KEIKO et al.
1424
hydrazone III, 0.29 g (0.0041 mol) of methyl vinyl
ketone, 0.002 g of hydroquinone, and 1 ml of anhy-
drous benzene. The ampule was sealed, placed into
a metal container, and heated for 5 h at 100–115°C.
According to the H NMR data, the yield of ketone
VII was 80%.
data) compounds IX and VIII at a ratio of 4:1. When
the reaction mixture was heated for 3 h, other condi-
tions being equal, the conversion of initial hydrazone
III was only 34%, and the solid still residue contained
80% of methyl 5-ethoxypyridine-2-carboxylate (VIII).
1H NMR spectrum (CDCl3), δ, ppm: 1.46 t (3H,
CH2CH3, J = 7.0 Hz), 3.97 s (3H, OCH33), 4.13 q (2H,
1
b. An ampule was charged with a mixture of 1 g
(0.07 mol) of hydrazone III, 0.49 g (0.07 mol) of
methyl vinyl ketone, 1 ml of anhydrous benzene, and
0.002 g of hydroquinone. The ampule was sealed,
placed in a Teflon container with a screw cap, and
subjected to microwave irradiation (12×3 min) with
intermediate cooling after each pulse. The mixture was
distilled under reduced pressure. Yield 1.08 g (72.48%),
4
OCH2, J = 7.0 Hz), 7.22 d.d (1H, 4-H, J = 8.7, J =
2
2.8 Hz), 8.09 d (1H, 3-H, J = 8.7 Hz), 8.36 d (1H,
4
6-H, J = 2.8 Hz). Mass spectrum, m/z (Irel, %): 181
(7.8) [M]+, 151 (10.5) [M – OCH2]+, 123 (100) [M –
COOCH2]+, 108 (1.4), 95 (57.9) [M – hydroxy-
pyridine]+, 76 (8.1), 59 (15.4) [COOCH3]+, 50 (10.2),
39 (39.0).
1
bp 95°C (1.5 mm), nD20 = 1.4885. H NMR spectrum
Methyl 5-dimethylaminopyridine-2-carboxylate
(IX). IR spectrum, ν, cm–1: 1720 (C=O), 1590 (C=N).
1H NMR spectrum (CDCl3), δ, ppm: 3.07 s (6H,
NMe2), 3.93 s (3H, OCH3), 6.92 d.d (1H, 4-H, 3J = 8.8,
(CDCl3), δ, ppm: 1.15 t (3H, CH2CH3), J = 7.1 Hz),
1.71 m (1H, 3-H), 1.77 s (3H, COCH3), 1.85 m (1H,
3-H), 1.98 d.d.d (1H, 4-H, J = 1.1, 2.6, 16.2 Hz),
2.17 d.d.d (1H, 4-H, J = 1.1, 2.6, 16.2 Hz), 2.16 m
(1H, 3-H), 2.82 s (6H, NMe2), 3.59 q (2H, OCH2, 3J =
7.0 Hz), 4.57 m (1H, 2-H), 6.49 s (1H, 6-H); the
signals were assigned on the basis of the two-dimen-
sional CH-CORR spectrum. 13C NMR spectrum
(CDCl3), δC, ppm: 15.65 (CH2CH3), 17.73 (C3), 19.95
(CH3CO), 29.73 (C4), 42.74 (NMe2), 57.76 (OCH2),
97.07 (C2), 98.51 (C5), 134.06 (C6), 147.04 (C=O).
Mass spectrum, m/z (Irel, %): 212 (1) [M]+, 166 (100)
[M – EtOH]+, 165 (49.32), 151 (11.3) [M – EtOH2 –
CH3]+, 123 (38.2), 122 (52.2) [M – EtOH – NMe2]+,
108 (21.8), 95 (54.7), 94 (36.2), 80 (17.5), 66 (20.5),
55 (13.0), 43 (64.3) [COCH3]+. Found, %: C 61.50;
H 9.72; N 13.87. C11H20N2O2. Calculated, %: C 62.24;
H 9.50; N 13.20.
2
4J = 3.6 Hz), 7.96 d (1H, 3-H, J = 8.8 Hz), 8.15 d
4
(1H, 6-H, J = 3.6 Hz) (cf. [4]). Mass spectrum, m/z
(Irel, %): 180 (55.5) [M]+, 149 (13.6) [M – OCH3]+, 122
(100) [M – COOCH2]+, 106 (21.6), 94 (13.8), 79
(32.5), 59 (38.1) [COOCH3]+, 42 (80.1).
Reaction of 2-ethoxyprop-2-enal dimethylhydra-
zone (III) with benzoquinone. A flask was filled with
argon and charged with 30 ml of chloroform, 0.27 g
(0.0025 mol) of benzoquinone, and 0.002 g of hydro-
quinone, and 0.36 g (0.0025 mol) of 2-ethoxyprop-2-
enal dimethylhydrazone (III) was added dropwise.
After 15 min, the mixture contained (1H NMR, CDCl3)
the primary [4+2]-cycloaddition product, 1-dimethyl-
amino-3-ethoxy-1,4,4a,5,8,8a-hexahydroquinoline-5,8-
1
dione (X). H NMR spectrum (CDCl3), δ, ppm: 1.25 t
3
3
Reaction of hydrazone III with methyl acrylate.
An ampule was charged with a mixture of 1.2 ml of
benzene, 0.6 g (0.007 mol) of methyl acrylate, 1 g
(0.007 mol) of hydrazone III, and 0.002 g of hydro-
quinone. The ampule was placed into a metal container
and heated for 6 h 35 min at 100°C. According to the
1H NMR data, the yield of methyl 1-dimethylamino-5-
ethoxy-1,2,3,4-tetrahydropyridine-2-carboxylate (VI)
was 76%. By vaccum distillation we isolated 0.9 g
(3H, CH3, J = 7.0 Hz), 2.26 d.d (1H, CH2, J = 1.5,
2J = 17.0 Hz), 2.30 s (6H, CH3N), 2.71 d.d (1H, CH2,
3J = 3.0, J = 17.0 Hz), 3.22 m (1H, 4a-H), 3.60 d.q
(1H, OCH2, J = 7.0 Hz), 3.70 d.q (1H, OCH2, J =
7.0 Hz), 3.81 d (1H, 8a-H, J = 2.4 Hz), 5.33 s (1H,
2
3
3
2-H), 6.63 d (2H, 6-H, 7-H, J = 2.0 Hz). Adduct X was
completely converted in 4 h into 1-dimethylamino-3-
ethoxy-1,4,5,8-tetrahydroquinoline-5,8-dione (XI).
1H NMR spectrum (CDCl3), δ, ppm: 1.16 t (3H,
CH2CH3), 2.81 s (6H, NMe2), 3.13 d (1H, 4-H, J =
16.7 Hz), 3.62 q (2H, OCH2, J = 7.0 Hz), 3.77 d (1H,
4-H, J = 16.7 Hz), 6.56 d and 6.63 d (2H, 6-H, 7-H,
3J = 8.5 Hz), 6.65 s (1H, 2-H). The black tarry material
was removed from the flask to leave dark violet
crystalline drusen of 5-hydroxy-1-benzofuran-2-carb-
aldehyde dimethylhydrazone (XIII). Yield 0.6 g
(95%), mp 172–174°C. IR spectrum, ν, cm–1: 3120,
1610, 1600, 1520, 1508, 1460, 1350, 1330, 1270,
1
(56.07%) of VI with bp 115–119°C (1 mm). H NMR
3
spectrum (CDCl3), δ, ppm: 1.27 t (3H, CH3, J =
7.0 Hz), 2.02 m (2H, CH2), 2.25 m (2H, CH2), 3.52 m
(1H, NCH), 3.64 m (2H, OCH2), 5.51 s (1H, CH=).
Found, %: C 57.36; H 8.78; N 12.59. C11H20N2O3. Cal-
culated, %: C 57.87; H 8.83; N 12.27.
After storage of VI for 2.5 months at 8°C, distilla-
tion gave only 13% of the unchanged compound. The
solid still residue contained (according to the 1H NMR
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 42 No. 10 2006