Mondal et al.
1H NMR (300 MHz, CDCl3) δ 1.7 (s, broad, 3 H), 2.25 (s, 3 H),
2.65 (s, broad, 3 H), 6.75 (s, broad, 1 H), 7.0 (s, 2 H), 7.6 (m, 3
H), 7.8 (m, 1 H), 8.05 (s, 1 H), 8.55 (s, 1 H); 13C NMR (300
MHz, CDCl3) δ 20.9, 79.9, 120.7, 124.7, 126.8, 126.9, 128.2, 129.0,
129.1, 130.0, 133.1, 136.4, 139.0, 143.4, 170.8; mass spectrum
(GC-MS) m/e M+ 302 (35), 281 (10), 257 (10), 243 (20), 228
(20), 207 (50), 147 (100).
Lactols 7a-d. Dry THF (25 mL) was added to a round-bottom
flask containing 6a (7.3 mmol) under argon. The container was
placed in an ice bath (-5-0 °C) and stirred for few minutes. A
solution of the phenylmagnesium bromide in ether (29.1 mmol)
was added dropwise over 20 min. Stirring was continued for another
0.5 h at 0 °C. The reaction mixture was poured onto a saturated
solution of ammonium chloride. The organic layer was extracted
with ether. The resulting solution was dried over sodium sulfate
and evaporated to get an oily product (crude 7a). Crude 7b-d were
synthesized similarly by allowing 6b-d to react with the corre-
sponding Grignard reagents. The Grignard reagents were freshly
prepared following a general procedure. Since bromomesitylene
reacts slowly with magnesium in ethyl ether, a modified procedure
was employed to synthesize the mesityl Grignard reagent.25
Crude 7a was purified by washing with hexanes. Crude 7b-d
were passed through a pad of alumina with dichloromethane.
Evaporating the solvent produced solid white products.
1,3-Dihydro-1,3-diphenylnaphtho[2,3-c]furan-1-ol (7a): yield
) 82%; mp 158-160 °C (lit.10 mp 155-160 °C); mass spectrum
(DIP-MS) m/e M+ 338 (70), 320 (100).
1,3-Dihydro-1-(p-tert-butylphenyl)-3-phenylnaphtho[2,3-c]-
furan-1-ol (7b): yield ) 56%; mass spectrum (DIP-MS) m/e M+
259 (70), 289 (15), 319 (15), 337 (100), 361 (35), 376 (25), 394
(13).
1,3-Dihydro-1,3-bis(p-tert-butylphenyl)naphtho[2,3-c]furan-
1-ol (7c): yield ) 62%; mass spectrum (DIP-MS) m/e M+ 450
(5), 432 (100), 417 (60), 393 (15). 377 (20).
1,3-Dihydro-1,3-dimesitoylnaphtho[2,3-c]furan-1-ol (7d): yield
) 86%; mass spectrum (DIP-MS) m/e M+ 422 (25), 404 (15), 389
(5), 301 (25), 287 (100), 273 (10), 256 (30).
1,3-Diphenylnaphtho[2,3-c]furan (8). A mixture of 7a (2.43
g, 7.1 mmol) and glacial acetic acid (25 mL) was heated on a hot
plate to a moderate temperature (∼60 °C) and stirred with a glass
rod until all of the white lactol was converted to the red furan. The
reaction mixture was then cooled to ∼10 °C in an ice-water bath.
This, upon filtration and washing with petroleum ether, produced
1.66 g of 8 (72%): mp 146-147 °C (lit.10 mp 148-154 °C); mass
spectrum (DIP-MS) m/e M+ 320 (100), 289 (30), 259(40).
6,8,15,17-Tetraaryl-7,16-quinone (10a-c). Compound 10a was
synthesized according to a literature procedure starting from 8.11
Compounds 10b and 10c, however, were prepared by a modified
direct method during which both the Diels-Alder reaction and the
subsequent dehydration steps were carried out in situ.
p-Toluenesulfonic acid (1.52 g, 8 mmol) and p-benzoquinone
(0.108 g, 1 mmol) were added to a suspension of 7b or 7c (2 mmol)
in 35 mL of dry benzene, and the reaction mixture was refluxed
for 15 h on an oil bath. Subsequently, the mixture was allowed to
cool to room temperature and was diluted with benzene. The organic
extract was washed with saturated sodium bicarbonate and brine
solution. Finally, the organic layer was concentrated on a rotary
evaporator and subjected to column chromatography (silica gel).
Elution was begun with 20% (vol.) of dichloromethane in hexane
and finished with 50% (vol.) of dichloromethane in hexane.
Yellowish-brown product was obtained after evaporation of the
solvent.
spectrum (MALDI) m/e M+ 827.42, 826.43, 825.43, 824.41, 823.42;
HRMS (FAB) m/z ) 825.3736 (M + H+), calcd m/z ) 825.373256.
6,8,15,17-Tetrakis-(p-tert-butylphenyl)-7,16-quinone (10c): yield
) 40%; 1H NMR (300 MHz, CDCl3) δ 1.464 (s, 36 H), 7.29 (d, 8
H, J ) 8 Hz), 7.4 (dd, 4 H, J ) 6.4, 6.4 Hz), 7.47 (d, 8 H, J ) 8.4
Hz), 7.8 (dd, 4 H, J ) 6.4, 6.4 Hz), 8.018 (s, 4 H); mass spectrum
(MALDI) m/e M+ 936.77; HRMS (FAB) m/z ) 937.4988 (M +
H+), calcd m/z ) 937.498457.
2,3-Dimesitoylnaphthalene (11). Compound 7d leads to 11
under the same conditions as used for the synthesis of 10b or 10c
1
from 7b or 7c, respectively: yield ) 60%; H NMR (300 MHz,
CDCl3) δ 2.0 (s, 6 H), 2.05 (s, 3 H), 2.22 (s, 3 H), 2.32 (s, 3 H),
2.7 (s, 3 H), 6.85 (s, 2 H), 6.97 (s, 1 H), 7.1 (s, 1 H), 7.5-7.7 (m,
2 H), 7.8-8.0 (m, 4 H); mass spectrum (DIP) m/e M+ 420 (70),
405 (60), 389 (80), 299 (75), 285 (55), 273 (100); HRMS (FAB)
m/z ) 421.2166 (M + H+), calcd m/z ) 421.216755.
7,16-Dihydro-6,8,15,17-tetraphenylheptacene (1). To a suspen-
sion of 10a (0.22 g, 0.3 mmol) in 10 mL of THF cooled to 0 °C
was added dropwise a 1 M solution of borane‚THF (0.9 mL, 0.9
mmol) under an argon atmosphere. The mixture was allowed to
stir for 1 h at room temperature. The temperature was increased
very slowly to 50 °C and the mixture stirred for another 12 h. The
reaction mixture was allowed to cool to room temperature, and an
additional quantity of 1 M BH3‚THF solution in THF (0.9 mL, 0.9
mmol) was added. The temperature was slowly increased again to
50 °C, and stirring was continued for 12 h. After being cooled to
room temperature, the reaction mixture was quenched with metha-
nol. The product concentrated on a rotary evaporator and subjected
to column chromatography (silica gel). Elution was begun with 5%
(vol) of dichloromethane in hexane and finished with 20% (vol) of
dichloromethane in hexane. Evaporation of the solvent produced
pure 1 in the form of a yellowish white solid (0.08 gm, yield
38%): 1H NMR (300 MHz, CDCl3) δ 3.9 (s, 4 H), 7.24-7.32 (m,
18 H, CDCl3), 7.40 (m, 12 H), 7.74 (dd, 4 H, J ) 6, 6 Hz), 7.96
(s, 4 H); 13C NMR (300 MHz, CDCl3) δ 32, 124.97, 125.31, 126.97,
128.19, 128.32, 130.49, 130.75, 131, 133.5, 135.8, 139; mass
spectrum (DIP-MS) m/z M+ 685 (60), 684 (100), 607 (50), 530
(30); mass spectrum (MALDI) m/e M+ 684.51, 685.51, 686.51;
HRMS (FAB) m/z ) 685.2899 (M + H+), calcd m/z ) 685.289526.
7,16-Dihydro-6,15-bis(p-tert-butylphenyl)-8,17-diphenylhep-
tacene (2). Compound 2 was obtained from 10b (yield -30%),
using the same procedure described for the synthesis of 1: 1H NMR
(300 MHz, CDCl3) δ 1.4 (s, 3 H), 1.45 (s, 15 H), 3.9 (s, 3 H), 4.1
(s, 1 H) 7.15 (m, 3 H), 7.3 (m, 8 H), 7.42 (m, 10 H), 7.75 (m, 5
H), 7.95 (s, 2 H), 8 (s, 2 H); 13C NMR (300 MHz, CDCl3) δ 31.8,
33.7, 35, 125, 125.3, 128.2, 130.2, 130.9, 131.1, 134, 135.5., 136,
139.7; mass spectrum (MALDI) m/e M+ 797.68, 796.68; HRMS
(FAB) m/z ) 797.4148 (M + H+), calcd m/z ) 797.414727.
7,16-Dihydro-6,8,15,17-tetrakis(p-tert-butylphenyl)hepta-
cene (3). Compound 3 was obtained from 10c (yield 33%) using
the same procedure described for the synthesis of 1 (instead of 50
°C, the temperature was raised to 60 °C in this case): 1H NMR
(300 MHz, CDCl3) δ 1.45 (s, 36 H), 4.1 (s, 4 H), 7.3 (m, 12 H),
7.45 (d, 8 H, J ) 8 Hz), 7.7 (dd, 4 H, J ) 6, 6 Hz), 7.8 (s, 4 H);
13C NMR (300 MHz, CDCl3) δ 32, 34, 35, 124.6, 125, 125.2, 128.2,
130, 130.5, 131.5, 133.5, 135.8, 136.2; mass spectrum (MALDI),
m/e M+ 908.66; HRMS (FAB) m/z ) 909.5402 (M + H+), calcd
m/z ) 909.539928.
X-ray Crystallography. Data collection was performed at 150
K with Mo KR.26 Intensity data were collected using three different
φ settings and 0.3° increment ω scans, 2θ < 56.58°, which
corresponds to more than a hemisphere of data. The SAINT26
program was used for data integration, and corrections for absorp-
6,15-Bis(p-tert-butylphenyl)-8,17-diphenyl-7,16-quinone (10b):
yield ) 41%; 1H NMR (300 MHz, CDCl3) δ 1.45 (s, 18 H), 7.3-
7.5 (m, 22 H), 7.7-7.9 (m, 4 H), 8.15 (s, 2 H), 8.25 (s, 2 H); mass
(25) Hawkins, R. T.; Lennarz, W. J.; Snyder, H. R. J. Am. Chem. Soc.
1960, 82, 3053.
(26) Bruker SMART (Ver. 5.05) and SAINT-Plus (Ver. 7.08); Bruker AXS
Inc.: Madison, WI, 1999.
4090 J. Org. Chem., Vol. 71, No. 11, 2006