K. Chand, R. K. Tiwari, S. Kumar, A. N. Shirazi, S. Sharma, E. V. Van der Eycken,
V. S. Parmar, K. Parang, and S. K. Sharma
Vol 000
7.34–7.39 (m, 2H, H-3, H-5’), 7.50 (d, 1H, J = 8.9 Hz, H-8’), and
8.71 (s, 1H, H-2’); 13C NMR (75.5 MHz, DMSO-d6): δ 108.87,
117.87, 120.67, 121.72, 124.27, 125.25, 137.07, 149.70,
156.18, 160.21, 168.76, and 176.02; HRMS, m/z: calculated for
C12H8O5 [M + Na]+ 255.0269, found 255.0325.
(MeOH) λmax: 272, 246, and 216 nm; IR (KBr) υmax: 3152.11
(OH), 2955.91, 1707.66 (COO), 1648.31 (CO), 1623.63 (C═C),
1571.93, 1412.46, 1287.20, 1243.87, 1169.71, and 849.49cmÀ1
;
1H NMR (400 MHz, CDCl3): δ 0.67 (t, 3H, J = 7.3Hz, H-4"),
1.13–1.18 (m, 2H, H-3"), 1.37–1.44 (m, 2H, H-2"), 3.89 (t, 2H,
J = 6.6 Hz, H-1"), 6.58 (d, 1H, J =2.2 Hz, H-8’), 6.68 (dd, 1H,
J = 2.2 and 8.8 Hz, H-6’), 6.97 (d, 1H, J = 16.1Hz, H-2), 7.12
(d, 1H, J = 16.1Hz, H-3), 7.77 (d, 1H, J = 8.8 Hz, H-5’), 7.88
(s, 1H, H-2’), and 9.51 (brs, 1H, OH); 13C NMR (100.5 MHz,
CDCl3): δ 13.13, 18.49, 30.04, 63.55, 102.08, 115.19, 116.24,
117.99, 120.61, 126.84, 135.40, 156.71, 156.76, 162.54, 166.76,
and 174.73; HRMS, m/z: calculated for C16H16O5 [M + H]+
289.1076, found 289.1081.
General procedure for the synthesis of (E)-3-(4-oxo-4H-1-
benzopyran-3-yl)acrylates 31-46. A mixture of (E)-3-(4-oxo-
4H-1-benzopyran-3-yl)acrylic acid (28-30, 1 g), appropriate
alcohol (50 mL), and conc. sulfuric acid (2–3 drops) was
refluxed. The esterification reaction was monitored by TLC. On
completion of reaction, the reaction mixture was allowed to cool
to room temperature. Then alcohol was evaporated under
reduced pressure, and the resulting product was poured in ice-
cold water with continuous stirring. The precipitated solid was
filtered, washed with water, and purified by column
chromatography using 20–40 % ethyl acetate/petroleum ether as
eluents to give the desired acrylates 31-46 in 90–96% yield
(Scheme 3).
(E)
Methyl
3-(6-hydroxy-4-oxo-4H-1-benzopyran-3-yl)
acrylate (41). Compound 41 was obtained as yellow crystals in
92% yield. mp: 246–247°C; UV (MeOH) λmax: 278, 269, 245,
and 218 nm; IR (KBr) υmax: 3386 (OH), 1699 (COO), 1643 (CO),
1619 (C═C), 1473, 1344, 1316, 1298, 1229, 981, and 864cmÀ1
;
(E) Methyl 3-(4-oxo-4H-1-benzopyran-3-yl)acrylate (31).
Compound 31 was obtained as yellow crystals in 95% yield. mp:
95–96°C (lit. value: 92°C) [32]; UV (MeOH) λmax: 290, 266, and
218 nm; IR (KBr) υmax: 3085, 2953, 1723 (COO), 1647 (CO),
1H NMR (500MHz, DMSO-d6): δ 3.72 (s, 3H, H-1"), 7.20
(d, 1H, J = 16.0 Hz, H-2), 7.26 (dd, 1H, J = 3.0 and 9.0Hz, H-7’),
7.39 (d, 1H, J = 3.0 Hz, H-5’), 7.48 (d, 1H, J = 16.0Hz, H-3), 7.58
(d, 1H, J = 9.0Hz, H-8’), 8.84 (s, 1H, H-2’), and 10.15 (s, 1H,
OH); 13C NMR (125.5 MHz, DMSO-d6): δ 51.43, 107.95, 116.81,
119.33, 119.90, 123.41, 124.40, 136.90, 148.81, 155.34, 160.00,
166.98, and 175.09; HRMS, m/z: calculated for C13H10O5
[M+ Na]+ 269.0426, found 269.0433.
1614 (C═C), 1560, 1467, 1365, 1266, 1041, 990, and 863 cmÀ1
;
1H NMR (500MHz, CDCl3): δ 3.81 (s, 3H, H-1"), 7.29 (d, 1H,
J = 15.8 Hz, H-2), 7.40–7.51 (m, 3H, H-3, H-6’, and H-8’), 7.72
(t, 1H, J =7.6 Hz, H-7’), 8.13 (s, 1H, H-2’), and 8.30 (d, 1H,
J = 7.8Hz, H-5’); 13C NMR (125.5MHz, CDCl3): δ 52.06,
118.50, 119.77, 122.24, 124.66, 126.24, 126.78, 134.39, 135.99,
155.97, 157.72, 169.11, and 178.78; HRMS, m/z: calculated for
C13H10O4 [M + Na]+ 253.0477, found 253.0464.
(E) Ethyl 3-(6-hydroxy-4-oxo-4H-1-benzopyran-3-yl)acrylate
(42).
Compound 42 was obtained as yellow crystals in 96%
yield. mp: 179–180°C; UV (MeOH) λmax: 278, 246, and 216nm;
IR (KBr) υmax: 3342 (OH), 3050, 2985, 1687 (COO), 1655 (CO),
(E) Butyl 3-(4-oxo-4H-1-benzopyran-3-yl)acrylate (35) [33].
Compound 35 was obtained as yellow crystals in 98% yield. mp:
129–130°C; UV (MeOH) λmax: 289, 265, and 217 nm; IR (KBr)
1604 (C═C), 1470, 1342, 1294, 1227, 985, and 867cmÀ1
;
1H NMR (300MHz, DMSO-d6): δ 1.25 (t, J = 7.0 Hz, 3H, H-2"),
4.17 (q, J = 7.0 Hz, 2H, H-1"), 7.16 (d, 1H, J = 16.0Hz, H-2),
7.22–7.26 (dd, 1H, J = 3.0 and 9.0Hz, H-7’), 7.38 (d, 1H,
J = 3.0 Hz, H-5’), 7.45 (d, 1H, J = 16.0Hz, H-3), 7.55 (d, 1H,
J = 9.0 Hz, H-8’), 8.81 (s, 1H, H-2’), and 10.10 (s, 1H, -OH);
13C NMR (75.5MHz, DMSO-d6): δ 17.03, 62.78, 110.86, 119.75,
122.63, 122.72, 126.25, 127.28, 139.44, 151.69, 158.21, 162.63,
169.34, and 177.93; HRMS, m/z: calculated for C14H12O5
[M+ Na]+ 283.0582, found 283.0591.
υ
max: 3063, 2958, 2932, 2871, 1706 (COO), 1657 (CO), 1613
(C═C), 1561, 1469, 1356, 1292, 1265, 1162, 1033, 997, and
857 cmÀ1 1H NMR (500 MHz, CDCl3,): δ 0.96 (t, J = 6.4 Hz,
;
3H, H-4"), 1.39–1.47 (m, 2H, H-3"), 1.65–1.71 (m, 2H, H-2"),
4.20 (t, J = 6.8 Hz, 2H, H-1"), 7.28 (d, 1H, J = 15.8 Hz, H-2),
7.38–7.48 (m, 3H, H-3, H-6’ and H-8’), 7.68 (t, 1H, J = 7.6 Hz,
H-7’), 8.11 (s, 1H, H-2’), and 8.26 (d, 1H, J = 7.9 Hz, H-5’);
13C NMR (125.5 MHz, CDCl3): δ 14.08, 19.56, 31.15, 64.76,
118.48, 119.77, 122.67, 124.61, 125.52, 126.18, 134.35,
135.62, 155.97, 157.65, 167.79, and 176.23; EIMS, m/z: 272.11
(M+.), 215.04 (M+. À C4H9), 199.04 (M+. À OC4H9), 189.90,
171.04 (M+. À OC4H9-CO), 149.95, 115.06, 82.93, and 57.02
(C4H+9).
(E) Propyl 3-(6-hydroxy-4-oxo-4H-1-benzopyran-3-yl)acrylate
(43). Compound 43 was obtained as yellow crystals in 94% yield.
mp: 177–178°C; UV (MeOH) λmax: 278, 269, 247, and 217nm;
IR (KBr) υmax: 3369 (OH), 3071, 2967, 2880, 1687 (COO), 1654
(CO), 1605 (C═C), 1471, 1316, 1292, 1223, 1186, 984, and
866 cmÀ1. 1H NMR (300MHz, DMSO-d6): δ 0.94 (t, J = 7.4, 3H,
H-3"), 1.63–1.70 (m, 2H, H-2"), 4.09 (t, J = 6.6, 2H, H-1"), 7.13
(d, 1H, J = 15.9Hz, H-2), 7.23–7.27 (m, 1H, H-7’), 7.39 (d, 1H,
J = 3.0 Hz, H-5’), 7.47 (d, 1H, J = 15.9Hz, H-3), 7.55 (d, 1H,
J = 9.0 Hz, H-8’), 8.82 (s, 1H, H-2’), and 10.15 (s, 1H, OH);
13C NMR (75.5 MHz, DMSO-d6): δ 10.65, 21.98, 65.75, 108.37,
117.26, 120.09, 120.17, 123.73, 124.79, 136.97, 149.18, 155.71,
160.15, 166.93, and 175.44; HRMS, m/z: calculated for C15H14O5
[M+ Na]+ 297.0739, found 297.0723.
(E)
Methyl
3-(7-hydroxy-4-oxo-4H-1-benzopyran-3-yl)
acrylate (36). Compound 36 was obtained as yellow crystals in
83% yield. mp: 249–250°C; UV (MeOH) λmax: 263 and 255nm;
IR (KBr) υmax: 3083 (OH), 1718.34 (COO), 1654.39 (CO),
1630.29 (C═C), 1457.49, 1437.10, 1289.47, 1170.35, 1099.79,
841.47, and 783.93 cmÀ1 1H NMR (400MHz, CDCl3): δ 3.22
;
(s, 3H, H-1"), 6.31 (d, 1H, J = 2.2 Hz, H-8’), 6.39 (d, 1H,
J = 8.8Hz, H-6’), 6.68 (d, 1H, J = 16.1 Hz, H-2), 6.88 (d, 1H,
J = 16.1 Hz, H-3), 7.46 (d, 1H, J = 8.8 Hz, H-5’), 7.79 (s, 1H,
H-2’), 9.98 (brs, 1H, OH); 13C NMR (100.5 MHz, CDCl3):
(E) Isopropyl 3-(6-hydroxy-4-oxo-4H-1-benzopyran-3-yl)
acrylate (44). The title compound 44 was obtained as yellow
crystals in 95% yield. mp: 183–184°C; UV (MeOH) λmax: 279,
270, and 217 nm; IR (KBr) υmax: 3371 (OH), 2979, 1702 (COO),
1655 (CO), 1605 (C═C), 1470, 1340, 1291, 1224, 1187, 1106,
δ
50.26, 101.45, 114.57, 115.51, 117.14, 119.22, 126.11,
133.37,156.05, 156.90, 162.01, 166.29, and 173.91; HRMS,
m/z: calculated for C13H10O5 [M+ Na]+ 269.0426, found 269.0437.
(E) Butyl 3-(7-hydroxy-4-oxo-4H-1-benzopyran-3-yl)acrylate
985, and 868 cmÀ1 1H NMR (300 MHz, DMSO-d6): δ 1.24
;
(40).
Compound 40 was obtained as yellow crystals in 83%
(d, 6H, J =6.2 Hz, H-2"), 4.97–5.01 (m, 1H, H-1"), 7.13 (d, 1H,
yield following the general procedure; mp: 149–150°C; UV
J = 16.0Hz, H-2), 7.22–7.26 (dd, 1H, J = 3.0 and 9.0Hz, H-7’),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet