TABLE 2. 1H NMR Spectra of Compounds 2, 4a-c
Com-
1Н NMR spectrum, δ, ppm (J, Hz)
pound
2
2.25 (1H, br. s, NH); 2.45 and 2.61 (2×3Н, 2 s, 7- and 8-Ме); 2.75 (2Н, t, β-Н);
3.25 (3Н, s, ОМе); 3.44 (2Н, t, γ-Н); 3.92 (2Н, s, α-Н); 7.45 (1Н, d, J56 = 10, 5-Н);
7.73 (1Н, d, J65 = 10, 6-Н); 8.34 (1Н, s, 4-Н)
2.43 and 2.62 (2×3Н, 2 s, 8- and 9-Ме); 3.28 (3Н, s, ОМе); 3.70 (2Н, t, β-Н);
3.86 (3Н, s, =N–Me); 4.18 (2Н, t, γ-Н); 4.78 (2Н, s, 4-Н); 7.30 (1Н, d, J76 = 10, 7-Н);
7.61 (1Н, d, J67 = 10, 6-Н); 8.05 (1Н, s, 5-Н)
2.38 and 2.42 (2×3Н, 2 s, 8- and 9-Ме); 3.32 (3Н, s, ОМе); 3.75 (2Н, t, β-Н);
4.25 (2Н, t, γ-Н); 4.87 (2Н, s, 4-Н); 6.12 (2Н, s, СН2Ph); 7.13-7.29 (5Н, m, Ph);
7.34 (1Н, d, J76 = 10, 7-Н); 7.58 (1Н, d, J67 = 10, 6-Н); 8.05 (1Н, s, 5-Н)
2.30, 2.44 and 2.53 (2×3Н, 3 s, 8-, 9-Ме and МеC6H4); 3.28 (3Н, s, ОМе);
3.65 (2Н, t, β-Н); 3.87 (2Н, t, γ-Н); 4.65 (2Н, s, 4-Н); 6.71 (2Н, d, J = 10, 3'-, 5'-H),
7.12 (2Н, d, J = 10, 2'-, 6'-H); 7.40 (1Н, d, J76 = 10, 7-Н); 7.68 (1Н, d, J67 = 10, 6-Н);
8.18 (1Н, s, 5-Н)
4a
4b
4c
For isothiocyanates which do not contain halogen, the Beilstein test for halogens is a simple and reliable
for monitoring the purity of products 4. It is positive for the amine starting material but negative for the
cyclization products.
EXPERIMENTAL
1H NMR spectra were recorded with a Bruker AM-400 (400 MHz) instrument. Purity of the products
was controlled by TLC on Sorbfil strips with 20:1 chloroform–methanol as eluent.
Synthesis of starting 2-chloro-7,8-dimethyl-3-quinolinecarboxaldehyde (1) was carried out by a
method analogous to that reported in [3].
N-[(2-Chloro-7,8-dimethylquinolin-3-yl)methyl]-2-methoxyethylamine (2). Triethyl orthoformate
(1.6 ml, 15.0 mmol) and 2-methoxyethylamine (0.75 ml, 14.0 mmol) were added to a suspension of aldehyde 1
(3 g, 13.6 mmol) in ethanol (30 ml) – the aldehyde dissolved. The reaction mixture was stirred for 2 h at 50°C.
The precipitate which deposited on cooling was filtered off and washed with ethanol (2 × 10 ml). The Schiff's
base obtained in this way was reduced without further purification by sodium borohydride (0.76 g, 20 mmol) in
methanol (50 ml). The solvent was removed in vacuum and the residue was treated with water (50 ml). The
crystals which separated were filtered off, washed with water (2 × 15 ml), and air dried to give amine 2 (3.67 g)
which was used in further synthesis without further purification. An analytical sample was obtained by
recrystallization from 90% aqueous ethanol.
b
2-Imino-3-(2-methoxyethyl)-8,9-dimethyl-3,4-dihydro-2H-[1,3]thiazino[6,5- ]quinolines
(4a-c).
The corresponding isothiocyanate (1 mmol) was added to a solution of amine 2 (0.278 g, 1 mmol) in ethanol
(3-4 ml). The reaction mixture was boiled for 30 min (controlled by TLC). Potassium hydroxide (0.062 g,
1.1 mmol) was then added and the mixture was boiled for a further 20 min (TLC monitoring). The crystals
which separated after cooling were filtered off, washed with water (2 × 5 ml), and recrystallized from ethanol.
REFERENCES
1.
2.
R. V. Kombarov and M. A. Yurovskaya, Khim. Geterotsikl. Soedin., 1310 (2002).
E. G. Paronikyan, S. N. Sirakanyan, I. S. Narovyan, E. M. Arzanunts, R. G. Paronikyan, I. S. Sarkisyan,
and N. E. Akopyan, Khim.-farm. Zh., 28, 20 (1994).
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