2
66
Short Papers
SYNTHESIS
1
In conclusion, we have shown that it is possible to convert
H NMR (CDCl ): d = 1.50–1.90 (m, 4 H, H-6,7), 2.05–2.55 (m, 4 H,
3
spirocomponds 1 into 5,6,7,8-tetrahydroquinolin-2-ones 2 H-5,8), 7.33 (m, 5 Harom), 7.41 (s, 1 H, H-4), 12.70 (m, 1 H, exch.
D O, NH).
in a one step reaction. In comparison with other synthetic
2
3
approaches, our method offers an efficient way of selec-
Ethyl 1,2,5,6,7,8-Hexahydro-2-oxo-3-phenylquinolin-4-carboxylate
tively reducing the heterocyclic ring of compounds 2 and
to prepare further analogs.
(
2d): mp 240°C.
IR (KBr): n = 3150 (NH), 1725 (C=O ester), 1640 (C=O lactam),
610 cm–1 (C=C).
1
1
H NMR (CDCl ): d = 1.05 (t, J = 8.2 Hz, 3 H, CH ), 1.50–1.90 (m,
1H NMR spectra were recorded at 200 MHz on a Bruker AC200 spec-
3
3
4
H, H-6,7), 2.25–2.70 (m, 4 H, H-5,8), 4.05 (q, J = 8.2 Hz, 2,H,
trometer, using TMS as an internal standard. IR spectra were recorded
on a FTIR-8101 Shimadzu spectrometer. Melting points were taken
on an Electrothermal 9300 capillary melting point apparatus and are
uncorrected. TLC was performed on silica gel plates (Merck F-254)
CH O), 7.33 (m, 5 H ), 12.90 (m, 1 H, exch. D O, NH).
2
arom
2
Methyl 1,2,5,6,7,8-Hexahydro-2-oxo-3-phenylquinolin-4-carboxy-
late (2e): mp 278 °C.
(
CH Cl /EtOAc/AcOH 70:29:1).
2 2
IR (KBr): n = 3150 (NH), 1725 (C=O ester), 1640 (C=O lactam),
1
610 cm–1 (C=C).
1
5
,6,7,8-Tetrahydroquinolin-2(1H)-ones 2; General Procedure:
H NMR (CDCl ): d = 1.55–1.95 (m, 4 H, H-6,7), 2.20–2.75 (m, 4 H,
3
To a solution of the spiro compound 1 (3 mmol) in glacial AcOH
15 mL) was added dropwise concd H SO (1.2 g, 12,2 mmol). The
H-5,8), 3.56 (s, 3H, CH O), 7.35 (m, 5 H
), 12.60 (m, 1 H, exch.
3
arom
(
2
4
D O, NH).
2
mixture was stirred at 60 °C for 30 min. After the completion of the
reaction, the mixture was cooled, then Et O (25 mL) and H O (25
2
2
3-Hydroxy-4-phenylpyrroline-2,5-dione (3):
mL) were successively added. The organic phase was separated and
A solution of the spirocompound 1d (0.5 g, 1.59 mmol) in aq AcOH
(1:1, 30 mL) was refluxed for 45 min. The mixture was evaporated to
dryness under reduced pressure and the residue recrystallized from
washed with 8% aq NaHCO solution. The corresponding tetrahydro-
3
quinolin-2-one 2 precipitated during this process and was isolated by
filtration, washed with H O and dried.
4
2
EtOAc to give 3; mp 212°C (Lit. mp 216°C).
–1
IR (KBr): n = 3220 (OH, NH), 1701 (C=O), 1600 cm (C=C).
1
5
,6,7,8-Tetrahydro-4-methylquinolin-2(1H)-one (2a): mp 241 °C
3d
H NMR (DMSO-d ): d = 7.14-7.30 (m, 5 Harom.), 11,20 (m, 1 H,
6
(Lit. mp 240–241°C).
exch. D O, NH).
2
–1
IR (KBr): n = 3150 (NH), 1640 (C=O), 1610 cm (C=C).
1
H NMR (CDCl ): d = 1.50–1.90 (m, 4 H, H-6,7), 2.12 (s, 3 H, CH ),
3
3
2
.05–2.55 (m, 4 H, H-5,8), 6.41, (s, 1 H, H-3), 11.80 (m, 1 H, exch.
(1) Stambach, J. F.; Jung L.; Hug R. Heterocycles 1994, 38, 297.
D O, NH).
2
(2) Stambach, J. F.; Jung L.; Hug R. Heterocycles 1997, 45, 1825.
(
3) (a) Baldwin, J. E.; Fleming, R. H.; Simmons, D. M. J.Org.Chem.
4
-Ethyl-5, 6,7,8-tetrahydro-3-methylquinolin-2(1H)-one (2b):
1972, 24, 3963.
mp 228°C.
(b) Junek, H.; Wolfeis, O. S.; Sprintschnik, H.; Wolny, H. Mo-
natsch. Chem. 1977, I08, 689.
(c) Sakurai, A.; Midorikawa, H. Bull. Chem. Soc. Jpn. 1968, 41,
165.
–1
IR (KBr): n = 3150 (NH), 1640 (C=O), 1610 cm (C=C).
1
H NMR (CDCl ): d = 1.26 (t, J = 8.1 Hz, 3 H, CH CH ), 1.50–1.90
3
3
2
(m, 4 H, H-6,7), 1.95 (s, 3 H, CH at C-3), 2.05–2.55 (m, 4 H, H-5,8),
3
2
.41 (q, J = 8.1 Hz, 2 H, CH CH ),12.10 (m, 1 H, exch. D O, NH).
(d) Meyers,A. I.; Garcia-Munoz, G. J.Org. Chem. 1964, 29, 1435.
3
2
2
(
e) Thesing, J.; Müller, A. Chem. Ber. 1957, 90, 711.
(f) Sen-Gupta, H. K. J. Chem. Soc. 1915, 107, 1347.
(4) Harlay, V. J. Pharm. Chim. 1936, 24, 537.
5
,6, 7,8-Tetrahydro-3-phenylquinolin-2(1H)-one (2c): mp 241 °C.
–1
IR (KBr): n = 3150 (NH), 1640 (C=O), 1610 cm (C=C).