2212
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
Sosnovskikh et al.
Scheme 3
2ꢀ(2ꢀHydroxyꢀ5ꢀmethylphenyl)ꢀ7,7ꢀdimethylꢀ7,8ꢀdihydroꢀ
quinolinꢀ5(6H)ꢀone (8b) was obtained similarly to compound
8a from chromone 1b in 25% yield as colorless crystals with
m.p. 193—194 °C. Found (%): C, 76.64; H, 6.74; N, 4.87.
C18H19NO2. Calculated (%): C, 76.84; H, 6.81; N, 4.98.
IR, ν/cm–1: 1686, 1618, 1582, 1563, 1492, 1455. 1H NMR
(DMSOꢀd6), δ: 1.07 (s, 6 H, 2 Me); 2.30 (s, 3 H, Me); 2.60 (s,
2 H, C(6)H2); 3.08 (s, 2 H, C(8)H2); 6.87 (d, 1 H, H(3´),
Jo = 8.3 Hz); 7.20 (dd, 1 H, H(4´), Jo = 8.3 Hz, Jm = 1.8 Hz);
7.89 (d, 1 H, H(6´), Jm = 1.8 Hz); 8.21 (d, 1 H, H(3), Jo = 8.6 Hz);
8.30 (d, 1 H, H(4), Jo = 8.6 Hz); 13.72 (s, 1 H, OH).
7,7ꢀDimethylꢀ3ꢀsalicylꢀ7,8ꢀdihydroquinolinꢀ5(6H)ꢀone (9a).
A solution of chromone 2a (1.0 g, 5.7 mmol), dimedone (2.0 g,
14.4 mmol), and ammonium acetate (6.3 g, 82.0 mmol) in
ethanol (35 mL) was refluxed for 2 h. Then, the solution was half
concentrated and cooled, the crystals formed were filtered off,
dried, and recrystallized from aqueous ethanol (1 : 1) to obtain
compound 9a (1.0 g, 59%) as colorless crystals with m.p. 132—
133 °C. Found (%): C, 73.42; H, 5.60; N, 4.61. C18H17NO3.
Calculated (%): C, 73.20; H, 5.80; N, 4.74. IR, ν/cm–1: 3457,
1
1691, 1625, 1590, 1484, 1463. H NMR (CDCl3), δ: 1.17 (s,
6 H, 2 Me); 2.63 (s, 2 H, C(6)H2); 3.15 (s, 2 H, C(8)H2); 6.92
(ddd, 1 H, H(5´), Jo = 8.0 Hz, Jo = 7.3 Hz, Jm = 1.1 Hz); 7.11
(dd, 1 H, H(3´), Jo = 8.5 Hz, Jm = 1.1 Hz); 7.51 (dd, 1 H, H(6´),
Jo = 8.0 Hz, Jm = 1.6 Hz); 7.56 (ddd, 1 H, H(4´), Jo = 8.5 Hz,
Jo = 7.3 Hz, Jm = 1.6 Hz); 8.54 (d, 1 H, H(4), Jm = 2.3 Hz); 9.01
(d, 1 H, H(2), Jm = 2.3 Hz); 11.80 (s, 1 H, OH).
1
IR spectroscopy, as well as H NMR spectroscopy. In
the 1H NMR spectra of these compounds, along with the
signals for aliphatic and benzene protons there are two
doublets for the pyridine protons H(3) and H(4) at δ 8.2 and
8.3 with Jo = 8.6 Hz for 8a,b, two doublets for the protons
H(4) and H(2) at δ 8.5 and 9.0 with Jm = 2.3 Hz for 9a—c
and 10, and a singlet for the H(11) at δ 8.9 for 11a,b.
In conclusion, a direction of threeꢀcomponent conꢀ
densation of 3ꢀsubstituted chromones with dimedone and
ammonium acetate is defined by the nature of the subꢀ
stituent at position 3 and leads to the synthesis of new
derivatives of partially hydrogenated quinoline.
3ꢀ(2ꢀHydroxyꢀ5ꢀmethylbenzoyl)ꢀ7,7ꢀdimethylꢀ7,8ꢀdihydroꢀ
quinolinꢀ5(6H)ꢀone (9b) was obtained similarly to compound
9a from chromone 2b in 34% yield as colorless crystals with
m.p. 164—165 °C. Found (%): C, 73.46; H, 6.22; N, 4.36.
C19H19NO3. Calculated (%): C, 73.77; H, 6.19; N, 4.53. IR,
1
ν/cm–1: 3178, 1681, 1638, 1613, 1590, 1480, 1461. H NMR
(CDCl3), δ: 1.17 (s, 6 H, 2 Me); 2.27 (s, 3 H, Me); 2.63 (s, 2 H,
C(6)H2); 3.16 (s, 2 H, C(8)H2); 7.01 (d, 1 H, H(3´), Jo = 8.5 Hz);
7.26 (br.s, 1 H, H(6´), Jm = 1.5 Hz); 7.38 (dd, 1 H, H(4´),
Jo = 8.5 Hz, Jm = 2.1 Hz); 8.54 (d, 1 H, H(4), Jm = 2.3 Hz); 8.99
(d, 1 H, H(2), Jm = 2.3 Hz); 11.62 (s, 1 H, OH).
Experimental
3ꢀ(5ꢀChloroꢀ2ꢀhydroxybenzoyl)ꢀ7,7ꢀdimethylꢀ7,8ꢀdihydroꢀ
quinolinꢀ5(6H)ꢀone (9c) was obtained similarly to compound
9a from chromone 2c in 57% yield as colorless crystals with
m.p. 160—161 °C. Found (%): C, 65.59; H, 4.81; N, 4.24.
C18H16ClNO3. Calculated (%): C, 65.56; H, 4.89; N, 4.25.
IR, ν/cm–1: 3445, 1684, 1633, 1613, 1592, 1570, 1551, 1457.
1H NMR (CDCl3), δ: 1.18 (s, 6 H, 2 Me); 2.64 (s, 2 H, C(6)H2);
3.17 (s, 2 H, C(8)H2); 7.08 (d, 1 H, H(3´), Jo = 8.9 Hz); 7.46
(d, 1 H, H(6´), Jm = 2.6 Hz); 7.51 (dd, 1 H, H(4´), Jo = 8.9 Hz,
Jm = 2.6 Hz); 8.54 (d, 1 H, H(4), Jm = 2.3 Hz); 8.99 (d, 1 H,
H(2), Jm = 2.3 Hz); 11.68 (s, 1 H, OH).
7,7ꢀDimethylꢀ5ꢀoxoꢀ5,6,7,8ꢀtetrahydroquinolineꢀ3ꢀcarꢀ
boxylic acid (10) was obtained from pyridine 9a according to the
procedure described in Ref. 7. The yield was 50%, colorless
crystals with m.p. 215—216 °C. Found (%): C, 66.08; H, 6.20;
N, 6.12. C12H13NO3. Calculated (%): C, 65.74; H, 5.98; N,
6.39. IR, ν/cm–1: 2460, 1703, 1689, 1603, 1563, 1575, 1465.
1H NMR (DMSOꢀd6), δ: 1.04 (s, 6 H, 2 Me); 2.62 (s, 2 H,
C(6)H2); 3.09 (s, 2 H, C(8)H2); 8.54 (d, 1 H, H(4), Jm = 2.2 Hz);
9.17 (d, 1 H, H(2), Jm = 2.2 Hz); 13.4—13.8 (br.s, 1 H, OH).
8,8ꢀDimethylꢀ8Hꢀchromeno[2,3ꢀb]quinolineꢀ10,12(7H,9H)ꢀ
dione (11a). A solution of chromone 3a (200 mg, 1.2 mmol),
dimedone (410 mg, 2.9 mmol), and ammonium acetate (1.3 g,
IR spectra were recorded on a PerkinꢀElmer Spectrum BXꢀII
spectrometer in KBr pellets. 1H NMR spectra were recorded
on a Bruker DRXꢀ400 spectrometer in DMSOꢀd6 or CDCl3
(400.1 MHz, internal standard, Me4Si). Chromones 1—3 and
12 were obtained according to procedures described earlier.8,12,13
2ꢀ(2ꢀHydroxyphenyl)ꢀ7,7ꢀdimethylꢀ7,8ꢀdihydroquinolinꢀ
5(6H)ꢀone (8a). A solution of chromone 1a (250 mg, 1.0 mmol),
dimedone (360 mg, 2.6 mmol), and ammonium acetate (1.1 g,
14.3 mmol) in ethanol (5 mL) was refluxed for 4 h. Then, the
reaction mixture was concentrated to dryness and the residue
was recrystallized from methanol to obtain compound 8a (60 mg,
23%) as colorless crystals with m.p. 142—143 °C. Found (%): C,
76.23; H, 6.47; N, 5.34. C17H17NO2. Calculated (%): C, 76.38;
H, 6.41; N, 5.24. IR, ν/cm–1: 1686, 1585, 1562, 1507, 1472.
1H NMR (DMSOꢀd6), δ: 1.08 (s, 6 H, 2 Me); 2.60 (s, 2 H,
C(6)H2); 3.09 (s, 2 H, C(8)H2); 6.94—6.98 (m, 2 H, H(3´),
H(5´)); 7.39 (ddd, 1 H, H(4´), Jo = 8.3 Hz, Jo = 7.2 Hz, Jm = 1.6 Hz);
8.08 (dd, 1 H, H(6´), Jo = 8.5 Hz, Jm = 1.6 Hz); 8.22 (d, 1 H, H(3),
Jo = 8.6 Hz); 8.31 (d, 1 H, H(4), Jo = 8.6 Hz); 13.98 (s, 1 H, OH).
Compound 8a was also obtained by alternative synthesis
from unsubstituted chromone, dimedone, and ammonium
acetate under similar conditions in 7% yield.