736 JOURNAL OF CHEMICAL RESEARCH 2015
Experimental
+ Na+). Anal. calcd for C21H19NO2: C, 79.47; H, 6.03; N, 4.41; found: C,
79.38; H, 5.98; N, 4.38%.
The recorded melting points are uncorrected. IR spectra were recorded
in KBr on a Shimadzu FTIR spectrophotometer, IR Affinity-1, 1H and
13C NMR spectra were obtained on Bruker 300 or 400 instruments (1H
at 300 MHz or 400 MHz and 13C at 75 MHz, or 100 MHz respectively)
for solutions in CDCl3. Mass spectra were obtained on a Qtof micro
YA 263 instrument and elemental analysis on a PerkinElmer 240c
elemental analyser. Light petroleum refers to the fraction with b.p.
60–80 oC. 2-Aminochromone-3-carbaldehydes 1 were prepared
following a literature procedure.27 All other chemicals used were of
commercial grade and were used as such.
2-[N-(o-Bromobenzyl)-N-p-tolyl)amino]-3,6-dimethylchromone
o
(2e): White crystalline solid; m.p. 120–122 C; IR nmax/cm-1: 3114,
2920, 1614, 1566, 1512, 1388; 1H NMR (CDCl3, 400 MHz): δ 7.96 (1H,
br s, H-5), 7.57 (1H, br d, J = 8.4 Hz, H-7), 7.43 (1H, br d, J = 7.6 Hz,
H-3′′), 7.37 (1H, dd, J = 7.6, 2.0 Hz, H-6′′), 7.26–7.22 (1H, m, H-4′′),
7.20 (1H, d, J = 8.4 Hz, H-8), 7.13–7.10 (1H, m, H-5′′), 7.08 (2H, d, J =
8.0 Hz, H-3′ and H-5′), 6.89 (2H, d, J = 8.0 Hz, H-2′ and H-6′), 5.16 (2H,
s, CH2), 2.43 (3H, s, 6-CH3), 2.30 (3H, s, 4′-CH3), 1.71 (3H, s, 3-CH3);
13C NMR (CDCl3, 100 MHz): δ 179.3, 158.3, 152.4, 142.4, 136.9, 134.5,
133.8, 133.1, 132.9, 130.0, 128.8, 128.3, 127.7, 125.1, 122.4, 122.1,
120.4, 116.8, 107.1, 55.3, 20.9, 20.7, 10.8; MS: (+ve ion electrospray):
m/z 448 (M + H+), 450 (M + 2 + H+), 470 (M + Na+), 472 (M + 2 +
Na+). Anal. calcd for C25H22BrNO2: C, 66.97; H, 4.95; N, 3.12; found:
C, 66.93; H, 4.92; N, 3.09%.
Reduction of 2-[(N-substituted or N-unsubstituted)amino]chromone-
3-carbaldehydes (1) with Zn in acetic acid; general procedure
The 2-aminochromone-3-carbaldehyde derivative 1 (0.25 mmol) was
heated under reflux in acetic acid (5 mL) in the presence of an excess
of Zn powder (1.25 mmol) for 4 h. The reaction mixture was filtered
and the residue was washed with methanol. All the washings and
filtrate were taken together and solvent was removed under reduced
pressure. Ice-water (10 g) was added to the concentrate to produce a
semi solid mass for 2a–e, whereas for reactions with 1f–k, a solid mass
was obtained. The semi-solid or solid mass was dissolved in CHCl3
(10 mL), the CHCl3 solution was washed with water (2 × 10 mL), dried
over Na2SO4 and purified by flash chromatography over silica gel (100-
200 mesh) using 50% light petroleum in toluene for 2a–g and 10%
ethyl acetate in toluene for 7. Compound 7 was further crystallised
from methanol.
3-Methyl-2-(N-phenylamino)chromone (2f): White crystalline
o
solid; m.p. 194–196 C; IR nmax/cm-1: 3235, 3080, 1631, 1599, 1541,
1417; 1H NMR (CDCl3, 300 MHz): δ 8.20 (1H, dd, J = 7.8, 1.2 Hz, H-5),
7.56–7.51 (1H, m, H-7), 7.43–7.32 (5H, m, ArH), 7.29 (1H, br d, J = 8.4
Hz, H-8), 7.21–7.16 (1H, m, H-6), 6.69 (1H, br s, exchangeable, NH),
2.10 (3H, s, 3-CH3); 13C NMR (CDCl3, 75 MHz): δ 176.1, 157.3, 152.9,
137.4, 132.0, 129.4, 125.8, 124.8, 124.6, 122.7, 121.5, 116.6, 96.3, 8.1;
MS: (+ve ion electrospray): m/z 252 (M + H+), 274 (M + Na+). Anal.
calcd for C16H13NO2: C, 76.48; H, 5.21; N, 5.57; found: C, 76.40; H,
5.16; N, 5.53%.
2-(N-p-Chlorophenylamino)-3-methylchromone
(2g):
White
crystalline solid; m.p. >250 oC; IR: nmax/cm-1 3242, 3077, 1640,
3,6-Dimethyl-2-[(N-methyl-N-phenyl)amino]chromone (2a): White
crystalline solid; m.p. 90–92 oC; IR nmax/cm-1: 2984, 2916, 1608, 1560,
1
1602, 1545, 1420; H NMR (DMSO-d6, 300 MHz): δ 9.21 (1H, br s,
1
1390; H NMR (CDCl3, 400 MHz): δ 7.99 (1H, d, J = 1.2 Hz, H-5),
exchangeable, NH), 7.98 (1H, dd, J = 7.8, 1.2 Hz, H-5), 7.66–7.61 (1H,
m, ArH), 7.45–7.37 (6H, m, ArH), 1.99 (3H, s, 3-CH3); MS: (+ve ion
electrospray): m/z 286 (M + H+), 288 (M + 2 + H+), 308 (M + Na+), 310
(M + 2 + Na+). Anal. calcd for C16H12ClNO2: C, 67.26; H, 4.23; N, 4.90;
found: C, 67.19; H, 4.18; N, 4.86%.
7.42 (1H, dd, J = 8.4, 1.2 Hz, H-7), 7.33–7.30 (2H, m, ArH), 7.28 (1H,
d, J = 8.4 Hz, H-8), 7.04–7.01 (1H, m, ArH), 6.97–6.95 (2H, m, ArH),
3.48 (3H, s, CH3-N), 2.46 (3H, s, 6-CH3), 1.71 (3H, s, 3-CH3); MS:
(+ve ion electrospray): m/z 280 (M + H+), 302 (M + Na+). Anal. calcd
for C18H17NO2: C, 77.40; H, 6.13; N, 5.01; found: C, 77.32; H, 6.09; N,
4.97%.
3,6-Dimethyl-4-hydroxycoumarin (7): White crystalline solid; m.p.
o
o
o
255–256 C (lit.30 252–254 C; lit.31 262–263 C); IR nmax/cm-1: 3324,
2-[(N-Allyl-N-p-tolyl)amino]-3,6-dimethylchromone (2b): White
1
3149, 2912, 2870, 1662, 1618, 1581, 1504; H NMR (DMSO-d6, 300
crystalline solid; m.p. 108–110 C; IR nmax/cm-1: 2988, 2916, 1608,
o
MHz): δ 11.17 (1H, br s, exchangeable, OH), 7.69 (1H, d, J = 1.2 Hz,
H-5), 7.39 (1H, dd, J = 8.4, 1.2 Hz, H-7), 7.24 (1H, d, J = 8.4 Hz, H-8),
2.37 (3H, s, CH3-6), 1.99 (3H, s, CH3-3); 13C NMR (CDCl3, 100 MHz):
δ 163.3, 159.9, 149.8, 133.0, 132.2, 122.6, 116.0, 115.8, 100.1, 20.5, 9.8;
MS: (+ve ion electrospray): m/z 191 (M + H+), 213 (M + Na+).
1
1553, 1396; H NMR (CDCl3, 400 MHz): δ 7.98 (1H, d, J = 1.6 Hz,
H-5), 7.40 (1H, dd, J = 8.4, 1.6 Hz, H-7), 7.24 (1H, d, J = 8.4 Hz, H-8),
7.09 (2H, d, J = 8.4 Hz, H-3′ and H-5′), 6.90 (2H, d, J = 8.4 Hz, H-2′
and H-6′), 6.04–5.97 (1H, m, H-vinylic), 5.30–5.26 (1H, m, H-vinylic),
5.18 (1H, dd, J = 10.4, 1.6 Hz, H-vinylic), 4.49–4.48 (2H, m, CH2), 2.45
(3H, s, 6-CH3), 2.31 (3H, s, 4′-CH3), 1.63 (3H, s, 3-CH3); 13C NMR
(CDCl3, 100 MHz): δ 179.2, 158.7, 152.4, 142.2, 134.4, 134.1, 133.6,
133.1, 129.9, 125.2, 122.2, 121.1, 117.4, 116.6, 106.1, 53.9, 20.9, 20.8,
10.7; MS: (+ve ion electrospray): m/z 320 (M + H+), 342 (M + Na+).
Anal. calcd for C21H21NO2: C, 78.97; H, 6.63; N, 4.39; found: C, 78.91;
H, 6.59; N, 4.41%.
We gratefully acknowledge CSIR, New Delhi [Project no.
02(0029)/11/EMR-II] for financial assistance; DST-FIST for
instrumental help at RKMVC College; University of Kalyani
and IICB, Jadavpur for spectral analysis and finally the college
authority for providing other research facilities. J. G. thanks
CSIR for Senior Research Fellowship.
3-Methyl-2-[(N-propargyl-N-p-tolyl)amino]chromone (2c): White
crystalline solid; m.p. 108–110 C; IR nmax/cm-1: 2965, 2918, 1610,
1562, 1514, 1398; H NMR (CDCl3, 400 MHz): δ 8.21 (1H, dd, J =
o
1
Received 16 August 2015; accepted 15 November 2015
Published online: 1 December 2015
8.1, 1.5 Hz, H-5), 7.65–7.59 (1H, m, H-7), 7.43–7.35 (2H, m, H-6 and
H-8), 7.14 (2H, d, J = 8.4 Hz, H-3′ and H-5′), 7.00 (2H, d, J = 8.4 Hz,
H-2′ and H-6′), 4.57 (2H, d, J = 2.4 Hz, CH2), 2.33 (3H, s, 4′-CH3), 2.29
(1H, t, J = 2.4 Hz, H-alkyne), 1.65 (3H, s, 3-CH3); 13C NMR (CDCl3,
100 MHz): δ 179.3, 158.2, 154.3, 141.4, 133.7, 132.7, 130.1, 125.9,
124.7, 122.5, 121.1, 117.1, 107.5, 79.3, 72.8, 40.9, 20.8, 10.4; MS: (+ve
ion electrospray): m/z 304 (M + H+), 326 (M + Na+). Anal. calcd for
C20H17NO2: C, 79.19; H, 5.65; N, 4.62; found: C, 79.09; H, 5.58; N,
4.57%.
References
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2-[N-(2-Butynyl)-N-phenyl)amino]-3,6-dimethylchromone (2d):
White crystalline solid; m.p. 82–84 oC; IR nmax/cm-1: 2987, 2914, 1610,
1
1566, 1394; H NMR (CDCl3, 400 MHz): δ 8.00 (1H, d, J = 2.0 Hz,
H-5), 7.43 (1H, dd, J = 8.4, 2.0 Hz, H-7), 7.33–7.29 (3H, m, ArH),
7.06–7.04 (2H, m, ArH), 7.03 (1H, d, J = 8.4 Hz, H-8), 4.52 (2H, q, J
= 2.0 Hz, CH2), 2.46 (3H, s, 6-CH3), 1.78 (3H, t, J = 2.0 Hz, CH3), 1.71
(3H, s, 3-CH3); MS: (+ve ion electrospray): m/z 318 (M + H+), 340 (M
6
7