1498
R. B. SMITH, H. FAKI, AND R. LESLIE
spectrometer. All chemicals and solvents were bought from either Sigma Aldrich or
Alfa Aesar and used without further purification.
N-(3-Methyl-2-pyridyl)aminomethylenemalonates (Table 1,
Reaction A)
A mixture of 2-amino-3-picoline (1.08 g, 10 mmol) and diethyl (ethoxymethyle-
ne)malonate (2 ml, 10 mmol) was irradiated for 30 s in a CEM microwave at half
power. Ethanol (10 ml), was added to the reaction mixture and heated until a clear
solution was obtained, which was treated with activated charcoal, filtered, and
allowed to cool naturally. The solid was filtered under suction and dried under
vacuum to yield N-(3-methyl-2-pyridyl)aminomethylenemalonate (81%) as white
crystals.
1
H NMR (d-CDCl ) d ppm: 1.29–1.39 (t x2, 6H, CH ), 2.31 (s, 3H, Ar-CH ),
3
3
3
4
.19–4.35 (q x2, 4H, CH ), 6.93 (t, 1H, J ¼ 6.1 Hz, Ar-H), 7.46 (d, 1H, J ¼ 6.5 Hz,
2
Ar-H), 8.18 (d, 1H, J ¼ 6.2 Hz, Ar-H), 9.26 (d, 1H, J ¼ 12.5 Hz, C=C-H), 11.32
1
3
(
6
br d, 1H, J ¼ 12.3 Hz, N-H). C NMR (d-CDCl ) d ppm: 14.35, 14.48, 16.41,
3
0.12, 60.60, 95.66, 119.49, 120.21, 139.27, 146.07, 149.12, 149.98, 165.38, 169.32;
MS (LCMS) m=z ¼ 278.
Each of the reactions are based on the same quantities and procedures as the
cyclization of N-(3-methyl-2-pyridyl)aminomethylene malonate.
Ethyl-9-methyl-4-oxo-4H-Pyrido[1,2a]pyrimidine-3-carboxylate
(
Table 2, Reaction A)
mixture of N-(3-methyl-2-pyridyl)aminomethylene malonate (0.70 g,
.5 mmol) and diphenyl ether (10 ml) was irradiated for 15 min in a CEM microwave
at full power. The mixture was allowed to cool to room temperature, and hexane
50 ml) was added with stirring. The yellow solid produced was filtered under suction
A
2
(
and washed with additional hexane (50 ml). The solid was dried under vacuum to
yield ethyl-9-methyl-4-oxo-4H-pyrido[1,2a]pyrimidine-3-carboxylate (0.45 g, 77%)
as a white solid.
1
H NMR (d -DMSO) d ppm: 1.29 (t, 3H, J ¼ 7.1 Hz, CH ), 2.53 (s, 3H, Ar-
6
3
CH ), 4.24 (q, 2H, J ¼ 7.2 Hz, CH ), 7.44 (t, 1H, J ¼ 7.1 Hz, Ar-H), 8.05 (d, 1H,
3
2
1
3
J ¼ 6.9 Hz, Ar-H), 8.83 (s, 1H, Ar-H), 9.01 (d, 1H, J ¼ 7.3 Hz, Ar-H). C (d -
6
DMSO) d ppm: 14.21, 17.43, 60.08, 103.68, 117.53, 126.53, 134.68, 139.30, 152.16,
1
54.06, 157.19, 164.16.
REFERENCES
1
2
. Ball, P. Quinolone generations: Natural history or natural selection? J. Antimicrob.
Chemother. 2000, 46, 17–24.
. Efthimiadou, E. K.; Karaliota, A.; Psomas, G. Mononuclear metal complexes of the
second-generation quinolone antibacterial agent enrofloxacin: Synthesis, structure, antibac-
terial activity, and interaction with DNA. Polyhedron. 2008, 27, 1729–1738.
. Couturier, M.; Bahassi, E. I. M.; Van Melderen, L. Bacterial death by DNA gyrase poison-
ing. Trends Microbiol. 1998, 6, 269–275.
3