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S. N. Joshi et al.
PAPER
2,2¢,3,4¢,6-Pentachloro-5-methoxybiphenyl (17a)
Colorless solid; mp 118–120 °C (CHCl3–MeOH); Rf = 0.39 (hex-
ane–EtOAc, 9:1).
Anal. Calcd for C14H9Cl5O2: C, 43.51; H, 2.35. Found: C, 43.74; H,
2.26.
2,2¢,3,5¢,6-Pentachloro-4,5-dimethoxybiphenyl (18b)
Colorless oil; Rf = 0.44 (hexane–EtOAc, 9:1).
1H NMR (400 MHz, CDCl3): d = 3.95 (s, 3 H, OCH3), 4.00 (s, 3 H,
OCH3), 7.19 (d, J = 2.4 Hz, 1 H), 7.35 (dd, J = 2.4, 8.3 Hz, 1 H),
7.44 (d, J = 8.3 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 61.22, 61.24, 127.0, 127.7, 128.5,
130.0, 130.7, 130.8, 132.1, 132.7, 133.0, 137.3, 149.4, 151.2.
1H NMR (400 MHz, CDCl3): d = 3.95 (s, 3 H, OCH3), 7.11 (d,
J = 8.2 Hz, 1 H), 7.11 (s, 1 H), 7.36 (dd, J = 2.1, 8.2 Hz, 1 H), 7.54
(d, J = 2.1 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 56.7, 113.3, 122.2, 124.5, 127.4,
129.6, 131.4, 131.7, 134.1, 134.7, 135.1, 138.3, 154.1.
MS (EI, 70 eV): m/z (%) = 354 (58, [M]+), 339 (2), 311 (16), 241
(21), 171 (9).
MS (EI, 70 eV): m/z (%) = 384 (60, [M]+), 369 (26), 341 (18), 326
(15), 228 (22).
Anal. Calcd for C13H7Cl5O: C, 43.75; H, 1.96. Found: C, 43.77; H,
1.76.
Anal. Calcd for C14H9Cl5O2: C, 43.51; H, 2.35. Found: C, 43.91; H,
2.24.
2,2¢,3,5¢,6-Pentachloro-5-methoxybiphenyl (17b)
Colorless solid; mp 40–42 °C (CHCl3–MeOH); Rf = 0.38 (hexane–
EtOAc, 9:1).
1H NMR (400 MHz, CDCl3): d = 3.95 (s, 3 H, OCH3), 7.12 (s, 1 H),
7.18 (d, J = 2.4 Hz, 1 H), 7.35 (dd, J = 2.5, 8.6 Hz, 1 H), 7.44 (d,
J = 8.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 56.7, 113.3, 122.0, 124.3, 129.9,
130.4, 130.7, 131.67, 131.74 131.8, 132.7, 137.5, 138.1, 154.1.
MS (EI, 70 eV): m/z (%) = 354 (91, [M]+), 339 (5), 311 (25), 241
(28), 171 (29).
2,2¢,3,3¢,4¢,6-Hexachloro-4,5-dimethoxybiphenyl (18c)
Colorless solid; mp 93–95 °C (CHCl3–MeOH); Rf = 0.41 (hexane–
EtOAc, 9:1).
1H NMR (300 MHz, CDCl3): d = 3.96 (s, 3 H, OCH3), 4.00 (s, 1 H,
OCH3), 7.05 (d, J = 8.3 Hz, 1 H), 7.49 (d, J = 8.3 Hz, 1 H).
13C NMR (75 MHz, CDCl3): d = 61.19, 61.22, 127.1, 127.6, 128.4,
128.6, 128.9, 132.4, 133.2, 134.0, 134.5, 136.3, 149.4, 151.3.
MS (EI, 70 eV): m/z (%) = 418 (56, [M]+), 403 (20), 375 (9), 360
(20), 262 (20).
Anal. Calcd for C13H7Cl5O: C, 43.75; H, 1.96. Found: C, 43.80; H,
1.91.
Anal. Calcd for C14H8Cl6O: C, 39.95; H, 1.92. Found: C, 40.00; H,
1.79.
2,2¢,3,3¢,4¢,6-Hexachloro-5-methoxybiphenyl (17c)
Colorless crystalline solid; mp 134–135 °C (CHCl3–MeOH);
Rf = 0.34 (hexane–EtOAc, 9:1).
1H NMR (300 MHz, CDCl3): d = 3.95 (s, 3 H, OCH3), 7.03 (d,
J = 8.3 Hz, 1 H), 7.12 (s, 1 H), 7.50 (d, J = 8.3 Hz, 1 H).
13C NMR (75 MHz, CDCl3): d = 56.7, 113.4, 122.0, 124.2, 128.6,
131.9, 132.4, 133.6, 134.4, 136.4, 138.4, 154.2.
Demethylation Reaction; General Procedure
BBr3 (1 M in hexane, 5 equiv) was added to a solution of the meth-
oxylated biphenyl 16, 17 (0.3 mmol) in anhyd CH2Cl2 (5 mL) under
N2.33 The reaction mixture was stirred at r.t. for 14 h, cooled with
ice/salt, and hydrolyzed with an equal volume of ice-cold H2O. The
aqueous phase was extracted with CH2Cl2 (2 × 50 mL). The com-
bined organic layers were washed with H2O (3 × 25 mL), dried
(MgSO4), and the solvent was removed under reduced pressure. The
product was purified by column chromatography on silica gel with
hexane–EtOAc (1:1, v/v) as eluent, followed by recrystallization
from MeOH–CHCl3 (3:1, v/v), to give the corresponding hydroxy
compounds as white solids or colorless oils in 50–55% yield.
MS (EI, 70 eV): m/z (%) = 388 (44, [M]+), 345 (14), 275 (8), 205
(8).
Anal. Calcd for C13H6Cl6O: C, 39.94; H, 1.55. Found: C, 40.20; H,
1.44.
2,2¢,3,4¢,5¢,6-Hexachloro-5-methoxybiphenyl (17d)
Colorless solid; yield: 43%; mp 91–92 °C (CHCl3–MeOH);
Rf = 0.39 (hexane–EtOAc, 9:1).
1H NMR (300 MHz, CDCl3): d = 3.95 (s, 3 H, OCH3), 7.13 (s, 1 H),
7.29 (s, 1 H), 7.64 (s, 1 H).
13C NMR (75 MHz, CDCl3): d = 56.7, 113.6, 122.1, 124.3, 131.0,
131.4, 131.8, 131.9, 132.3, 133.6, 135.8, 137.2, 154.3.
MS (EI, 70 eV): m/z (%) = 388 (47, [M]+), 345 (16), 338 (12), 275
(23), 205 (12).
2,2¢,3,4¢,6-Pentachlorobiphenyl-4-ol (19a)
Colorless oil; yield: 62%; Rf = 0.21 (hexane–EtOAc, 9:1).
1H NMR (300 MHz, CDCl3): d = 5.85 (br s, 3 H, OH), 7.12 (d,
J = 8.2 Hz, 1 H), 7.16 (s, 1 H), 7.35 (dd, J = 2.5, 8.6 Hz, 1 H), 7.53
(d, J = 8.6 Hz, 1 H).
13C NMR (75 MHz, CDCl3): d = 115.4, 118.5, 127.4, 129.6, 129.8,
132.2, 133.4, 133.8, 134.4, 135.0, 135.2, 152.4.
MS (EI, 70 eV): m/z (%) = 340 (60, [M]+), 270 (31), 241 (11), 171
(20).
Anal. Calcd for C13H6Cl6O: C, 39.92; H, 1.55. Found: C, 40.09; H,
1.27.
HRMS: m/z [M – H]+ calcd for C12H4Cl5O: 338.8705; found:
338.8705.
2,2¢,3,4¢,6-Pentachloro-4,5-dimethoxybiphenyl (18a)
Colorless solid; mp 70–72 °C (CHCl3–MeOH); Rf = 0.42 (hexane–
EtOAc, 9:1).
1H NMR (400 MHz, CDCl3): d = 3.95 (s, 3 H, OCH3), 4.00 (s, 3 H,
OCH3), 7.12 (d, J = 8.3 Hz, 1 H), 7.35 (dd, J = 8.3, 2.1 Hz, 1 H),
7.54 (d, J = 2.1 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 61.22, 61.24, 127.0, 127.4, 127.8,
128.6, 129.6, 131.7, 133.2, 134.5, 135.2, 149.4, 151.2.
MS (EI, 70 eV): m/z (%) = 384 (64, [M]+), 369 (24), 341 (18), 326
(20), 228 (20).
2,2¢,3,5¢,6-Pentachlorobiphenyl-4-ol (19b)
Colorless oil; yield: 47%; Rf = 0.18 (hexane–EtOAc, 9:1).
1H NMR (300 MHz, CDCl3): d = 5.90 (br s, 3 H, OH), 7.16 (s, 1 H),
7.20 (d, J = 2.5 Hz, 1 H), 7.36 (dd, J = 2.5, 8.6 Hz, 1 H), 7.45 (d,
J = 8.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 115.4, 118.5, 129.6, 130.0, 130.6,
131.2, 132.5, 132.6, 133.2, 133.6, 137.2, 152.4.
MS (EI, 70 eV): m/z (%) = 340 (68, [M]+), 270 (345), 241 (11), 171
(20).
Synthesis 2011, No. 7, 1045–1054 © Thieme Stuttgart · New York