N, 8.14.
C17H16N2O6. Calculated (%): C, 59.30; H, 4.68; N, 8.14. IR,
ν/cm–1: 3423 (NH); 3309 (OH); 1729 (COOH); 1682 (ArCO);
1535, 1362 (NO2). 1H NMR, δ: 2.36 (s, 3 H, Me); 3.57 (dd, 1 H,
HA, 2J = 18.0 Hz, 3J = 6.0 Hz); 3.73 (dd, 1 H, HB, 2J = 18.0 Hz,
3J = 4.0 Hz); 4.73 (dd, 1 H, HX, 3J = 6.0 Hz, 3J = 4.0 Hz); 6.18
(d, 1 H, NH, J = 8.0 Hz); 6.69 (d, 1 H, H arom., J = 8.0 Hz);
7.49—7.88 (m, 6 H, H arom.); 10.34 (br.s, 1 H, OH); 12.78
(br.s, 1 H, COOH).
3ꢀ[2ꢀ(4ꢀBromophenyl)ꢀ2ꢀoxoethyl]ꢀ6ꢀchloroꢀ3,4ꢀdihydroꢀ
benzoꢀ1,4ꢀoxazinꢀ2ꢀone (8f). The yield was 0.23 g (41%), m.p.
194—196 °C (from methanol). Found (%): C, 50.51; H, 2.94;
N, 3.67. C16H11BrClNO3. Calculated (%): C, 50.49; H, 2.91;
1
N, 3.68. IR, ν/cm–1: 1695 (C(2)=O); 1665 (ArCO). H NMR,
δ: 3.69 (d, 2 H, CH2, J = 4.0 Hz); 5.12 (t, 1 H, H(3), J =
4.0 Hz); 6.89 (m, 3 H, H arom.); 7.74, 7.91 (both d, 2 H each,
H arom., J = 8.0 Hz); 10.85 (s, 1 H, NH).
4ꢀ(4ꢀChlorophenyl)ꢀ2ꢀ[(2ꢀhydroxyꢀ4ꢀnitrophenyl)amino]ꢀ4ꢀ
oxobutyric acid (9d). The yield was 0.52 g (48%), m.p. 107 °C
(from benzene—methanol (5 : 1)). Found (%): C, 52.73; H, 3.57;
N, 7.66. C16H13ClN2O6. Calculated (%): C, 52.69; H, 3.59;
N, 7.68. IR, ν/cm–1: 3403 (NH); 3310 (OH); 1702 (COOH);
7ꢀNitroꢀ3ꢀ(2ꢀoxoꢀ2ꢀphenylethyl)ꢀ3,4ꢀdihydrobenzoꢀ1,4ꢀ
oxazinꢀ2ꢀone (8g). A solution of compound 9b (0.31 g, 1 mmol)
in trifluoroacetic acid (5 mL) was refluxed for 5 h and then
poured onto ice. The precipitate that formed was filtered off and
recrystallized from methanol. The yield of product 8g was 0.13 g
(43%), m.p. 195 °C (from ethanol). Found (%): C, 61.51;
H, 3.91; N, 8.94. C16H12N2O5. Calculated (%): C, 61.54;
H, 3.87; N, 8.97. IR, ν/cm–1: 1695 (C(2)=O); 1675 (ArCO);
1519, 1369 (NO2). 1H NMR, δ: 3.77 (d, 2 H, CH2, J = 4.5 Hz);
5.28 (t, 1 H, H(3), J = 4.5 Hz); 7.06 (d, 2 H, H arom., J =
8.2 Hz); 7.49—7.70 (m, 4 H, H arom.); 7.89 (m, 1 H, H arom.);
7.99 (d, 2 H, H arom., J = 7.0 Hz); 11.35 (s, 1 H, NH).
Compound 8h was obtained analogously from adduct 9c.
7ꢀNitroꢀ3ꢀ(2ꢀoxoꢀ2ꢀpꢀtolylethyl)ꢀ3,4ꢀdihydrobenzoꢀ1,4ꢀ
oxazinꢀ2ꢀone (8h). The yield was 0.13 g (41%), m.p. 189 °C
(from ethanol). Found (%): C, 62.61; H, 4.29; N, 8.60.
C17H14N2O5. Calculated (%): C, 62.58; H, 4.32; N, 8.58. IR,
ν/cm–1: 1692 (C(2)=O); 1673 (ArCO); 1518, 1369 (NO2).
1H NMR, δ: 2.32 (s, 3 H, Me); 3.75 (d, 2 H, CH2, J = 4.6 Hz);
5.26 (t, 1 H, H(3), J = 4.6 Hz); 7.05 (d, 2 H, H arom., J =
8.1 Hz); 7.22, 7.74 (both d, 2 H each, H arom., J = 8.3 Hz); 7.96
(m, 2 H, H arom.); 11.31 (s, 1 H, NH).
2ꢀ[(2ꢀHydroxyꢀ5ꢀnitrophenyl)amino]ꢀ4ꢀoxoꢀ4ꢀphenylbutyric
acid (9a). A solution of acid 6a (0.53 g, 3 mmol) and
2ꢀaminophenol 7d (0.46 g, 3 mmol) in propanꢀ2ꢀol (15 mL) was
refluxed for 3 h and then concentrated to dryness. The residue
was washed with water (10×15 mL) and dried in air. The resultꢀ
ing semicrystalline substance was triturated with hexane and
recrystallized from benzene—methanol (5 : 1). The yield of prodꢀ
uct 9a was 0.41 g (41%), m.p. 170 °C. Found (%): C, 58.15;
H, 4.29; N, 8.46. C16H14N2O6. Calculated (%): C, 58.18;
H, 4.27; N, 8.48. IR, ν/cm–1: 3423 (NH); 3313 (OH); 1725
1
1682 (PhCO); 1532, 1365 (NO2). H NMR, δ: 3.60 (dd, 1 H,
HA, 2J = 18.0 Hz, 3J = 6.0 Hz); 3.76 (dd, 1 H, HB, 2J = 18.0 Hz,
3J = 4.0 Hz); 4.74 (dd, 1 H, HX, 3J = 6.0 Hz, 3J = 4.0 Hz); 6.20
(d, 1 H, NH, J = 8.0 Hz); 6.69 (d, 1 H, H arom., J = 8.0 Hz);
7.49—7.99 (m, 6 H, H arom.); 10.31 (br.s, 1 H, OH); 12.69
(br.s, 1 H, COOH).
References
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(COOH); 1685 (PhCO); 1535, 1369 (NO2). H NMR, δ: 3.61
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2ꢀ[(2ꢀHydroxyꢀ4ꢀnitrophenyl)amino]ꢀ4ꢀoxoꢀ4ꢀphenylbutyric
acid (9b). The yield was 0.54 g (54%), m.p. 158 °C (from benꢀ
zene—methanol (5 : 1)). Found (%): C, 58.14; H, 4.25; N, 8.50.
C16H14N2O6. Calculated (%): C, 58.18; H, 4.27; N, 8.48. IR,
ν/cm–1: 3423 (NH); 3313 (OH); 1722 (COOH); 1675 (PhCO);
1532, 1369 (NO2). 1H NMR, δ: 3.60 (dd, 1 H, HA, 2J = 18.0 Hz,
3J = 5.8 Hz); 3.77 (dd, 1 H, HB, 2J = 18.0 Hz, 3J = 4.8 Hz); 4.73
3
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4HꢀBenzoꢀ1,4ꢀoxazinꢀ2ꢀones
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
1059
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Received April 6, 2006;
in revised form April 28, 2006