M. Choi et al.
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(M ? Na?); H NMR (CDCl3, 400 MHz) d 8.22 (m, 1H),
(CDCl3, 100 MHz) d 169.5, 153.0, 136.1, 133.0, 130.6,
127.9, 127.6, 127.3, 127.0, 126.3, 125.3, 122.8, 121.7,
121.1, 121.0, 119.2, 144.9, 81.3, 34.8.
8.07 (m, 1H), 7.67 (s, 1H), 7.64–7.60 (m, 2H), 7.54 (d, 2H,
J = 8.7 Hz), 7.32 (t, 2H, J = 8.4 Hz), 7.13 (t, 1H,
J = 8.4 Hz), 5.49 (dd, 1H, J = 10.8, 6.6 Hz), 3.86 (dd,
1H, J = 16.2, 10.8 Hz), 3.73 (dd, 1H, J = 16.2, 6.6 Hz);
13C NMR (CDCl3, 100 MHz) d 169.9, 153.2, 136.8, 134.0,
129.1, 128.2, 126.9, 126.1, 124.9, 122.7, 122.1, 120.7,
120.0, 119.7, 118.8, 81.2, 35.0.
5-Chloro-2,3-dihydronaphtho[1,2-b]furan-2-carboxylic acid
N-(3,5-dichlorophenyl)amide (2f) Yield 21.7 %; m.
p. 158.3–163.7 °C; IR 3306, 1684, 1187, 737, 668 cm-1
;
MS(ESI) m/z 416.2 (M ? Na?); 1H NMR (CDCl3,
400 MHz) d 8.23 (m, 1H), 8.04 (m, 1H), 7.67 (s, 1H),
7.64–7.61 (m, 2H), 7.52 (d, 2H, J = 1.8 Hz), 7.12 (t, 1H,
J = 1.8 Hz), 5.47 (dd, 1H, J = 11.0, 6.5 Hz), 3.86 (dd,
1H, J = 16.2, 11.0 Hz), 3.70 (dd, 1H, J = 16.2, 6.5 Hz);
13C NMR (CDCl3, 100 MHz) d 169.6, 152.9, 138.4, 135.4,
131.9, 127.9, 127.6, 127.0, 126.3, 125.0, 121.3, 121.1,
119.4, 118.3, 115.0, 81.2, 34.7.
5-Chloro-2,3-dihydronaphtho[1,2-b]furan-2-carboxylic acid
N-(4-methoxyphenyl)amide (2b) Yield 42.7 %; m.
p. 156.3–157.1 °C; IR 3313, 1656, 1177, 736 cm-1
;
MS(ESI) m/z 379.9 (M ? Na?); 1H NMR (CDCl3,
400 MHz) d 8.20 (m, 1H), 7.84 (m, 1H), 7.62 (s, 1H),
7.59–7.53 (m, 2H), 6.89 (d, 2H, J = 8.6 Hz), 6.61 (d, 2H,
J = 8.6 Hz), 5.31 (dd, 1H, J = 11.1, 5.9 Hz), 3.73 (dd, 1H,
J = 16.0, 11.1 Hz), 3.71 (s, 1H), 3.56 (dd, 1H, J = 16.0,
5.9 Hz); 13C NMR (CDCl3, 100 MHz) d 171.1, 158.3, 153.3,
131.7, 130.2, 129.6, 127.6, 127.4, 126.5, 125.0, 124.3, 121.3,
121.2, 119.7, 114.0, 81.3, 55.2, 34.6.
5-Chloro-2,3-dihydronaphtho[1,2-b]furan-2-carboxylic acid
N-(3,5-ditrifluoromethylphenyl)amide (2g) Yield 31.6 %;
m. p. 156.1–158.4 °C; IR 3309, 1672, 1175, 1129, 760,
721 cm-1; MS(ESI) m/z 482.92 (M ? Na?); 1H NMR
(CDCl3, 400 MHz) d 8.23 (m, 1H), 8.09–8.07 (m, 3H),
7.67 (s, 1H), 7.64–7.62 (m, 2H), 7.03 (s, 1H), 5.51 (dd, 1H,
J = 10.9, 6.6 Hz), 3.88 (dd, 1H, J = 16.2, 10.9 Hz), 3.72
(dd, 1H, J = 16.2, 6.6 Hz); 13C NMR (CDCl3, 100 MHz)
d 167.0, 153.3, 143.4, 138.1, 135.8, 132.7, 132.5, 132.0,
127.9, 127.7, 127.1, 126.3, 121.1, 119.8, 119.4, 115.1,
81.1, 34.7.
5-Chloro-2,3-dihydronaphtho[1,2-b]furan-2-carboxylic acid
N-(3-chlorophenyl)amide (2c) Yield 19.4 %; m. p. 177.5–
179.8 °C; IR 3250, 1670, 1203, 737, 669 cm-1; MS(ESI)
m/z 390.2 (M ? Na?); 1H NMR (CDCl3, 400 MHz) d 8.27
(m, 1H), 8.10 (m, 1H), 7.71–7.70 (m, 2H), 7.67–7.64 (m,
2H), 7.43 (d, 1H, J = 8.2 Hz), 7.29 (t, 1H, J = 9.0 Hz),
7.15 (d, 1H, J = 8.2 Hz), 5.52 (dd, 1H, J = 10.9, 6.5 Hz),
3.90 (dd, 1H, J = 16.0, 10.9 Hz), 3.75 (dd, 1H, J = 16.0,
6.5 Hz); 13C NMR (CDCl3, 100 MHz) d 169.5, 153.0,
137.8, 134.8, 131.9, 130.1, 127.8, 127.6, 127.0, 126.4,
125.1, 121.3, 121.1, 120.1, 119.6, 118.0, 114.8, 81.3, 34.7.
5-Chloro-2,3-dihydronaphtho[1,2-b]furan-2-carboxylic acid
N-(2-trifluoromethylphenyl)amide (2h) Yield 6.3 %; m.
p. 153.2–163.9 °C; IR 3410, 1698, 1163, 1106, 759,
680 cm-1; MS(ESI) m/z 414.2 (M ? H?); 1H NMR
(CDCl3, 400 MHz) d 8.40 (d, 1H, J = 8.3 Hz), 8.22 (m,
1H), 8.06 (m, 1H), 7.67 (s, 1H), 7.63–7.54 (m, 4H), 7.22 (t,
1H, J = 7.7 Hz), 5.51 (dd, 1H, J = 10.9, 5.8 Hz), 3.87
(dd, 1H, J = 16.0, 10.9 Hz), 3.75 (dd, 1H, J = 16.0,
5.8 Hz); 13C NMR (CDCl3, 100 MHz) d 170.5, 153.0,
134.6, 134.0, 133.0, 128.0, 126.2, 126.1, 124.5, 123.0,
122.4, 122.3, 122.2, 120.4, 120.1, 119.9, 119.5, 118.4,
81.0, 34.9.
5-Chloro-2,3-dihydronaphtho[1,2-b]furan-2-carboxylic acid
N-(4-chlorophenyl)amide (2d) Yield 24.8 %; m. p. 147.8–
154.3 °C; IR 3249, 1669, 1185, 757, 669 cm-1; MS(ESI)
m/z 380.0 (M ? Na?); 1H NMR (MeOD, 400 MHz) d
8.19–8.16 (m, 2H), 7.75 (s, 1H), 7.65 (d, 2H, J = 9.0 Hz),
7.63-7.59 (m, 2H), 7.34 (d, 2H, J = 9.0 Hz), 5.55 (dd, 1H,
J = 10.6, 7.3 Hz), 3.81 (dd, 1H, J = 16.1, 10.6 Hz), 3.68
(dd, 1H, J = 16.1, 7.3 Hz); 13C NMR (CDCl3, 100 MHz)
d 169.4, 153.1, 135.2, 131.9, 130.0, 129.1, 127.8, 127.6,
126.9, 126.4, 121.3, 121.1, 119.6, 119.0, 114.8, 81.3, 34.7.
5-Chloro-2,3-dihydronaphtho[1,2-b]furan-2-carboxylic acid
N-(4-trifluoromethylphenyl)amide (2i) Yield 27.6 %; m.
p. 156.8–162.5 °C; IR 3275, 1698, 1122, 1118, 763,
683 cm-1; MS(ESI) m/z 413.3 (M ? Na?); 1H NMR
(CDCl3, 400 MHz) d 8.25 (m, 1H), 8.07 (m, 1H), 7.68 (d,
1H, J = 8.2 Hz), 7.48 (s, 1H), 5.20 (dd, 1H, J = 10.9,
6.5 Hz), 3.87 (dd, 1H, J = 16.0, 10.9 Hz), 3.72 (dd, 1H,
J = 16.0, 6.5 Hz); 13C NMR (CDCl3, 100 MHz) d 170.3,
153.0, 139.8, 134.0, 128.3, 127.6, 126.4, 126.3, 126.2,
126.1, 122.6, 122.3, 120.6, 120.4, 119.7, 118.7, 81.4, 35.0.
5-Chloro-2,3-dihydronaphtho[1,2-b]furan-2-carboxylic acid
N-(3,4-dichlorophenyl)amide (2e) Yield 34.6 %; m.
p. 184.9–188.3 °C; IR 3313, 1684, 1186, 738, 669 cm-1
;
MS(ESI) m/z 416.4 (M ? Na?); 1H NMR (CDCl3,
400 MHz) d 8.25 (m, 1H), 8.05 (m, 1H), 7.79 (s, 1H),
7.64–7.61 (m, 2H), 7.37–7.36 (d, 2H, J = 1.4 Hz), 5.48
(dd, 1H, J = 10.9, 6.5 Hz), 3.85 (dd, 1H, J = 16.0,
11.0 Hz), 3.70 (dd, 1H, J = 16.0, 6.5 Hz); 13C NMR
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