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Helvetica Chimica Acta – Vol. 95 (2012)
2-Bromo-3’,4’-dimethoxy-1,1’-biphenyl (8). To a Schlenk flask (1000 ml) were added 1,2-dibromo-
benzene (12.0 g, 66.0 mmol), 7 (19.5 g, 82.5 mmol), Pd(PPh3)4 (3.81 g, 3.3 mmol), toluene (300 ml),
EtOH (200 ml), and Na2CO3 soln. (100 ml, 2.5m, 250 mmol). The mixture was degassed and refilled with
Ar three times. The mixture was heated at reflux for 24 h. After cooling to r.t., the mixture was diluted
with H2O (300 ml), and the aq. layer was extracted with CH2Cl2 (3 ꢂ 200 ml). The combined org. solvent
was washed with brine (200 ml), dried (Na2SO4), and concentrated in vacuo. The residue was purified by
1
FC (CH2Cl2/hexane 1:3) to give 8 (16.2 g, 84%). Pale yellow oil. H-NMR (300 MHz, CDCl3): 7.66 (d,
J ¼ 8.1, 1 H); 7.32 – 7.33 (m, 2 H); 7.21 – 7.15 (m, 1 H); 6.97 – 6.91 (m, 3 H); 3.92 (s, 3 H); 3.90 (s, 3 H). EI-
MS: 294 ([M(81Br)]þ, 99), 292 ([M(79Br)]þ,100); 277 (22), 279 (21), 170 (58), 152 (31), 139 (33), 127
(72).
2,2’-Dibromo-3’,4’-dimethoxy-1,1’-biphenyl (4). To a soln. of 8 (18.0 g, 62 mmol) in AcOH (100 ml)
was added Br2 (3.75 ml, 73.5 mmol) at r.t. The resulting mixture was stirred overnight before quenching
the reaction with Na2SO3 soln. (50 ml). The aq. layer was extracted with CH2Cl2 (3 ꢂ 200 ml). The
combined org. layer was washed with brine (200 ml), dried (Na2SO4), and concentrated in vacuo. The
residue was purified by FC (CH2Cl2/hexane 1:3) to afford 4 (21.2 g, 92%). White solid. M.p. 111 – 1148
([26]: 109.9 – 110.88). 1H-NMR (300 MHz, CDCl3): 7.67 (d, J ¼ 8.1, 1 H); 7.38 (t, J ¼ 7.2, 1 H); 7.29 – 7.23
(m, 2 H); 7.12 (s, 1 H); 6.75 (s, 1 H); 3.93 (s, 3 H); 3.86 (s, 3 H). EI-MS: 374 ([M(81Br 81Br)]þ, 54), 372
([M(81Br 79Br)]þ, 100), 370 ([M(79Br 79Br)]þ, 52), 357 (11), 293 (10), 291 (9), 248 (17), 126 (32).
2,3,10,11-Tetramethoxy- and 2,3,6,7-Tetramethoxytetraphenylene (10 and 11, resp.). To a soln. of 4
(3.72 g, 10 mmol) in THF (90 ml) was added a 2.5m hexane soln. of BuLi (10 ml, 25 mmol) dropwise at
ꢀ 788, and the mixture was stirred for 4 h at ꢀ 788. Then, anh. CuCl2 (4.03 g, 30 mmol) was added. After
stirring for 2 h at ꢀ 788, the mixture was allowed to warm to r.t. and stirred overnight. The reaction was
quenched with NH3 · H2O (2n, 150 ml). The org. layer was then separated, and the aq. layer was extracted
with CH2Cl2 (3 ꢂ 200 ml). The combined org. extracts were washed with NaHSO3 (2m; 150 ml), brine
(2 ꢂ 200 ml), dried (Na2SO4), filtered, and concentrated under reduced pressure. FC (AcOEt/CH2Cl2/
hexane 1:2 :8) gave a mixture 10/11. Then, 10/11 was subjected to successive FC (AcOEt/CH2Cl2/hexane
1:10 :15) afforded pure 10 and 11, resp.
The less polar compound was 11 (440 mg, 21%). White solid. M.p. 262 – 2648. IR: 3445, 3055, 2994,
2933, 2844, 1602, 1510, 1479, 1462, 1436, 1395, 1383, 1333, 1320, 1256, 1233, 1202, 1170, 1154, 1051, 1025,
861, 762,748, 597. 1H-NMR (300 MHz, CDCl3): 7.32 – 7.26 (m, 4 H); 7.21 – 7.15 (m, 4 H); 6.68 (s, 2 H); 6.67
(s, 2 H); 3.85 (s, 6 H); 3.84 (s, 6 H). 13C-NMR (100 MHz, CDCl3): 147.9; 147.8; 142.0; 141.6; 134.0; 133.7;
129.24; 129.17; 127.2; 127.1; 112.3; 112.2; 55.94; 55.88. EI-MS: 424 (Mþ, 100), 425 (33), 409 (5), 366 (9),
335 (12), 85 (5), 71 (4), 57 (9). HR-MS: 424.1673 (Mþ, C28H24O4þ ; calc. 424.1675).
The more polar compound was 10 (236 mg, 11%). White solid. M.p. 219 – 2228. 1H-NMR (300 MHz,
CDCl3): 7.29 – 7.24 (m, 4 H); 7.22 – 7.16 (m, 4 H); 6.69 (s, 4 H); 3.86 (s, 12 H). 13C-NMR (100 MHz,
CDCl3): 147.8; 141.5; 133.9; 129.2; 127.0; 112.1; 55.8. IR: 3445, 3060, 3015,2991, 2955, 2932, 2844, 1735,
1606, 1539, 1516, 1483, 1463, 1434, 1383, 1353, 1259, 1235, 1204, 1184, 1166, 1049, 1025, 859, 817, 772, 757,
738, 639, 608, 567. EI-MS: 424 (Mþ, 100), 425 (33), 409 (5), 366 (9), 335 (12), 85 (5), 71 (4), 57 (9). HR-
MS: 424.1671 (Mþ, C28H24Oþ4 ; calc. 424.1675).
Tetraphenylene-2,3,10,11-tetrol (1). To a vigorously stirred suspension of 10 (424 mg, 1 mmol) in
CH2Cl2 (100 ml) at 08 was added a 1.0m soln. of BBr3 in CH2Cl2 (10 ml, 10 mmol) slowly. The mixture was
stirred overnight at r.t., and a clear brownish-red soln. was obtained. The mixture was hydrolyzed by
careful addition of cold H2O (10 ml), and the white solid precipitated was dissolved by addition of
AcOEt (100 ml). The org. layer was separated, and the aq. layer was extracted with AcOEt (2 ꢂ 50 ml).
The combined org. extract was dried (Na2SO4) and evaporated under reduced pressure. The residue was
purified by FC (hexane/AcOEt 1:1) to give 1 (411 mg, 98%). Air- and moisture-sensitive white solid.
M.p. 356 – 3628. IR: 3494, 3364, 3273, 3057, 1606, 1522, 1486, 1448, 1423, 1355, 1292, 1272, 1240, 1224,
1211, 1190, 1159, 891, 878, 868, 830, 767, 633, 579, 568. 1H-NMR (300 MHz, CD3COCD3): 7.97 (br., 4 H);
7.23 – 7.20 (m, 4 H); 7.11 – 7.08 (m, 4 H); 6.62 (s, 4 H). 13C-NMR (100 MHz, CD3OD): 145.6; 143.6; 135.4;
130.3; 127.9; 117.3. ESI-MS: 367 ([M ꢀ H]ꢀ), 403 ([M þ C2H5OH ꢀ H]ꢀ). HR-MS: 391.09475 ([M þ
Na]þ, C28H24NaOþ4 ; calc. 391.09408.
Tetraphenylene-2,3,6,7-tetrol (12). To a soln. of 10/11 (551 mg, 1.3 mmol) in CH2Cl2 (150 ml) at 08
was added a 1.0m soln. of BBr3 in CH2Cl2 (12 ml, 12 mmol) slowly. The mixture was stirred overnight at