dibenzo[b,h][1,6]naphthyridine derivatives generated from the
coupling of 2-aminoacetophenones and 2-aminobenzophenones
with dihydroquinolin-4-ones. This reaction does not require
expensive catalysts and allows for the efficient isolation of pure
products in good yields. Additionally, it allows the synthesis of
more diverse analogues, closely related to the dependensin
natural product which is known to exhibit anti-malarial activity.1
A small library of novel compounds was synthesized and will be
evaluated for their anti-cancer and anti-malarial biological
activity.
(3 60 mL). The combined organic extracts were washed
with brine, dried over Na2SO4 and the solvent removed
under reduced pressure. The crude product was
recrystallized from methanol to give product 6a as yellow
1
needles (57 %). m.p. 113-115 °C. H NMR (400 MHz,
DMSO-d6) δ 8.38 (dd, J = 7.9, 1.6 Hz, 1H), 8.10 (dd, J =
8.5, 1.2 Hz, 1H), 7.74 (ddd, J = 8.4, 6.8, 1.4 Hz, 1H), 7.63
(m, 1H), 7.54 – 7.35 (m, 3H), 7.31 (t, J = 7.6 Hz, 1H), 7.25
(d, J = 8.5 Hz, 1H), 7.19 – 7.03 (m, 4H), 6.97 (d, J = 2.7
Hz, 1H), 6.83 (dt, J = 5.9, 3.5 Hz, 2H), 6.76 – 6.65 (m,
3H), 5.41 (d, J = 2.6 Hz, 1H).13C NMR (151 MHz,
DMSO) δ 168.6, 151.3, 149.9, 147.1, 144.8, 137.1, 135.0,
131.6, 131.5, 129.9, 129.4, 128.9, 128.8, 128.6, 128.3,
128.1, 127.3, 127.1, 126.6, 126.1, 125.8, 125.1, 123.7,
120.5, 120.0, 117.3, 115.2, 54.9. IR (ATR): νmax 3585,
3263, 2928, 2815, 2210, 1901, 1807, 1717, 1604, 1573,
1489 cm-1. UV-VIS: λmax 389 nm (ε 12447 cm-1M-1).
HRMS (C28H21N2) calcd m/z 385.1699 [M+H]+, obsd m/z
385.1695 [M+H]+.
X-ray crystallography: Suitable single crystal of 6a (CCDC
1500299), obtained from methanol, was selected under the
polarizing microscope (Leica M165Z), mounted on a
MicroMount (MiTeGen, USA) consisting of a thin
polymer tip with a wicking aperture.20 Crystal data:
C28H20N2, M.W. =, Monoclinic,. Cell dimensions: a =
5.1528(15) Å, b = 34.231(12) Å, c = 11.188(3) and beta =
92.651(18) Å. Crystallographic data excluding structure
factors have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication
number CCDC 1500299. A copy of the data can be
obtained free of charge from CCDC, 12 Union Road,
Acknowledgments
We thank the NMR and BMSF facility, University of New South
Wales. We also thank the University of New South Wales and
the Australian Research Council for their financial support.
References and Notes
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Representative procedure for compound 6a: To a mixture
of 2-aminobenzophenone (1.1 mmol, 0.22 g) and 2-phenyl-
2,3-dihydroquinolin-4-one (1.1 mmol, 0.25 g) was added
T3P (2.2 mmol, 0.70 g) and the reaction mixture stirred
18.
°
at 60 C for 24 h. Water (100 mL) was added to dissolve
T3P and the mixture extracted with dichloromethane