1
rected. NMR spectra were recorded at 200 MHz for H and
(which dissolves any impurities), and recrystallized from
50 MHz for 13C. All J values are given in Hz. Triazole esters 7
(R = OEt) were prepared from ethyl propiolate and aryl azides,
themselves prepared from the corresponding anilines, accord-
ing to literature procedures.15 Azides are potentially explosive,
and due care should be exercised working with them. 2,2-
Dimethyl-5-(phenylaminomethylene)-1,3-dioxane-4,6-dione 16
and quinolone 15 were prepared as previously described.10,16
CHCl3–MeOH (3:1).
2-(N,N-Dimethylamino)-4-quinolone (12d). Cream solid; yield
69% (at 800 ЊC the same compound was obtained in 54% yield);
mp 294–296 ЊC (decomp.) (Found: C, 69.88; H, 6.42; N, 14.53;
Mϩ 188.0950. C11H12N2O requires C, 70.18; H, 6.43; N, 14.89%;
Mϩ 188.0950); νmax(KBr)/cmϪ1 3438, 1641, 1594, 1541, 1490,
1466, 1435, 1402, 1346, 1301, 1262, 1170, 801, 752; δH(200
MHz; [2H6]DMSO) 3.07 (6H, s, 2 × CH3), 5.44 (1H, br s, 3-H),
7.13 (1H, t, J 7.3), 7.46 (1H, t, J 7.0 and 7.3), 7.55 (1H, d, J 7.9),
7.90 (1H, d, J 7.9), 10.20 (1H, br s, NH); δC([2H6]DMSO) 39.2
[N(CH3)2], 89.9 (CH, C-3), 118.4, 122.7, 123.3, 125.3, 131.4,
General procedure for the preparation of 1-aryl-1H-1,2,3-tri-
azole-4-carboxylic acids 7a–c
A mixture of the corresponding triazole ethyl ester15 (10 mmol)
and 6 HCl (20 cm3) was stirred at 80 ЊC overnight. The mix-
ture was cooled to 10 ЊC and the solid was filtered, washed with
water and dried. GCMS analysis of the crude materials indi-
cated that the acids 7a–c had been formed in good purity; 7a:
off-white solid; crude yield 75%; 7b: white crystals; crude yield
82%; 7c: pale brown light solid; crude yield 68%. The carboxylic
acids were used without further purification in the next step.
139.7, 154.4 (quat., C-2), 168.4 (C᎐O).
᎐
2-(N,N-Dimethylamino)-6-fluoro-4-quinolone (12e). Cream
solid; yield 63%; mp 297–299 ЊC (decomp.) (Found: C, 63.91;
H, 5.42; N, 13.22; Mϩ 206.0855. C11H11N2OF requires C, 64.05;
H, 5.38; N, 13.59%; Mϩ 206.0855) νmax(KBr)/cmϪ1 3440, 1635,
1602, 1544, 1469, 1423, 1399, 1553, 1299, 1255, 1195, 1170, 946,
819, 805, 730; δH(200 MHz; [2H6]DMSO) 3.06 (6H, s, 2 × CH3),
5.70 (1H, br s, 3-H), 7.28 (1H, dt, J 3.5 and 8.7), 7.55 (1H, dd,
J 3.1 and 9.5), 7.61 (1H, dd, J 4.8 and 9.1), 10.26 (1H, br s,
NH); δC([2H6]DMSO) 38.9 [N(CH3)2], 89.9 (CH, C-3), 107.7,
108.8, 118.3, 119.0, 135.5, 154.1 (quat., C-2), 156.3 (quat., C-6),
Representative procedure for the preparation of N,N-dimethyl-1-
aryl-1H-1,2,3-triazole-4-carboxamides 7d–f
Compound 7a (0.9 g, 4.76 mmol) in SOCl2 (10 cm3) was
refluxed for 1 h under N2. Excess SOCl2 was removed by distil-
lation with protection from moisture. Dimethylamine (2 equiv.)
in CH2Cl2 was added dropwise to a cold (10 ЊC) solution of the
crude acid chloride in CH2Cl2 (10 cm3). After the mixture had
been stirred for 30 min, it was washed with water (2 × 25 cm3).
The organic layer was washed with saturated aq. NaCl, dried
(Na2SO4), and concentrated to furnish a white solid (1 g).
The crude product was recrystallized in hot CCl4 (10 cm3) to
give N,N-dimethyl-1-phenyl-1H-1,2,3-triazole-4-carboxamide
7d (0.9 g, 87%), mp 150–151 ЊC (Found: C, 60.74; H, 5.58; N,
26.15; Mϩ 216.1014. C11H12N4O requires C, 61.08; H, 5.60; N,
25.92%; Mϩ 216.1011); νmax(KBr)/cmϪ1 3115, 1623, 1614, 1545,
1394, 1249, 1158, 1046, 865, 766; δH(200 MHz; CDCl3) 3.16
(3H, s, CH3), 3.60 (3H, s, CH3), 7.47–7.60 (3H, m, ArH), 7.75–
7.80 (2H, m, ArH), 8.56 (1H, s, 5-H); δC(50 MHz; CDCl3) 36.2
(CH3), 38.6 (CH3), 120.4, 125.9 (CH, C-5), 129.0, 129.8, 136.3,
173.8 (C᎐O).
᎐
2-(N,N-Dimethylamino)-6-methoxy-4-quinolone (12f). Cream
solid; yield 57%; mp 264–266 ЊC (decomp.) (Found: Mϩ
218.1053. C12H14N2O2 requires Mϩ 218.1055); νmax(KBr)/cmϪ1
3429, 1646, 1602, 1535, 1461, 1401, 1297, 1172, 828; δH(200
MHz; [2H6]DMSO) 3.03 (6H, s, 2 × CH3), 3.76 (3H, s, OCH3)
5.47 (1H, br s, 3-H), 7.00 (1H, dd, J 2.6 and 8.8), 7.30 (1H, d,
J 2.6), 7.65 (1H, d, J 8), 10.49 (1H, br s, N-H); δC([2H6]DMSO)
38.8 [N(CH3)2], 55.2 (OCH3), 89.3 (CH, C-3), 107.2, 119.7,
120.2, 122.5, 133.9, 152.4 (quat., C-2), 154.3 (quat., C-6), 171.5
(C᎐O).
᎐
FVT/matrix isolation
The triazoles 7 (30 mg) were placed in the quartz thermolysis
tube in an oven directly attached to the vacuum system. After
evacuating the oven, the cryostat was turned on and the pres-
sure brought to 2 × 10Ϫ5 mbar while the BaF2 disk reached a
temperature of 12 K. Argon was passed over the sample while it
was sublimed at ca. 80 ЊC through the FVT tube maintained at
different temperatures, and the products were co-deposited on
the disk at 12 K for FTIR spectroscopy. Deposition at 77 K was
performed analogously, except that no carrier gas was used, and
the deposition disk was cooled with liquid N2.
145.0 (quat., C-4), 160.9 (C᎐O).
᎐
N,N-Dimethyl-1-(p-fluorophenyl)-1H-1,2,3-triazole-4-carbox-
amide 7e. Prepared from 0.8 g of 7b to give 0.77 g (85%) after
crystallization from CCl4–EtOH (4:1), mp 183–185 ЊC (Found:
C, 56.35; H, 4.84; N, 23.83; Mϩ 234.0917. C11H11N4OF requires
C, 56.39; H, 4.74; N, 23.93%; Mϩ 234.0917); νmax(KBr)/cmϪ1
3112, 1616, 1542, 1518, 1385, 1258, 1161, 1039, 845, 766; δH(200
MHz; CDCl3) 3.16 (3H, s, CH3), 3.60 (3H, s, CH3), 7.24 (2H,
dd, J 7.9 and 10.1), 7.78 (2H, dd, J 4.6 and 9.1), 8.58 (1H, s,
5-H); δC(CDCl3) 36.2 (CH3), 38.6 (CH3), 116.7 (C-3Ј, d, JCF 23),
122.5 (C-2Ј, d, JCF 8.6), 126.2 (CH, C-5), 132.7 (quat., C-1Ј),
FVT of 16. Carried out as previously described10 with iso-
lation of the products neat at Ϫ196 ЊC or in Ar matrix at 12 K
for IR spectroscopy. Preparative FVT of 16 at 500 and 600 ЊC
gave pure quinolone 15.10,16
High temperature FVT of 7d. The formation of small
amounts (р10%) of 15 on FVT of 7d above 600 ЊC was estab-
lished by TLC and 1H NMR spectroscopy of the acetone-
soluble portion of the thermolysate (recorded in CDCl3
solution) with direct comparison with the authentic material.
The acetone-insoluble fraction under these conditions was pure
quinolone 12d (NMR recorded in [2H6]DMSO).
145.2 (quat., C-4), 160.8 (C᎐O), 162.5 (C-4Ј, d, JCF 248).
᎐
N,N-Dimethyl-1-(p-methoxyphenyl)-1H-1,2,3-triazole-4-
carboxamide 7f. Prepared from 0.95 g of 7c to give 0.7 g (65%),
mp 145–147 ЊC (Found: C, 58.38; H, 5.71; N, 22.54; Mϩ
246.1117. C12H14N4O2 requires C, 58.51; H, 5.73; N, 22.76%;
Mϩ 246.1117); νmax(KBr)/cmϪ1 3132, 1636, 1538, 1525, 1393,
1258, 1178, 1043, 826, 759; δH(200 MHz; CDCl3) 3.16 (3H, s,
CH3), 3.60 (3H, s, CH3), 3.88 (3H, s, OCH3), 7.04 (2H, d, J 9.0),
7.66 (2H, d, J 9.0), 8.43 (1H, s, 5-H); δC(CDCl3) 36.4 (CH3),
38.8 (CH3), 55.6 (OCH3), 114.9, 122.2, 126.0, 129.9, 145.0
Acknowledgements
(quat., C-4), 160.1 (quat., OCH ), 161.2 (C᎐O).
᎐
3
This research was supported by the Australian Research
Council. We thank Dr Jens Morawietz for initial assistance with
matrix isolation experiments.
General procedure for the synthesis of quinolones 12d–f (FVT of
7d–f)
Compounds 7d–f were vaporized at 80–130 ЊC (depending on
volatility) into the preparative thermolysis tube maintained at
600 ЊC in the course of 4 h. The thermolysate was condensed
on the cold finger at 77 K (liq. N2). Upon completion of the
reaction, the system pressure was equalized with N2, and the
product was collected after rinsing the cold finger with acetone
References
1 D. Clarke, R. W. Mares and H. McNab, J. Chem. Soc., Chem.
Commun., 1993, 1020; J. Chem. Soc., Perkin Trans. 1, 1997, 1799.
2 B. E. Fulloon and C. Wentrup, J. Org. Chem., 1996, 61, 1363.
J. Chem. Soc., Perkin Trans. 1, 1998
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