The Journal of Organic Chemistry
Article
MHz, CDCl3) δ 7.48 (d, J = 2.0 Hz, 1H), 7.39 (d, J = 8.0 Hz, 1H),
7.21 (dd, J = 8.0, 2.0 Hz, 1H), 6.80 (d, J = 8.0 Hz, 1H), 6.77 (d, J =
8.0 Hz, 1H), 6.69 (s, 1H), 6.29 (d, J = 7.3 Hz, 1H), 6.23 (d, J = 7.3
Hz, 1H), 2.31 (s, 1H); 13C{1H} NMR (150 MHz, CDCl3) δ 160.3,
158.8, 142.4, 131.4, 126.6, 126.4, 126.2, 125.8, 122.5, 121.3, 112.0,
111.5, 87.4, 86.2, 21.9; 19F NMR (471 MHz, CDCl3) δ −137.0;
HRMS (ESI) m/z [M − H]− calcd for C15H10FO2− 241.0670, found
241.0661.
2,3,4b,9b-Tetrahydro-1H-indeno[5′,6′:4,5]furo[3,2-b]benzofuran
(2ac). The inseparable product was obtained as a 5:3 mixture of 2ac
and 2a after column chromatography on silica gel (petroleum ether/
ethyl acetate, 80:1, v/v) as a white amorphous powder (29.9 mg, 15%
yield): IR (KBr) 2926, 1601, 1479, 1464, 1325, 1173, 948, 743 cm−1;
1H NMR (600 MHz, CDCl3) δ 7.52 (d, J = 8.0 Hz, 1H), 7.35 (s, 1H),
7.26 (td, J = 8.0, 2.0 Hz, 1H), 6.97 (dd, J = 8.0, 2.0 Hz, 1H), 6.85 (d, J
= 8.0 Hz, 2H), 6.72 (s, 1H), 6.28 (d, J = 7.3 Hz, 1H), 6.24 (d, J = 7.3
Hz, 1H), 2.86−2.80 (m, 4H), 2.10−2.03 (m, 2H); 13C{1H} NMR
(150 MHz, CDCl3) δ 159.2, 148.6, 137.3, 131.4, 126.6, 124.8, 124.5,
122.5, 121.8, 121.2, 110.9, 106.9, 86.9, 86.8, 33.3, 32.1, 26.3; HRMS
(ESI) m/z [M + H]+ calcd for C17H15O2+ 251.1067, found 251.1067.
7a,12a-Dihydronaphtho[1′,2′:4,5]furo[3,2-b]benzofuran (2ad).
The product was obtained by flash column chromatography on silica
gel (petroleum ether/ethyl acetate, 60:1, v/v) as a white amorphous
powder (54.6 mg, 42% yield): IR (KBr) 2927, 1589, 1481, 1311,
1246, 1165, 958, 806, 752 cm−1; 1H NMR (500 MHz, CDCl3) δ 8.01
(d, J = 8.0 Hz, 1H), 7.79 (t, J = 8.0 Hz, 2H), 7.57 (d, J = 8.0 Hz, 2H),
7.37 (d, J = 8.0 Hz, 1H), 7.26 (t, J = 8.0 Hz, 1H), 7.11 (d, J = 8.0 Hz,
1H), 6.97 (t, J = 8.0 Hz, 1H), 6.86 (d, J = 8.0 Hz, 1H), 6.72 (d, J = 8.0
Hz, 1H), 6.45 (d, J = 8.0 Hz, 1H); 13C{1H} NMR (125 MHz,
CDCl3) δ 160.2, 158.4, 132.7, 131.6, 131.1, 129.6, 128.9, 127.9, 126.7,
124.6, 123.8, 122.6, 121.2, 112.8, 111.1, 87.5, 86.5; HRMS (ESI) m/z
1,7-Difluoro-4b,9b-dihydrobenzofuro[3,2-b]benzofuran (2x).
The product was obtained by flash column chromatography on silica
gel (petroleum ether/ethyl acetate, 80:1, v/v) as a white amorphous
powder (51.7 mg, 42% yield): IR (KBr) 2924, 1616, 1494, 1454,
1
1325, 1265, 1193, 1043, 964, 842, 765 cm−1; H NMR (600 MHz,
CDCl3) δ 7.51 (d, J = 8.0 Hz, 1H), 7.30 (d, J = 8.0 Hz, 1H), 7.07 (t, J
= 8.0 Hz, 1H), 6.93 (td, J = 8.0, 2.0 Hz, 1H), 6.70 (td, J = 8.0, 2.0 Hz,
1H), 6.58 (dd, J = 8.0, 2.0 Hz, 1H), 6.37 (d, J = 7.3 Hz, 1H), 6.35 (d,
J = 7.3 Hz, 1H); 13C{1H} NMR (150 MHz, CDCl3) δ 166.2, 164.5,
161.6, 161.5, 148.9, 147.2, 147.2, 147.1, 127.7, 127.7, 127.7, 127.7,
122.1, 122.1, 121.9, 121.9, 119.9, 119.9, 118.4, 118.3, 108.9, 108.8,
99.2, 99.0, 87.9, 87.9, 87.4; 19F NMR (471 MHz, CDCl3) δ −108.6,
−136.8; HRMS (ESI) m/z [M + H]+ calcd for C14H9F2O2+ 247.0565,
found 247.0569.
8-Chloro-2-methyl-4b,9b-dihydrobenzofuro[3,2-b]benzofuran
(2y). The product was obtained by flash column chromatography on
silica gel (petroleum ether/ethyl acetate, 80:1, v/v) as a white
amorphous powder (74.8 mg, 58% yield): IR (KBr) 2916, 1608, 1429,
1323, 1240, 1172, 1112, 954, 798 cm−1; 1H NMR (600 MHz, CDCl3)
δ 7.48 (d, J = 2.0 Hz, 1H), 7.39 (d, J = 8.0 Hz, 1H), 7.21 (dd, J = 8.0,
2.0 Hz, 1H), 6.80 (d, J = 8.0 Hz, 1H), 6.77 (d, J = 8.0 Hz, 1H), 6.69
(s, 1H), 6.29 (d, J = 7.3 Hz, 1H), 6.22 (d, J = 7.3 Hz, 1H), 2.33 (s,
3H); 13C{1H} NMR (150 MHz, CDCl3) δ 160.3, 158.8, 142.4, 131.4,
126.6, 126.4, 126.2, 125.8, 122.5, 121.3, 112.0, 111.5, 87.4, 86.2, 21.9;
HRMS (ESI) m/z [M − H]− calcd for C15H10ClO2− 257.0375, found
257.0367.
−
[M − H]− calcd for C18H11O2 259.0765, found 259.0762.
9-(tert-Butyl)-7a,12a-dihydronaphtho[1′,2′:4,5]furo[3,2-b]-
benzofuran (2ae). The product was obtained by flash column
chromatography on silica gel (petroleum ether/ethyl acetate, 60:1, v/
v) as a white amorphous powder (61.6 mg, 39% yield): IR (KBr)
2958, 1625, 1583, 1489, 1460, 1367, 1224, 1165, 1068, 956, 808, 740
cm−1; 1H NMR (600 MHz, CDCl3) δ 8.03 (d, J = 8.0 Hz, 1H), 7.83
(d, J = 8.0 Hz, 1H), 7.81 (d, J = 8.0 Hz, 1H), 7.61 (d, J = 2.0 Hz, 1H),
7.59 (dd, J = 8.0 Hz, 1H), 7.39 (t, J = 8.0 Hz, 1H), 7.33 (dd, J = 8.0,
2.0 Hz, 1H), 7.14 (d, J = 8.0 Hz, 1H), 6.83 (d, J = 8.0 Hz, 1H), 6.73
(d, J = 7.5 Hz, 1H), 6.47 (d, J = 5.5 Hz, 1H), 1.33 (s, 9H); 13C{1H}
NMR (150 MHz, CDCl3) δ 158.4, 158.0, 144.4, 132.6, 131.1, 129.6,
128.9, 128.8, 127.9, 124.1, 123.7, 123.2, 122.7, 116.5, 112.8, 110.4,
87.8, 86.7, 34.6, 31.8, 31.8, 31.8; HRMS (ESI) m/z [M − H]− calcd
8-Isopropyl-4b,9b-dihydrobenzofuro[3,2-b]benzofuran-2-car-
bonitrile (2z). The product was obtained by flash column
chromatography on silica gel (petroleum ether/ethyl acetate, 80:1,
v/v) as a white solid (92.8 mg, 67% yield): mp 155−157 °C; IR
(KBr) 2962, 2229, 1616, 1490, 1425, 1348, 1255, 1197, 1118, 960,
−
for C22H19O2 315.1391, found 315.1380.
7a,12a-Dihydronaphtho[1′,2′:4,5]furo[3,2-b]benzofuran-10-car-
bonitrile (2af). The product was obtained by flash column
chromatography on silica gel (petroleum ether/ethyl acetate, 60:1,
v/v) as a white solid (62.7 mg, 44% yield): mp 211−213 °C; IR
(KBr) 2927, 2231, 1589, 1481, 1311, 1246, 1165, 958, 806, 752 cm−1;
1H NMR (600 MHz, CDCl3) δ 8.00 (d, J = 8.0 Hz, 1H), 7.8t (t, J =
1
831, 630 cm−1; H NMR (600 MHz, CDCl3) δ 7.61 (d, J = 8.0 Hz,
1H), 7.39 (d, J = 2.0 Hz, 1H), 7.26 (dd, J = 8.0, 2.0 Hz, 1H), 7.18
(dd, J = 8.0, 2.0 Hz, 1H), 7.11 (s, 1H), 6.80 (d, J = 8.0 Hz, 1H), 6.37
(d, J = 7.4 Hz, 1H), 6.26 (d, J = 7.4 Hz, 1H), 2.90 (hept, J = 6.9 Hz,
1H), 1.24 (d, J = 6.9 Hz, 6H); 13C{1H} NMR (150 MHz, CDCl3) δ
160.1, 158.0, 142.7, 130.3, 130.1, 127.6, 125.4, 124.2, 123.4, 118.6,
114.7, 114.5, 110.7, 87.9, 85.4, 33.7, 24.5, 24.3; HRMS (ESI) m/z [M
8.0 Hz, 2H), 7.67 (d, J = 8.0 Hz, 1H), 7.62 (t, J = 8.0 Hz, 1H), 7.42
(t, J = 8.0 Hz, 1H), 7.28 (t, J = 8.0 Hz, 1H), 7.13 (d, J = 8.0 Hz, 2H),
6.85 (d, J = 7.6 Hz, 1H), 6.47 (d, J = 7.6 Hz, 1H); 13C{1H} NMR
(150 MHz, CDCl3) δ 160.2, 158.3, 133.3, 130.9, 130.0, 129.7, 129.0,
128.2, 127.7, 125.4, 124.2, 122.5, 118.6, 115.5, 114.8, 114.7, 112.6,
−
− H]− calcd for C18H14NO2 276.1030, found 276.1031.
8-Chloro-4b,9b-dihydrobenzofuro[3,2-b]benzofuran-2-carboni-
trile (2aa). The product was obtained by flash column chromatog-
raphy on silica gel (petroleum ether/ethyl acetate, 60:1, v/v) as a
white amorphous powder (64.6 mg, 48% yield): IR (KBr) 2980, 2233,
−
87.7, 86.1; HRMS (ESI) m/z [M − H]− calcd for C19H10NO2
284.0717, found 284.0709.
1
1608, 1477, 1423, 1321, 1238, 1168, 1114, 970, 821 cm−1; H NMR
9-Isopropyl-7a,12a-dihydronaphtho[1′,2′:4,5]furo[3,2-b]-
benzofuran (2ag). The product was obtained by flash column
chromatography on silica gel (petroleum ether/ethyl acetate, 60:1, v/
v) as a white amorphous powder (58.9 mg, 39% yield): IR (KBr)
(600 MHz, CDCl3) δ 7.61 (d, J = 8.0 Hz, 1H), 7.50 (d, J = 2.0 Hz,
1H), 7.29 (dd, J = 8.0, 2.0 Hz, 1H), 7.26 (dd, J = 8.0, 2.0 Hz, 1H),
7.13 (s, 1H), 6.81 (d, J = 8.0 Hz, 1H), 6.35 (d, J = 7.4 Hz, 1H), 6.32
(d, J = 7.4 Hz, 1H); 13C{1H} NMR (150 MHz, CDCl3) δ 159.9,
158.5, 131.9, 129.5, 127.7, 126.7, 126.5, 125.7, 125.3, 118.4, 115.0,
114.6, 112.2, 87.0, 86.1; HRMS (ESI) m/z [M − H]− calcd for
1
2958, 1625, 1490, 1456, 1240, 1161, 1118, 956, 808, 742 cm−1; H
NMR (600 MHz, CDCl3) δ 8.02 (t, J = 8.0 Hz, 1H), 7.83 (d, J = 8.0
Hz, 1H), 7.80 (d, J = 8.0 Hz, 1H), 7.59 (t, J = 8.0 Hz, 1H), 7.45 (d, J
= 2.0 Hz, 1H), 7.38 (t, J = 8.0 Hz, 1H), 7.18−7.12 (overlapped, 2H),
6.81 (d, J = 8.0 Hz, 1H), 6.73 (d, J = 7.5 Hz, 1H), 6.46 (d, J = 7.5 Hz,
1H), 2.90 (hept, J = 6.9 Hz, 1H), 1.25 (d, J = 6.9 Hz, 6H); 13C{1H}
NMR (150 MHz, CDCl3) δ 158.2, 158.2, 141.9, 132.5, 131.0, 129.7,
129.4, 128.7, 127.7, 124.2, 124.0, 124.0, 123.6, 122.5, 116.3, 112.7,
110.6, 87.6, 86.4, 33.6, 24.4, 24.2; HRMS (ESI) m/z [M − H]− calcd
−
C15H7ClNO2 268.0171, found 268.0162.
4b,9b-Dihydrobenzofuro[3,2-b]benzofuran-1-ol (2ab). The
product was obtained by flash column chromatography on silica gel
(petroleum ether/ethyl acetate, 6:1, v/v) as a white amorphous
powder (28.3 mg, 25% yield): IR (KBr) 2935, 1618, 1460, 1373,
1
1222, 1174, 1109, 962, 756 cm−1; H NMR (600 MHz, CDCl3) δ
−
7.54 (d, J = 8.0 Hz, 1H), 7.30 (td, J = 8.0, 2.0 Hz, 1H), 7.11 (dd, J =
8.0, 2.0 Hz, 1H), 6.98 (t, J = 8.0 Hz, 1H), 6.90−6.86 (m, 3H), 6.36
(d, J = 7.2 Hz, 1H), 6.32 (d, J = 7.2 Hz, 1H); 13C{1H} NMR (150
MHz, CDCl3) δ 160.2, 147.4, 140.9, 131.7, 126.7, 125.4, 124.2, 122.4,
121.3, 118.2, 117.6, 111.1, 87.6, 87.2; HRMS (ESI) m/z [M + H]+
for C21H17O2 301.1234, found 301.1234.
9-Chloro-7a,12a-dihydronaphtho[1′,2′:4,5]furo[3,2-b]-
benzofuran (2ah). The product was obtained by flash column
chromatography on silica gel (petroleum ether/ethyl acetate, 60:1, v/
v) as a white amorphous powder (54.4 mg, 37% yield): IR (KBr)
2922, 1625, 1593, 1500, 1460, 1319, 1244, 1197, 1041, 945, 804, 736
+
calcd for C14H11O3 227.0703, found 227.0713.
L
J. Org. Chem. XXXX, XXX, XXX−XXX