Substituent Effects on the Long Bond Length
J . Org. Chem., Vol. 65, No. 16, 2000 4947
mmol) in dry THF (20 mL) was added dropwise n-BuLi (1.47
mol dm-3 in n-hexane, 7.10 mL, 10.4 mmol) at 0 °C under Ar,
and the mixture was stirred for 10 min at this temperature.
To the resultant suspension of 2,2′-dilithiobiphenyl was added
a mixture of 4,4′-bis(dimethylamino)benzophenone (1.30 g, 4.85
mmol) and xanthone (971 mg, 4.95 mmol) in dry THF (90 mL).
After stirring for 2 h at room temperature, the reaction was
quenched by adding water. THF was evaporated, and the
residue was extracted with benzene. The organic layer was
washed with water and brine and dried over Na2SO4. Evapo-
ration of the solvent gave 3.66 g of oily material containing
9-[2′-bis(4-dimethylaminophenyl)hydroxymethylbiphenyl-2-yl]-
9-hydroxyxanthene 5. Two symmetric diols, biphenyl-2,2′-
diylbis(9-hydroxyxanthene) 5′ and 2,2′-bis[bis(4-dimethylami-
nophenyl)hydroxymethyl]biphenyl 5′′,24 were also formed in
this reaction. Chromatographic separation on SiO2 (AcOEt/n-
hexane, 1/4-1/2) followed by recrystallization from MeOH gave
5 as colorless crystals (250 mg, yield 8.6%). An authentic
sample of 5′ was prepared by the similar reaction of 2,2′-
dilithiobiphenyl with 2 equiv of xanthone (62% yield).
To a solution of unsymmetric diol 5 (70 mg, 0.11 mmol) in
DME (3 mL) was added propionic anhydride (0.5 mL) followed
by 42% HBF4 (50 µL, 0.34 mmol), and the mixture was heated
at 80 °C for 1 h. By slow cooling to room temperature, dication
salt 62+(BF4-)2 separated as a deep-green solid (80 mg, yield
93%), which was filtered, washed with DME, and dried in
vacuo.
To a suspension of 62+(BF4-)2 (30 mg, 0.040 mmol) in dry
THF (10 mL) was added SmI2 (0.1 mol dm-3 in THF, 1.7 mL,
0.17 mmol) at room temperature. The deeply colored suspen-
sion gradually turned colorless during the addition. After
stirring for 30 min and evaporation of THF, the residue was
suspended in water and extracted with CH2Cl2. The organic
layer was washed with water and brine and dried over Na2-
SO4. Evaporation of solvent followed by separation by prepara-
tive TLC (SiO2, AcOEt/n-hexane, 1/4) gave HPE derivative 1
as colorless crystals (18 mg, yield 78%).
Data of 5: mp 143-152 °C (dec); 1H NMR (400 MHz, CDCl3,
24 °C) δ/ppm 7.63 (1H, dd, J ) 7.8, 1.5 Hz), 7.39 (1H, dd, J )
7.8, 1.5 Hz), 7.32 (1H, ddd, J ) 7.8, 7.8, 1.5 Hz), 7.10-7.24
(6H, m), 7.02 (AA′XX′, 2H), 6.95-7.00 (2H, m), 6.86 (AA′XX′,
2H), 6.83-6.92 (3H, m), 6.72 (1H, ddd, J ) 7.8, 7.8, 1.5 Hz),
6.64 (AA′XX′, 2H), 6.59 (AA′XX′, 2H), 6.18 (1H, dd, J ) 7.8,
1.5 Hz), 5.72 (1H, s), 3.02 (1H, s), 2.94 (6H, s), 2.93 (6H, s); IR
(KBr) 3432, 1612, 1520, 1478, 1450, 758 cm-1; FD-MS m/z 618
(M+, BP). Anal. Calcd for C42H38N2O3: C, 81.53; H, 6.19; N,
4.53. Found: C, 81.60; H, 6.19; N, 4.40. Data of 5′: colorless
solid, mp 128-133 °C (dec); 1H NMR (400 MHz, CDCl3, 24
°C) δ/ppm 7.64 (2H, dd, J ) 8.0, 1.5 Hz), 7.34 (2H, ddd, J )
8.0, 8.0, 1.5 Hz), 7.22-7.30 (6H, m), 7.04-7.20 (10H, m), 6.98
(2H, ddd, J ) 8.0, 8.0, 1.5 Hz), 6.82 (2H, dd, J ) 8.0, 1.5 Hz);
IR (KBr) 3420, 1478, 1450, 1240, 756 cm-1; EI-MS m/z (relative
intensity) 528 (M+ - H2O, 100), 512 (21), 331 (84). Anal. Calcd
for C38H26O4: C, 83.50; H, 4.79. Found: C, 83.39; H, 4.86. Data
of 62+(BF4-)2: mp 219-220 °C (dec); 1H NMR (400 MHz, CD3-
CN, 50 °C) δ/ppm 8.40 (2H, br), 8.23 (2H, br d, J ) 8.5 Hz),
7.90 (2H, br d, J ) 8.5 Hz), 7.78-7.84 (3H, br m), 7.46-7.56
(3H, br m), 7.32 (2H, ddd, J ) 7.8, 7.8, 1.0 Hz), 7.26-7.30 (1H,
br m), 6.85 (2H, br d, J ) 7.8 Hz), 6.20-7.20 (7H, br), 3.30
(6H, br s), 3.29 (6H, br s); IR (KBr) 1620, 1584, 1374, 1174,
1084, 1036 cm-1; FAB-MS m/z (relative intensity) 584 (M+,
100), 671 (M+ + BF4, 8). Anal. Calcd for C42H36N2OB2F8: C,
66.52; H, 4.78; N, 3.69. Found: C, 66.64; H, 4.79; N, 3.76. Data
of 1: mp 294-295 °C (dec); 1H NMR (400 MHz, CDCl3, 24 °C)
δ/ppm 8.03 (1H, d, J ) 7.5 Hz), 7.90 (1H, d, J ) 7.5 Hz), 7.46
(1H, ddd, J ) 7.5, 7.5, 1.5 Hz), 7.34 (1H, dd, J ) 7.8, 1.5 Hz),
7.22-7.30 (3H, m), 7.13-7.19 (2H, m), 6.88-7.04 (3H, m),
6.63-6.72 (6H, m), 6.61 (2H, dd, J ) 8.3, 1.5 Hz), 6.24 (4H,
AA′XX′), 2.84 (12H, s); IR (KBr) 1610, 1518, 1480, 1440, 1312,
750 cm-1; FD-MS m/z 584 (M+, BP); UV (MeCN) λmax 270 (log
ꢀ 4.58), 200 sh (5.00). Anal. Calcd for C42H36N2O: C, 86.27; H,
6.21; N, 4.79. Found: C, 86.04; H, 6.41; N, 4.65.
P r ep a r a tion of 9,9-Bis(4-d im eth yla m in op h en yl)-10,10-
d icya n o-9,10-d ih yd r op h en a n th r en e 2. Crystalline 2,2′-
dilithiobiphenyl‚TMEDA2 complex23 was prepared from biphe-
nyl (4.30 g, 24.0 mmol) and n-BuLi (1.43 mol dm-3 in n-hexane,
46.0 mL, 65.8 mmol) in TMEDA (10 mL). Without filtration
of the moisture-sensitive complex, supernatant was removed
using a syringe. To a THF (10 mL) solution of this solid (6.20
g) was added dropwise a mixture of 1,2-diiodoethane (6.59 g,
23.4 mmol) and DMF (4.41 g, 70.1 mmol) in dry THF (10 mL)
at -78 °C over 15 min. The temperature of the cooling bath
was gradually (overnight) raised to room temperature. After
addition of 10% Na2S2O3 aq and evaporation of THF, the
residue was extracted with CHCl3. From the extract was
obtained 6.98 g of reddish oil, which was chromatographed on
SiO2 (n-hexane; n-hexane/benzene 1/4-1/1; CHCl3). The first
eluate gave 1.59 g of 2,2′-diiodobiphenyl 4 (yield 25%), and
the second eluate gave 2-formyl-2′-iodobiphenyl as colorless
rods 7 (772 mg, yield 16% based on biphenyl). Further eluates
contained 2,2′-diformylbiphenyl 7′ and other polar byproducts.
When the similar reaction of 2,2′-dilithiobiphenyl was con-
ducted using an equimolar mixture of 1,2-diiodoethane and
DMF, the product ratio of 4:7:7′ determined by gas chroma-
tography was 20:11:2.
A mixture of 7 (200 mg, 0.649 mmol), N,N-dimethylaniline
(196 mg, 1.62 mmol), ZnCl2 (74 mg, 0.54 mmol), and urea (33
mg, 0.54 mmol) was heated at 95 °C for 4.5 h with vigorous
stirring. After being cooled, the mixture was triturated with
benzene and insoluble material was removed by filtration.
Chromatographic separation on SiO2 (n-hexane/CHCl3 1/1)
gave 2-[bis(4-dimethylaminophenyl)methyl]-2′-iodobiphenyl 8
(185 mg, yield 54%) as colorless crystals.
Mineral oil of NaH (104 mg, 60%, 1.73 mmol) was removed
by washing with n-hexane. To its suspension in dry THF (20
mL) was added malononitrile (57 mg, 0.86 mmol) at 0 °C. After
gas evolution ceased, iodide 8 (90 mg, 0.17 mmol) and (Ph3P)2-
PdCl2 (24 mg, 0.034 mmol) were added to the flask. The
mixture was heated at reflux for 72 h under Ar. After
evaporation of THF, the residue was suspended in water and
its pH was adjusted to 10 with dil NaOH, and it was extracted
with AcOEt. The combined organic layers were washed with
brine and dried over Na2SO4. Evaporation of solvent followed
by separation by gel-permeation recycling preparative HPLC
(CHCl3, J AIGEL H1-H2 on LC-908) gave unreacted 8 (34 mg,
38% recovery) and 2-[bis(4-dimethylaminophenyl)methyl]-2′-
dicyanomethylbiphenyl 9 as a colorless solid (36 mg, yield 46%;
yield 73% based on consumption).
To a solution of dihydro derivative 9 (15 mg, 0.032 mmol)
in benzene (1 mL) were added Ag2O (30 mg, 0.13 mmol) and
MgSO4 (30 mg), and the mixture was stirred at room temper-
ature for 40 h. Insoluble material was removed by suction, and
separation by preparative TLC (SiO2, CH2Cl2) gave 2 as a
colorless solid (16 mg, yield 100%).
1
Data of 7: mp 90-90.5 °C; H NMR (400 MHz, CDCl3, 24
°C) δ/ppm 9.77 (1H, d, J ) 1.0 Hz), 8.04 (1H, dd, J ) 7.5, 1.5
Hz), 7.97 (1H, dd, J ) 7.5, 1.5 Hz), 7.67 (1H, ddd, J ) 7.5, 7.5,
1.5 Hz), 7.56 (1H, br dd, J ) 7.5, 7.5 Hz), 7.44 (1H, ddd, J )
7.5, 7.5, 1.5 Hz), 7.32 (1H, dd, J ) 7.5, 1.5 Hz), 7.28 (1H, br d,
J ) 7.5 Hz), 7.13 (1H, ddd, J ) 7.5, 7.5, 1.5 Hz); IR (KBr)
2856, 2760, 1690, 1594, 770, 758, cm-1; EI-MS m/z (relative
intensity) 308 (M+, 100%), 181 (95). Anal. Calcd for C13H9OI:
C, 50.67; H, 2.94. Found: C, 50.77; H, 3.04. Data of 8: mp
129-131 °C; 1H NMR (400 MHz, CDCl3, 24 °C) δ/ppm 7.92
(1H, dd, J ) 7.5, 1.5 Hz), 7.32 (1H, ddd, J ) 7.5, 7.5, 1.5 Hz),
7.25 (1H, ddd, J ) 7.5, 7.5, 1.5 Hz), 7.12 (1H, br d, J ) 7.5
Hz), 7.11 (1H, br dd, J ) 7.5, 7.5 Hz), 7.05 (1H, dd, J ) 7.5,
1.5 Hz), 7.01-6.94 (3H, m), 6.72-6.53 (7H, br m), 5.03 (1H,
s), 2.90 (6H, s), 2.89 (6H, s); IR (KBr) 1614, 1518, 1346, 754
cm-1; EI-MS m/z (relative intensity) 532 (M+, 100%), 405 (86),
284 (50), 253 (44). Anal. Calcd for C29H29N2I: C, 65.41; H, 5.49;
N, 5.26. Found: C, 65.93; H, 5.57 N, 5.23; HRMS calcd
532.1378, observed 532.1377. Data of 9: mp 167-168.5 °C;
1H NMR (400 MHz, CDCl3, 24 °C) δ/ppm 7.62 (1H, m), 7.56-
7.48 (2H, m), 7.37 (1H, ddd, J ) 7.5, 7.5, 1.5 Hz), 7.35 (1H,
(23) Neugebauer, N.; Kos, A. J .; Schleyer, P. v. R. J . Organomet.
Chem. 1982, 228, 107.
(24) Wittig, G.; Herwig, W. Chem. Ber. 1954, 87, 1511.